03 alibegovic sarah 28 physical energy

7232019 03 Alibegovic Sarah 28 Physical Energy

httpslidepdfcomreaderfull03-alibegovic-sarah-28-physical-energy 117

Physical energy for drug delivery poration concentrationand activation

Shanmugamurthy L akshmanan ab Gaurav K Gupta ab Pinar Avci ab Rakkiyappan Chandran aMagesh Sadasivam a Ana Elisa Sera1047297m Jorge ad Michael R Hamblin abc

a Wellman Center for Photomedicine Massachusetts General Hospital Boston MA 02114 USAb Department of Dermatology Harvard Medical School Boston MA 02114 USAc Harvard-MIT Division of Health Sciences and Technology Cambridge MA 02119 USAd Programa de Poacutes-Graduaccedilatildeo InterunidadesBioengenharia - EESCFMRPIQSC and Laboratoacuterio de BiofotocircnicaInstituto de Fiacutesica de Satildeo Carlosndash Universidade de Satildeo Paulo Satildeo Carlos SPBrazil

a b s t r a c ta r t i c l e i n f o

Available online 7 June 2013

Keywords

ElectroporationGene transfectionMagnetoporationNanoparticlesOptoporationPhotothermal therapySmart drug carriersSonoporationThermoporation

Techniques for controlling the rate and duration of drug delivery while targeting speci1047297c locations of thebody for treatment to deliver the cargo (drugs or DNA) to particular parts of the body by what are becomingcalled ldquosmart drug carriersrdquo have gained increased attention during recent years Using such smart carriersresearchers have also been investigating a number of physical energy forces including magnetic 1047297elds ultra-sound electric 1047297elds temperature gradients photoactivation or photorelease mechanisms and mechanicalforces to enhance drug delivery within the targeted cells or tissues and also to activate the drugs using a similaror a different type of external trigger This review aims to cover a number of such physical energy modalities Var-ious advanced techniquessuch as magnetoporation electroporation iontophoresis sonoporationmechnoporationphonophoresis optoporation and thermoporation willbe covered in the review Special emphasis willbe placed onphotodynamictherapy owingto theexperience of theauthors laboratory in this area butothertypes of drug cargoand DNA vectors will also be covered Photothermal therapy and theranostics will also be discussed

copy 2013 Elsevier BV All rights reserved

Contents

1 Introduction 992 Photodynamic therapy 1003 Magnetic drug and gene targeting magnetoporation 101

31 Parameters that affect magnetic drug delivery ef 1047297ciency 10332 Limitations and possible solutions 103

4 Electric 1047297eld drug and gene delivery electroporation and iontophoresis 10341 Parameters that affect electric 1047297eld druggene delivery ef 1047297ciency 10342 Limitations and possible solutions 104

5 Iontophoresis 10451 Parameters affecting the ef 1047297ciency of iontophoresis 105

6 Light induced gene and drug delivery optoporation 10561 Limitations of light 106

7 Temperature induced drug and gene delivery thermoporation and photothermal therapy 1068 Photothermal therapy for activation 106

81 Limitations of thermoporation and photothermal therapy 1079 Acoustic-mediated drug delivery sonoporation (Mechanoporation) phonophoresis sonodynamic therapy 107

91 Sonodynamic therapy 10892 Limitations of acoustic mediated drug delivery 109

10 Theranostics 109

Advanced Drug Delivery Reviews 71 (2014) 98ndash114

This review is part of the Anvanced Drug Delivery Reviews theme issue om Editors Choice 2014 Corresponding author at Department of Dermatology Harvard Medical School BAR 414 Wellman Center for Photomedicine Massachusetts General Hospital 40 Blossom

Street Boston MA 02114 USA Tel +1 617 726 6182 fax + 1 617 726 8566E-mail address hamblinhelixmghharvardedu (MR Hamblin)

0169-409X$ ndash see front matter copy 2013 Elsevier BV All rights reserved

httpdxdoiorg101016jaddr201305010

Contents lists available at ScienceDirect

Advanced Drug Delivery Reviews

j o u r n a l h o m e p a g e w w w e l s e v i e r c o m l o c a t e a d d r



11 Conclusions 109Acknowledgments 111References 111

1 Introduction

The purpose of a drug delivery system (DDS) [12] is to devise amethod that enables delivery of a therapeutic agent that may havesub-optimal physicochemical properties in biological tissue thus en-hancing ef 1047297cacy and safety by controlling the rate time and releaseof the agent [3] Targeted DDS (TDDS) includes the administrationof the therapeutic substance the release of the active ingredientsfrom the DDS and the subsequent transport of the active ingredientsacross the biological membranes to the speci1047297c site of action oftenusing what is so called ldquosmart drug carriersrdquo or ldquosmart nanoparticles(NP)rdquo Smart NP can improve drug delivery mechanisms based ontheir particular formulations [45] NP used in such biomedical appli-cations include lipid-based NP (liposomes) [67] polymeric micelles[89] block ionomer complexes [1011] water-soluble synthetic poly-mers (dendrimers) [1213] inorganic [14] and polymeric NP [15]

nanorods [1617] quantum dots [1819] carbon nanotubes [2021]silica-based NP [22] metal and semiconductor NP upconversion NP[2324] self-illuminating NP [2526] and polymerndashdrug conjugates[27] However the main limitations of employing NP for drug deliveryare the following 1) the relatively small amount of drug that can belinked to each NP 2) the possibility of drug deactivation once it ischemically bound to the NP 3) the possibility of immediate uncon-trollable passive release (burst effect) and 4) NP agglomeration pro-ducing quick elimination from bloodstream by macrophages before

reaching the target cells [28] Most of these factors in turn require injec-tion of unnecessarily high concentrations of NP with potential systemic

toxic effects In orderto overcomesomeof these hurdlesphysical energymethods have been explored to enhance not only NP but also drug andgene delivery

The enhancement of effective drug delivery to the target achievedby the addition of physical energy to the traditional TDDS systems hasbeen widely explored in recent years [29ndash36] These techniques havethe potential to be used in different biological and medical applica-tions as an advanced TDDS that can minimize the current limitationsand unwanted effects Biophysical energy such as electric 1047297elds mag-netic 1047297elds ultrasound and mechanical forces light and temperaturegradients can act as enhancers for drug delivery Technique-speci1047297cterms have been associated with each form of physical energy suchas electroporation [3738] for electric current iontophoresis for electricpotential magnetoporation [3940] for magnetic 1047297eld sonoporation

[4142] mechanoporation [43] and phonophoresis [4445] for ultra-sound optoporation [4647] for pulsed light and thermoporation[4849] for temperature respectively (Fig 1) Table 1 summarizes all of the different types of physical energy used in this review for poratingthe cells The advantages and disadvantages of the techniques are ana-lyzed in the table Synergistic combinations of two or more physical en-ergies such as magnetic-electroporation [50] are also of special interestandhave been explored as a potentialsystem foreffectivedrug deliveryThe formation of temporary pores in the cell membrane achieved

Fig 1 Different physicalenergy modules usedfor drug delivery Drugdelivery enhancers suchas electroporation magnetoporation thermoporation sonoporationand optoporationare

illustrated

99S Lakshmanan et al Advanced Drug Delivery Reviews 71 (2014) 98ndash114



through theapplication of various physical energies is thecommon phe-nomenon involved in such systems Once the pores have been formeddrug-carrying NP or smart drug carriers (SDC) [51] can easily penetratethrough these pores in the membrane and enter the cells where thedruggene is further released and activated Thereby some of theabove-mentioned constraints inherently limiting the ef 1047297cacy of NP canbe overcome by use of physical energies

Smart NP along with the application of physical energy comprise anew arena of novel nanotechnology that enables electrical engineersphysicists chemists biologists and pharmaceutical engineers to ex-plore and develop interdisciplinary research For instance physicistsand engineers can come up with new devices by understanding theconcept of ldquoporationrdquo using different modalities Although there areseveral factors that will affect the ef 1047297ciency of drug delivery whileusing such physical energies the key is the possible optimizationtechniques for individual ldquoporationrdquo methods The aim of this reviewis to cover comprehensive up-to-date information about the usage of various such types of physical energy applications called ldquoporationrdquo

Though many different types of physical energy have been usedfor poration and some for concentration activation is the 1047297nal stepthat completes TDDS after the drug has reached its target Photody-

namic therapy (PDT) [5253] is an emerging therapeutic modality Itis a two-component system thatuses light to activate the photosensitizer(PS) drug after delivery by physical enhancement has been applied andreaches itstargetSpecial emphasis willbe given inthereview to applica-tions in the PDT arena (when relevant) partly due to the experienceof the authors laboratory in PDT nevertheless other types of drugsDNA vectors and transfection procedures will also be covered in thisreview In a similar manner photothermal therapy [54] is also alight-mediated activation process and will be covered as well Can-cer therapy will be emphasized due to the prevailing demand inthis area of biomedicine The ef 1047297cacy of each physical energy systemand the limitations and possible optimization techniques will begiven special importance in the review Theranostics [5556] anemerging multifunctional modality will be discussed in context

with the various techniques of biophysical action

2 Photodynamic therapy

PDT involves the use of photosensitizers (PS) in combination withvisible light of the correct wavelength to excite the PS In the presenceof molecular ground (triplet) state oxygen (3O2) the excited state PStransfers energy or electrons to produce reactive oxygen species(ROS) that are able to kill cells PDT has mostly been developed as a

cancer therapy [57] but recently has been proposed as an antimicro-bial therapy

The PS molecule has a stable electronic con1047297guration in the singletstate withthemost energetic electrons in thehighestoccupied molecularorbital(HOMO)[58] Following absorption of a photon of light of the spe-ci1047297c wavelength according to its absorption spectrum (Fig 2 shows a

Jablonski diagramillustrating theprocess) an electron intheHOMO is ex-cited to the lowest unoccupied molecular orbital (LUMO) causing the PSto reach the unstable and short-lived excited singlet state In this stateseveral processes may rapidly occur such as 1047298uorescence and internalconversion to heat but the most critical of these to PDT is the reversalof the spin of the excited electron (known as intersystem crossing) tothe triplet state of the PS This excited triplet state is less energetic thantheexcited singlet statebuthasa considerably longer lifetime as the ex-

cited electron now with a spin parallel to its former paired electron maynotimmediately fall back down (as it would thenhave identicalquantumnumbers to that of its paired electron thus violating the Pauli ExclusionPrinciple) This much longer lifetime (many μ s as compared to a few ns)means that the triplet PS can survive long enough to carry out chemicalreactions which would not have been possible with the excited singletPS Dyes without a signi1047297cant triplet yield may be highly absorbent or1047298uorescent but are not good PS

The photochemical reactions of the triplet state can be dividedinto two different pathways either the Type I mechanism involvingeminus or hydrogen atom transfer from one molecule to another or theType II mechanisms involving energy transfer to molecular oxygenIt should be noted that both these mechanisms can occur at thesame time but the relative proportions may depend on the PS struc-

ture and also on the microenvironment

Table 1

Comparison of different physical energy modules used for drug delivery

Porationattributes

Electroporation Magnetoporation Thermoporation Sonoporation Optoporation

Physicalenergy

Electric 1047297eld Magnetic 1047297eld Temperature Ultrasound Light

Limitations 1 Narrow range of clinically safe electric1047297eld parameter(refer to current standardsfor safety levels)

1 Limited drugcarrying capacity of MNP due to theirbiodistribution2 Narrow range of magnetic 1047297eld [223]

Low Penetration depth(since only appliedtopically so far)

1 Sonoporation deviceshave poor calibration interms of the amount of ultrasound energyemitted [224]

1 Limited time durationbetween optoporationand drug delivery [225]

Disadvantages 1 Irreversible electroporationCell death with high 1047297elds[226227]2 Electro-mechanicalcoupling effect3 Electrodes are incontact with the subjectthat may result inelectrocution

1 Aggregation of MNPcan cause embolization[228]2 Cytotoxicity atincreased concentrationsof MNP [229]

1 Excess heat can inducethermohaemolysis [230]2 Relies on electric 1047297eld toheat up the 1047297lamentstherefore the disadvantagesof electric 1047297eld use applies

1 Shear forces mayinduce rupture of cells [231]2 Temperature increaseas a function of frequencyeventually rupturing cells[232]

1 Excessivein1047298ammation andrisk worsening(postin1047298ammatoryhyperpigmentation)[233]2 Laser usage andultrastructural changesin epidermis

Advantages 1 Inexpensive and simpleto perform2 Drugs overcome thecell membrane barrier1047297eld [234]

1 Non-invasive natureof the magnetic 1047297eld[235]2 Field modulatedexternally without

electrode contactsunlike EP [235]3 Ef 1047297ciency of drugdelivery is high comparedto one without 1047297eld

1 Non-invasive nature of lowheat compared to EP3 Selective irreparable cellulardamage

1 Less invasive comparedto EP [236]2 Instantimpermeabilizationafter ultrasound exposure

[231]

1 Remote operation[237]less cellular damage2 Enhanced optofectionef 1047297ciency compared to

regular gene delivery[238]3 Deep penetration keynanosurgical tool to themicroscopist [239]

100 S Lakshmanan et al Advanced Drug Delivery Reviews 71 (2014) 98ndash114



The type I pathway can involve an electron-transfer reaction fromthe PS to O2 in the triplet state which results in the formation of toxicoxygen species such as O2bull

minus that can further transfer to form ROSsuch as H2O2 and bullOH which are formed by the Fenton reaction inthe presence of divalent metal ions such as Fe2+ [59] (Eqs (7)ndash(9))Another possible mechanism has been proposed that may operatein cases where the triplet state PS is a good eminus donor Here H2O2

(formed from O2bullminus) can undergo a one eminus reduction to formbullOH + minusOH (the redox potential is only +032 V see Table 1)

The two most prevalent damaging ROS (bullOH and 1O2) are able toreact with many biomolecules in cells The exact targets and reactionmechanisms involved depend on the following considerations Firstlythe localization of the PS generation is critical because most of theROS are highly reactive and cannot travel far from their site of produc-tion before disappearing (these distances are the order of nm to μ m)

Secondly the relative abundance of the target biomolecule is importantThirdly we have the question of whether Type 1 or Type 2 mechanismsproduce the ROS in question

PS are usually organic delocalized aromatic molecules consistingof a central chromophore with auxiliary branches (auxochromes)that are responsible for further electron delocalization of the PSthus altering the absorptionspectra of the PS Due to extensive electrondelocalization PS tendto be deeply colored This means that the energyrequired to excite the eminus in the HOMO to the LUMO is low comparedwith less delocalized molecules and therefore the absorption bandsare in the longer wavelength (red) spectral region and are largere1047298ecting the high probability of excitation

3 Magnetic drug and gene targeting magnetoporation

Magnetic 1047297elds have promising applications in drug delivery dueto their relatively non-invasive nature compared to their counterpartof electrical 1047297elds Magnetic energy is an important technique for de-livering drugs to speci1047297c locationswithin the body [60] this phenom-enon of application of magnetic1047297eld for drug delivery has been calledmagnetic drug targeting (MDT) [6162] In principle MDT consists of the following steps (Fig 3) [63] 1) coupling the drug to the magneticNP (MNP) 2) applying an external magnetic 1047297eld to attract the MNPto the desired location such as a tumor and 3) the release of the drugsfrom the NP under the in1047298uence of external alternating magnetic 1047297eldonce it reaches the target Furthermore applied magnetic 1047297elds canalso be used to release drugs from nanocarriers such as liposomes or

nanoemulsions These nanoparticles can contain superparamagnetic

iron oxide nanoparticles (SPION) that heat up to temperatures of theorder of 45 degC under the in1047298uence of alternating magnetic 1047297elds [64]

MNP have been tested pre-clinically or clinically as targeted drugand gene delivery agents and also to enhance diagnostic imagingsuch as magnetic resonance imaging (MRI) [4] The primary attractivefeatures of MNP for drug delivery include their simplicity of synthesisability to be controlled remotely via magnetic 1047297elds the fact thatmagnetic 1047297elds easily penetrate through biological tissue and theirbiocompatibility and low toxicity [65] One of the unique propertiesof MNP exclusively available on the nanoscale level is the switchablemagnetic properties of superparamagnetic NP which may pave theway for applications in the biomedical 1047297eld which include advancedmedical imaging and cell tracking The primary step in MDT is thattherapeutic agents are attached to or encapsulated within these MNPwhich are exclusively used as magnetic delivery vehicles These MNP

canbe constructed from magnetic cores with a polymer or metal coatingthat can be functionalized (Fig 4) The polymer (that can be modi1047297ed)acts as themost importantmaterialfor modi1047297cationof MNP for drug de-livery Sometimesthe units mayconsist of porouspolymers that containMNP precipitated within the pores Through functionalization of the

Fig 2 Jablonski diagram In the presence of molecular ground (triplet) state oxygen (3O2) the excited state PS transfers energy or electrons to produce reactive oxygen species (ROS)

Fig 3 Schematic representation of a magnetic nanoparticle-based drug delivery systemSteps for magnetic nanoparticle-based drug delivery are coupling the drugto the magneticNP (MNP) applying an external magnetic 1047297eld to attract the MNP to the desired locationsuch as a tumor and the release of the drugs from the NP under the in1047298uence of external

alternating magnetic 1047297eld once it reaches the target




polymer or metal coating it is possible to attach for example cytotoxicdrugs for chemotherapy or DNA for gene delivery [66] Different kindsof functionalization have been described in detail by Chomoucka et al[67] Once functionalized the MNPtherapeutic agent complexes areinjected into the bloodstream often using a catheter to position the in-

jection sitenearto the target Whensolid (rare-earth) externalmagnetstypically with high-1047297eld and high-gradient are focused over the targetsite the magnetic 1047297elds drive the MNP to be accumulated at the targetsite This technique is advantageous over simple direct injection of thedrug into the diseased area as the natural route of drug absorption intothe tissue is via the capillaries rather than a direct bolus of drug intothetissuethat may not be distributed into all thecellsThus trajectoriesof such MNP are almost fully controlled by the externally applied mag-netic 1047297eld though other smaller forces may also coexist While thismay be effective for targets close to the body surface due to the factthat the magnetic 1047297eld strength attenuates rapidly as a function of distance deeper areas within the body become more dif 1047297cult to betargeted [66] Sometimes complicated trajectories are possible in the

presence of an applied 1047297eld drugs attached to MNP can be sloweddown by drag or even captured by other cells that are non-targeted Thedrag force experienced by the MNP is mostly due to theblood 1047298ow insidethe blood vessels In order to effectively overcome the drag themagneticforce due to the external 1047297eld must be greater than the drag force [68]

F frac14 6πηrhv

where η is the viscosity of blood rh is the hydrodynamic radius of theparticle and v is the velocity of the particles It is important to notethat the hydrodynamic radius of the particles could be much largerthan the magnetic radius of the particles this is especially the caseif the particles are coated with polymers and proteins (typical values

rm = 5 nm rh gt 20 nm) [4]In generalthe force experiencedby thematerial(cellsphysicalbody)

when placed in an external magnetic 1047297eld is given by [68]

Fm frac14 μ 0VMnablaH

where V is thevolume of thematerial μ 0 = 4π middot 10minus7 NA2 is the mag-netic permeability of vacuum M is the magnetization (magnetic dipolemoment per unit volume) and H is the applied (auxiliary) magnetic1047297eld The magnetization of the cellsNP canbe taken approximately pro-portional to the applied magnetic 1047297eld up to a certain value called thesaturation magnetization Msat Beyond this level all the constituent di-poles are aligned with the1047297eld and no further increase in magnetizationis possible It is critical that these conditions have to be clearly taken into

account during drug delivery be it the external magnetic 1047297eld or the

particlethat carriesthe magnetic1047297eldeffective deliverymaybe success-fully accomplished onlywhena comprehensive understanding of thebe-havior of 1047297elds is considered

Recently multi wall carbon nanotubes (MWCNT) have been usedas magnetically driven nanotools for effective cell transfection withoutnoticeable cell damage [69] The paramagnetic MWCNT interact withcells when exposed to magnetic 1047297elds driving cell migration towardthe magnetic source Decreased viability of the tumor cells caused by

cell membrane damage accompanied by cell component leakage pavesway for the possibility of an image-guided in situ ablation of tumorsAn increased uptake of cytotoxic agents and magneto-cell lysis produc-ing mechanical tumor ablation is speculated For instance the effect of TiO2 and Fe-doped TiO2 MNP on the activity of HL60 leukemic cellswas studied by observing the in1047298uence on the activity of cells exposedto light compared to un-exposure [70] It was observed that the PS(TiO2) completely eliminated tumor cells using illumination under anapplied magnetic 1047297eld

When using magnetic 1047297elds for gene transfection the phenomenonis called magnetofection For magnetofection to take place in vitro ahigh-1047297eld high-gradient magnetic force is focused onto a multi-wellculture plate in which the cells are growing [66] Next the geneDNAis attached to magnetic NP and the external magnetic 1047297eld is turnedon the external 1047297eld apart from controlling trajectory of the MNP alsoenhances sedimentationratesparticle internalization and geneexpres-sion Although the mechanism of increased internalization is notcompletely understood it is hypothesized that the oscillating 1047297elds in-troduce extra energyto thesystem which produces a non-linearmotionof the particles as they move along the 1047297eld gradient that may aid cellandtissue penetrationFor in vitro controlled transfection three impor-tant points of magnetofection need to be considered they are 1) verylow vector dose 2) reduced incubation time for achieving highmagnetofectiontransduction ef 1047297ciency and 3) the possibility of genedelivery to otherwise non-permissive cells (cells that do not easilyinternalizeDNA material) It is presently uncertainif this magnetofectiontechnique could be usefully applied in vivo

Non-viral gene vectors are considered safer than viruses but owingto their inherent low ef 1047297ciencies limitations apply to their utility in

gene therapy Therefore gene vectors with superparamagnetic NP inconjunction with TDDS using magnetic 1047297elds have been explored [71]The use of super paramagnetic iron oxide nanoparticles (SPION)underoscillatingmagnetic1047297elds(OMF)hasbeenshowntoimprovedif-fusive transport of drugs across biological barriers by increasing thelocal temperatureby inductive heating [72] SPIONoften tend to remainin circulation unaffected by the liver or the immune system The twofunctionalities associatedwith SPION fordrugdeliveryare 1) increaseddelivery into cells and tissues due to heating and motion induced in theSPION by the oscillating 1047297eld that affects the potential for MNP to beused as targeted drug delivery agents under low magnetic 1047297eldstrengths and 2) activation for achieving triggered release of drug at-tached to the surfaces of the particles using OMF with minimal damagecaused due to heating of the surrounding tissues In essence such bio-

compatible magnetic 1047297eld conditions avoid signi1047297cant disruption thatcan be caused by the use of synthetic biopolymers-based NP for drugor gene delivery [65] Combined thermosensitive and magnetic NPhave been utilized in controlled TDDS with added advantages [73] Insuperparamagnetism thermal 1047298uctuations take place such that theycanspontaneously demagnetize a NP that had previouslybeen magnet-ically saturated leaving these particles with no hysteresis [67]

Multi-functional SPION consisting of tetra-ethyl-ortho-silicate(TEOS) encapsulating monodisperse Fe3O4 NP (which serve as a core)and further grafted by poly (N-isopropylacrylamide) (PNIPAM) are of special signi1047297cance These SPION could be introduced to the desiredlocation by external magnetic 1047297eld by controlling the magnetite core[73] There is tremendous potential to further explore MNP as facilita-tors of drug delivery provided that all factors that affect its ef 1047297ciency

are controlled

Fig 4 A typical magnetic nanoparticle Magnetic nanoparticle consists of a magneticcore a protective coating an organic linker and an active molecule




31 Parameters that affect magnetic drug delivery ef 1047297ciency

In MDT the magnetic 1047297eld can be modulated externally in order tocontrol the drug-release with the characteristics of driven magneticaccuracy targeting and high drug-carrying capacity cells This propertyof MDT can be used to lower toxic effectsand to enhance thetherapeuticeffectThe ef 1047297ciency of theMDT fortargeteddrug deliverydepends on atleasta dozen of different factors [4] that includes 1) thesize of the MNP

2) magnetic property of the MNP 3) the biocompatibility of MNP4) physicochemicalproperties of the drug-loadedin theMNP 5) appliedmagnetic 1047297eld strength and geometry of the system 6) penetrationdepthof the targettissue 7) resistivitycaused by blood1047298ow 8) vascularsupply 9) NP aggregation due to large surfacevolume ratio 10) theshort half-life of the particles in blood circulation 11) the low ef 1047297ciencyof theintracellular uptake of NP and 12) nonspeci1047297c targeting Althoughsmall MNP have much better drug delivery properties than larger onesdue to their ability to pass through biological barriers their small sizemay make them insuf 1047297ciently responsive to the applied magnetic 1047297eld

32 Limitations and possible solutions

There are several limitations that hinder full clinical therapeuticusage of MDT The limitations include inappropriate gradient modu-lations by applied magnetic1047297elds which causes non-speci1047297c targeting[4] the potential for embolization (blocking blood 1047298ow) when theparticles accumulate within the bloodstream and the developmentof cytotoxicity as an unwelcome side-effect with the increased con-centration of MNP in the liver However some of these problemsmay be potentially turned to advantage and could increase targetingfor example in the case of tumors in the liver the blood supply to thetumor mass gets blocked [63] Some of the other problems of ef 1047297cientdrug delivery can be avoided if SPION are used as MNP as describedearlier however further investigations need to be carried out for acomprehensive understanding of the 1047297eld

4 Electric 1047297eld drug and gene delivery electroporation and

iontophoresis

Depending on the size and the shape of the cell when a pulse of intense external electric 1047297eld is applied polarization [7475] takesplace the anode facing side becomes hyperpolarized and the cathodefacing side becomes depolarized [76] This leads to a phenomenoncalled ldquocell porationrdquo or ldquocell fusionrdquo that involves the fundamentalbehavior of cell membranes de1047297ned by the term ldquoelectroporationrdquo(EP) EP can introduce dipolar molecules into the cell by varyingmembrane permeability of the cell or tissue [75] EP is inexpensiveand simple to perform in the laboratory and therefore has been widelyused in biomedical research Since traditional methods of increasingcell uptake can involve biological and chemical side effects due to overdosage EP can be used as an enhancer for TTDS with higher spatial res-olution Though the fundamental principle by which the electric1047297eldin-

duces cell poration or cell fusion is not yet thoroughly understood it iswidely assumed that electrical breakdown of the cell membrane couldbe a key explanation of the phenomenon Assuming a spherical cell thecell membrane potential is given by

V max frac14 3=2eth THORN rE cosθ

where θ is the angle between the electric 1047297eld and the normal vector of the cell membrane r is the radius of the cell when placed in an externalelectric 1047297eld of strength E V max is the potential maximum near the cellpoles where θ = 0deg and 180deg For very large E V max reaches a criticalvalue V (on the order of 1 V) the 1047297eld within the cell membrane ishigh enough to cause an electrical breakdown of the lipid bilayer [77]Membrane pores could be created as a result of such breakdown [76]

as shown in Fig 5 Apart from the primary electrical breakdown of the

membrane a second breakdown mechanism of the cell membrane ispossible caused by a phenomena called ldquoelectro-mechanical couplingeffectrdquo [78]

EP has a wide range of applications including drug delivery[79ndash83] and gene transfection (electrofection) [84ndash87] EP has beenincorporated for drug and gene delivery in various areas of the humanbody that include the lung [88ndash90] skin [91ndash93] cornea [9495] spinalcord [9697] heart [9899] brain [100ndash102] and dental tissues [103

104] Owing to its high gene transfection ef 1047297

ciency safety low toxicityand reproducibility EP also has the potential for introducing genes intomammalian cells [105] DNA (pSV2-CAT gene) when introduced into amammalian cell in the presence of electric1047297eld in vivo the transfectionef 1047297ciency was found to multiply by 100ndash1000 times compared to theone without 1047297eld [106]

Similarly experiments have demonstrated that when EP was in-troduced in PDT malignant cells were eradicated in a much shortertime compared to PDT without 1047297eld To demonstrate such capabilitiesof EP in a study a Chinese hamster 1047297broblast cell line (DC-3F) wastargeted using two different PS chlorin(e6) (Ce6) and aluminumphthalocyanine tetrasulfonate (ALPeS4)] with different dose levelsfollowed by EP with 8 electric pulses at 1200 Vcm intensity 01 msduration and 1 Hz frequency After 20 min of incubation the cellswere irradiated using a visible light source (660 nm) The malignantcells were found to be dead in a signi1047297cantly shorter time span provingenhanced ef 1047297cacy contributed by EP [107] Another group applied EP onhuman histiocytic lymphoma U937 and Saccharomyces cerevisiae cellsincorporating some of the reliable PDT agents such as thiopyronineprotoporphyrin zinc phthalocyanine copper phthalocyanine sulfonateadriamycin and daunomysin and achieved remarkable results fromtheir experiments The dye diffused rapidly into the porated cells andthe membranes resealed over a period of 6ndash10 min Faster destructionof all resealed cells compared to control cells (without EP treatment)has been observed in these experiments demonstrating the advantagesof the applied electric 1047297eld

Field strength is an important parameter in EP that needs to be con-trolled for better ef 1047297cacy of druggene delivery Recently high-intensitydirect current (DC) electric 1047297eld has been applied for electroporation in

cancer therapy In an experiment macromolecular chromophore dex-trans (cibacronndashdextran) acting as PS were transported into cancercells (U-937 cells) by electroporation of their membrane using shortpulses in between two electrodes dipped in culture medium After elec-troporation by electric pulses the penetration of cibacron blue dextranand the resealing of membrane pores during 20 min in the dark tookplace andthe followingirradiation by 66 Jcm2 light produced a distinctPDT effecton cancer cells [108] However in thecontrol measurementsPDT alone using cibacronndashdextran produced negligible effect LikewiseXu et al [109] observed that a combination of EP and TiO2-conjugatedNP with monoclonal antibody showed signi1047297cant photokilling afterphotoexcitation While EP accelerated the delivery speed of the TiO2

NP to cancer cells the use of monoclonal antibody increased thephotokilling selectivity of TiO2 NP to cancer cells with less damage to

healthy cellsThere are several ongoing clinical trials that are associated with

EP-mediated gene delivery [110] However ef 1047297cient use of EP fordruggene delivery is still in a preliminary stage due to possible side-effects of electric 1047297elds and currents and further research is underway

41 Parameters that affect electric 1047297eld druggene delivery ef 1047297ciency

Genedrug delivery ef 1047297cacy during EP relies on cell membranepermeability and electrophoresis [111] The formation of pores suchthat membrane reseals when 1047297eld is turned off is a prerequisite fordruggene entry The size of pores and number of pores created areimportant parameters to be considered for druggene delivery ef 1047297cacyThe pore size is directly proportional to the applied electrophoretic

force The pore size is also affected by the presence of anionic lipids




during EP [112] Peng et al investigatedthe number of pores created and

the dependence on the interaction of the DNA plasmid fragments withthe electroporated membranes [110] It was found that a relatively lownumber of electropores were necessary to avoid toxicity and that poly-meric forms of the DNA vectors enhanced the transgene expression togive ef 1047297cient delivery Electrofection ef 1047297ciency depends on a numberof optimizing parameters including 1) electric pulse parameters2) electrode design 3) DNA buffer composition and 4) pretreatmentsof the target tissue The overall goal is to produce the optimum numberof temporary pores to allow DNA penetration into the cell withoutallowingthe pores to remain openlong enough to adversely affectcriticalcellular physiology leading to cell death


Strongelectrical1047297elds can produce permanent cell permeabilizationand thereby consequent lossof cell homeostasis eventually leads to celldeath a process knownas irreversibleEP [113] Intense electric1047297eldim-pulses produce a mechanical shock (similar to forced oscillation usingultrasound) disrupting the structure of the membrane locally For thethicknessof themembrane(6 times 10minus7 cm)when themembranepoten-tial is on the order of 1 V the electric 1047297eld within the cell membranewill exceed 10(6) Vcm and the following two processes can takeplace [113] 1) compression of the lipid bilayer normal to the surfaceleading to electrical breakdown of the membrane and 2) the chargedgroups of the membrane are forced to move in the direction of the1047297eld leading to mechanical stress in the membrane eventuallydisrupting it In order to avoid breakdown it would be more effectiveto apply an oscillating electric 1047297eld to induce poration than to apply a

DC 1047297eld EP has been widely applied for gene delivery in experimental

animals to improve cancer treatment vaccination and wound healing

[114ndash116] and has been tested in a clinical trial of interleukin-12 plas-mid delivery for melanoma [117]

5 Iontophoresis

Iontophoresis which also uses an electric 1047297eld is an emerging mo-dality of drug delivery through the skin by using a potential produc-ing only a gentle electrical current [118119] Unlike the formationof pores in EP in iontophoresis the ionized form of the drug pene-trates through sweat ducts sebaceous glands hair follicles and im-perfection sites in the skin layer The iontophoresis unit carries ananode drug reservoir that holds and releases the drug and a cathodethat collects the opposite ions when a potential is applied across the

two polarities as shown in Fig 6 [120121] When a potential differenceis applied the cationic molecules that are placed under the cathode arerepelled due to the same charge and are transported through the der-mal layers into deeper structures underlying the skin and absorbedinto the bloodstream Similarly anions originating from tissues belowthe surface of the skin are extracted into the counter electrode whichis the ldquoanoderdquo Iontophoresis has been proposed for numerous usesincluding the delivery of local anesthetics before skin procedures inchildren thus avoiding injections local drug delivery for agents suchas non-steroidal anti-in1047298ammatory drugs (NSAID) or corticosteroidsfor musculoskeletal in1047298ammatory disorders [122] Singh et al [123]investigated modulated iontophoresis that involves microneedles intransdermal permeation of ropinirole hydrochloride in Parkinsonsdisease therapy and succeeded in delivering therapeutic amounts over

a suitable patch area and time

Fig 5 Electroporation phenomenon Electric 1047297eld disrupts cell membrane allowing druggene poration The status of druggenes before pulse during the electric 1047297eld (E-1047297eld) andafter pulse is shown




In PDTfor skin cancer(actinickeratosis(AK)) [124] whentraditionalmethod is used thePS 5-aminolevulinic acid (ALA) is absorbed percuta-neously through passive diffusion which requires 4ndash6 h waiting timebefore performing theprocedure In order to1047297nd an alternative method

to accelerate the PS delivery ALA was iontophoresed using direct-current pulsed iontophoresis Protoporphyrin IX (PpIX) production fol-lowing iontophoresis was comparable to the conventional occlusivedressing technique (ODT) and biopsies from the treated lesion demon-strated disappearance of AK

51 Parameters affecting the ef 1047297ciency of iontophoresis

Several parameters affect the transdermal absorption of drugsthrough iontophoresis including 1) concentration of drug 2) polarityand ionizable property of drugs 3) pH of donor solution 4) co-ionsavailability 5) ionic strength of solution and 6) electrode polarity

6 Light induced gene and drug delivery optoporation

Owing to the ready availability of light sources and the good bio-compatibility of light in biological systems light has been evaluatedfor its use as an effective drug delivery enhancer When light is usedas an enhancer in druggene delivery then the phenomenon is calledas ldquooptoporationrdquo From fundamental experimental research to clini-cal practice successfuloptoporationtechniqueshave beeninvestigatedSince light spans a wide electromagnetic spectrum (Fig 7) and the factthat some of the wavelengths can penetrate deep into the bodyoptoporation takes advantage of this special property Optoporationhas the potential to facilitate the permeation of topically applied drugsinto deep tissue layers mainly by means of light or lasers (light ampli-1047297cationby stimulated emission of radiation) Particularly in theskinab-lative fractional resurfacing procedures using CO2 (10600 nm) and

erbium-doped yttriumndash

aluminumndash

garnet (ErYAG mdash

2940 nm) lasers

have gainedpopularitydue to their capabilityto disrupt themajor cuta-neous barrier ndash the stratum corneumndash by creating vertical micro chan-nels (Fig 8) which serve as pathways for the deep penetration of druginto skin layers [63]

The ablative fractional laser technique (Fraxel) was found to be aneffective clinical procedure to enhance targeted drug delivery Usingthis technique Togsverd-Bo et al [125] conducted a randomized clin-ical trial comparing the fractional laser-assisted PDT with ordinaryPDT for actinic keratosis (AK) in a 1047297eld-cancerized face and scalpusing CO2 Fraxel laser on 1047297fteen patients Patients had two symmetri-cal sides treated one with ablative fractional laser prior to the PDTand the other with PDT only When the drug methyl aminolevulinate(MAL) a precursor of PpIX was topically occluded followed by PDT illu-mination with red light a better therapeutic effect on the Fraxel-treatedsite compared with thenon-treatedsite wasobserved Duringsuchabla-tive techniquesit is necessary to understand that thedepthof drug entryinto theskin depends on theenergyof thelight transmitted andalso thepulse duration In order to understand depth as a function of the energy

of the light a study was conducted on ablative fraction laser technique[126] In this study MAL was applied on Yorkshire swine normal skintreated with CO2 laser with pulse durationsof 3 ms anddelivering ener-gies of 37 190 and 380 mJ per laser channel This procedure createdthree different hole-depths which reached down to 2100 μ m intodeepdermissubcutaneous layer It was found that different intradermallaser channel depths enhance the drug permeation throughout the skinlayers but it did not affect the PpIX accumulation

CO2 fractional lasers are now popularly used for such studiesowing to their inherent capabilities In order to achieve similar resultsrecently YAG laser was also suggested as an alternative method For in-stance using the ErYAG (2940 nm) laser in an experimental ex vivostudy Forsteret al [127] observed the penetrationenhancementof top-ical 5-aminolevulinic acid (ALA) 20 mdash a precursor PpIX on a porcine

skin model It was observed that the PpIX 1047298uorescence was observed

Fig 6 Iontophoresis method The iontophoresis unit carries an anode drug reservoir that holds and releases the drug and a cathode that collects the opposite ions when a potentialis applied across the two polarities




in deeper skin layers compared with non-ablated skin Lee et al com-pared the ability of ErYAG and CO2 lasers and microdermabrasion interms of enhancement andcontrol of in vitro skin permeation anddepo-sitionof vitamin C [128]The1047298ux andskin deposition of vitamin C acrossmicrodermabrasion-treated skin was found to be almost 20-fold higherthan that across intact skin Among the modalities tested ErYAG laserdemonstrated the greatest enhancement of skin permeation of vitaminC It was further emphasized that the laser 1047298uence and spot size playedimportant roles in controlling drug absorption

There are also other kinds of lasers used for optoporation Using anargon ion laser (488 nm) and phenol red as a light absorbing dye theplasma membrane of Chinese hamster ovary cells was madepermeablewhen the beam was focused [129] With irradiation with laser genetransfection has also been studied Optical transfection is sometimescalled ldquooptofectionrdquo Optofection effects were studied using a green1047298uorescent protein (GFP) encoding plasmid [129] The optofectionrates after laser irradiation were around 30 for younger cells and less

than 10 for aged cells

61 Limitations of light

Although optoporation has shown promising results some reportsraise concerns about being used with PDT owing to the phototoxiceffects of PDT such as in1047298ammatory response and exacerbation of pain [130ndash132] attributed to the use of high PS concentration andhigh light 1047298uences [133ndash135] Another remarkable side effect isprolonged skin pigmentation A recent study on ex vivo full-thicknessporcine skin model has reported damage to the epidermis by thermaleffects and other toxic outcomes at higher 1047298uence rates which canlead to ultrastructural changes in epidermis [136] However these

drawbacks can be avoided by decreasing the amount of light energydelivered to the tissue There have been a few clinical studies withvery small sample size conducted in order to understand such effectsHowever controlled clinical studies that include histopathological out-comes need to be conducted in order to establish safe and effectiveparameters required for this therapy

Nanobiophotonics is also an emerging1047297eld that uses light for molecu-lar diagnostics that involves speci1047297c sequence characterization of nucleicacids for gene delivery systems of relevance for therapeutic strategies[137] Though light can enhance the drug delivery into deeper layers of the tissue by opening microchannels that allows the molecule uptakefurther randomized clinical trials are required to ensure standards inoptoporation ef 1047297cacy

7 Temperature induced drug and gene delivery thermoporation

and photothermal therapy

Thermoporation (TP) also alternatively called lsquomicroporationrsquo makesuseof heat to produce tiny openings in thestratum corneum [138] Heatis generated by an array of metallic 1047297laments held temporarily againstthe skin An activation electric pulse induces heating of the 1047297lamentsA vaccine or drug is applied over the created pores via an adhesivepatch for treatment In a study Ivanov et al studied the structuralchanges in erythrocyte membrane during thermoporation involved inthermohaemolysis [138] When intense electric 1047297elds (15 kV cmminus1

for 5 s) were applied on cell suspension medium heat variations wereobserved However corresponding classical thermal treatments atequivalent temperatures had no effect on the viability of cells [139] Itis commonly assumed that electrical conductivity variations of theintra-andextra-cellularmatrix causedby ions andsolute transfer acrossthe membrane were shown to be involved in the observed heating

Though thermoporation is a less common technique that is used forporation andconcentration of drug or gene the most popular techniquethat combines both heat and light for activation is called ldquophotothermaltherapyrdquo is rapidly growing recently

8 Photothermal therapy for activation

Photothermal therapy (PTT) is a model with some similarities toPDT Unlike PDT where the excited PS releases singlet oxygen or freeradicals PTT takes advantage of the excited PS releasing vibrationalenergy in the form of heat PTT uses near infrared radiation (NIR) andmany different NPas agentsto inducekillingof theunwanted cellsor tis-sues When lasers are used as the activation source several factors needto be considered for ef 1047297cacy 1) tissueabsorption coef 1047297cient 2) thermal

relaxation time 3) thesensitization of thetissue 4) time duration of the

Fig 7 Light penetration as a function of wavelength There exists a lsquowindow of transparencyrsquo for human tissues in the far-red spectrum light is still limited in its penetration depthor how far it can penetrate into the human body

Fig 8 Optoporation Schematic representation of micro-channels created by ablativefractional lasers in skin The light beam disrupts the major skin barrier the stratum

corneum (SC) and reaches deeper layers (dermis)




laser exposure and 5) tissue thickness [140] Photothermal sensitizerssuchas metallo derivatives of porphyrins and porphyrinoid compoundsazo dyes and triphenylmethane derivatives are used in this case for PTT[140] Photothermaldamage of tissues may be induced by pulsedirradi-ation of either endogenous chromophores added or dyes Dyes have theadvantageof signi1047297cant absorbance at wavelengths longerthan 600 nmthat can penetrate deep into biological tissues Spatial con1047297nement of the photothermal process depends on the absorption coef 1047297cient of the

photoexcited chromophore and its thermal relaxation time In additionthe use of lasers in PTT has shown promising results for cancer therapysince the start of thedecade Inthestudy conducted byChenetal murinemammary tumors were treated using 808 nm laser with indocyanine asthe PTT agent [141] Tumor regression was clearly observed when thetreatment involved 3ndash5 min timedurationwith5ndash10 W power howeverthe ef 1047297cacy of the PTT against cancer was of concern In a clinical studyfeasibility and safety of image guided targeted photothermal therapy forlocalizedprostatecancer were testedPTTwasemployed to lowrisk pros-trate patients using optical 1047297bers and treated with minimal adverseeffects Successful results from such in vitro and in vivo studies for cancerapplication through various agents have helped in moving forward withfurther exploration towards translational studies [142] PTT has provedeffective against breast tumors [143] Lewis lung carcinoma in mice[144] localized prostate cancer [142] murine glioma model [145] andEhrlich carcinoma tumors [146] and gene therapy For instance Au NPcovalently linked to a viral vector was used in gene cancer therapy[147] When gene transfection takes place using thermal vibrations thephenomenon is known as ldquothermofectionrdquo PTT killing can be broadlyclassi1047297ed according to photosensitizer-induced [148] and hyperthermia-induced [149] based on the type of molecule is encapsulated by the NP

Advancements in synthesis of NP provide a wide choice of materialsfor encapsulating PTT drugs which include but not limited to goldnanoshell gold nanocages gold nano particles carbon nanotubesgraphene copper sul1047297de (CuS) and Single Wall Carbon Nanotube(SWCNT) The unique optical properties of such NP make them strongoptical absorbers suitable for PTT [150] The NIR spectral range of 750ndash1300 nm falls in the optical therapeutic window which allowsmaximum penetration depth into the biological tissue Among the NP

gold nanorods are widely preferred for PTT due to their antenna-likestructurethat hastwo absorption bands due to thesurface plasmonres-onance oscillation These physical properties improve the absorption of the light used to excite the nanorods Gold- and CNT-conjugates showhigh selectivity towards cancer cells with destructive effects of laser ir-radiation One of the upcoming gold nanostructures is the hollow goldnano cages for anticancer applications They are usually of 30ndash50 nmin size and highly tunable to the NIR region Likewise polyethylene gly-col (PEGylated) nanogels (Fig 9) containing gold nanoparticles are of great interest [151]

Another carbon nanomaterial known for NIR absorption is singlewall carbon nanotubes SWCNT with low cytotoxicity For instanceCobalt Molybdenum Catalyst (CoMoCAT) SWCNT [152] with a narrowabsorption peak at 980 nm was conjugated with folate receptor for

tumor targeting Laser irradiation (1047298uence 300 Jcm2

) was directedonto the tumor site 8 days after the injection of folate-SWCNT directlyinto the center of the tumor (EMT6 cells) in a Balbc female mouseThe experiment was reported to produce signi1047297cant tumor destruction

Thoughboth in vivo andin vitro experimental trialsshow promisingpotentialfor PTT furtherresearchis necessaryto improve theef 1047297cacyof PTT

81 Limitations of thermoporation and photothermal therapy

Excess heat can produce burns (thermal or photothermal damage)on normal cells [153] Only applied topically and deeper penetrationinto tissue is a challenge with this technique Since the heat 1047297lamentsare connected electrically some of the limitations of using electric

1047297eld also apply here

9 Acoustic-mediated drug delivery sonoporation (Mechanoporation)

phonophoresis sonodynamic therapy

Acoustic targeted drug delivery (ATDD) has been explored as apromising method to enhance the delivery of therapeutic agents tothe target tissues The underlying mechanism for ATDD is the use of ultrasound energy mediated transport of molecules into the targettissues Ultrasound is de1047297ned as the transmission of sound pressure

waves with a frequency greater than 20000 Hz the upper limit of human hearing The technique of using ultrasound for druggenedelivery is called ldquosonoporationrdquo Ultrasound waves can be refractedor re1047298ected similar to light waves However in ultrasound wavesthe actual movement of molecules with compression or expansionof medium takes place Thus ultrasound waves being very physicalin nature they can dynamically interact with biomolecules or cellsAnother unique property of ultrasound waves is that there is relative-ly little absorption of these waves by body 1047298uids and tissues There-fore ultrasound can be used for non-invasive painless transmissionof energy at speci1047297c body locations which is the foundation forATDD Thus ultrasound enhances drug delivery by various mecha-nisms including induction of tissue hyperthermia [154155] and therecently discovered remarkable ability of these waves to produce cavi-tation activity [156ndash159] The exposure of a medium to ultrasoundcauses the formation andor activity of gas-1047297lled microbubbles calledcavitation bubbles [160] The use of ultrasound as an enhancer is re-ferred to as phonophoresis or sonophoresis [44161] ldquoSonoporationrdquo

can be de1047297ned as a ldquophysicalrdquo method in which an ultrasound is ap-plied in the presence of microbubbles that act as cavitation nuclei toporate the plasma membrane in order to allow direct transfer of mole-cules into the cytoplasm [162] of the cell Sonoporation involves ultra-sound contrast agents (UCA) [42] to permit the transfer of drug andgenes into cells However it is a transient and reversible phenomenonthat ensures relativelygood cell viability A major challengeto theappli-cation of sonoporation in case of gene delivery is to optimize the ultra-sound parameters both to obtainhigh gene transfectionandto maintaingood cell viability [163] Another requirement is to avoid prematurerelease of the cargo after ultrasound activation (dose-dumping) to pro-

duce predictable controlled release kineticsCavitation bubbles expand and shrink in response to low- and

high-pressure portion of the ultrasound wave If the resultant oscilla-tion in the bubble size is stable (repeatable over many cycles) it iscalled lsquostablersquo or lsquonon-inertialrsquo cavitation A circulating 1047298uid 1047298ow(microstreaming) [164165] is created by such oscillations aroundthe bubble with velocities and shear rates proportional to the oscilla-tion amplitude The associated shearing forces generated at high am-plitudes have the capacity to shear open synthetic vesicles such asliposomes [164] Therefore ultrasound-mediated delivery of drugsand genes is a complex mechanism with interplay among target tissuetherapeutic agent nature of ultrasound energy and characteristics of microbubbles

While using ultrasound the microbubble formation reduces the

peak negative pressure required for enhanced drug delivery by actingas nuclei for cavitation thereby decreases the threshold of ultrasoundenergy required for this phenomenon The transport of drug is signi1047297-cantlyenhanced over diffusionalone by thepresenceof these oscillatingbubbles Stable oscillating bubbles create convection by evolution of circulating eddies around the oscillating bubble (microstreaming) andproduce a force acting on other suspended particles in the vicinity of an oscillating bubble(acoustic pressure) Theparticle is pushedtowardsthe bubble if it is denser than the surrounding liquid and vice versa[166] Most of the drug carriers such as micelles and liposomes beingdenserthan water areconvected towards thebubble andthusaugmentthe dispersive transport of the drug carrier The dispersive transport of the drug is further increased if the vesicle is drawn into the micro-streaming 1047297eld around the bubble and can be ruptured by high shear

rate thus releasing the drug Another key mechanism contributing to




ultrasound enhanced drug or gene delivery is related to the stressin1047298icted by cavitation events on tissue and cells The ultrasound-induced microbubble cavitation induces pore formation in the cellmembranes aiding the druggene deposition In a recent study Denget al [167] demonstrated ultrasound-induced increased transmem-brane current as a direct result of membrane resistance due to pore for-mation Microbubbles have another unique characteristic of increasedadherence to the damaged vascular endothelium This characteristicenables selectively concentrated delivery of drug or genes bound toalbumin-coated microbubbles at the vascular injury site [168]

One of the most promising clinical applications of sonoporationtechnologies is ef 1047297cient delivery of genetic material such as plasmidsand antisense oligonucleotides for gene therapy The process of genetransfection using ultrasound is known as ldquosonofectionrdquo The deliveryof genetic material to thetargettissue is trickybecause it hasto be tissuespeci1047297c and at thesame time it has to be protected from degradation by

DNase Since the ultrasound beam can be focused on a particular tissueultrasound-mediated gene delivery holds tremendous potential The1047297rst use of surface ultrasound in targeted DNA delivery was done in1996 using intravenously delivered microbubbles carrying antisenseoligonucleotide [169] Since then many studies both in vitro and invivo have described the ef 1047297cient use of ultrasound-mediated micro-bubble destruction by cavitation and subsequent cargo release forgene delivery [156170ndash177]

Another potential application of this technology is ultrasound-assisted delivery of large protein molecules such as regulatory hor-mones The delivery of large protein molecules is very complex com-pared to small molecular weight drugs because proteins are poorlydiffusible through solids and gels Therefore the lipid bilayer of cellmembrane prevents the transport of protein Current research is pri-

marily focused on transdermal delivery of insulin for diabetes andsome efforts for birth control hormones Recent studies have reportedincreased permeability of the skin by ultrasound with collapse cavita-tion as a causative mechanism [178ndash180] The ultrasound-inducedcavitation events cause opening of reversible channels in the lipid bi-layer of stratum corneum and thus easing the transport of proteinsinto the skin [181182] The ultrasound-induced delivery has beenused for other protein such as thrombolytic enzymes [183ndash185]and ultrasonic nebulization by the pulmonary route [186ndash188] Useof ultrasound for the potentiation of chemotherapeutic agent deliveryhas been recently explored Studies have suggested that ultrasoundhas synergistic effects withdrugs [159189190] dueto increased deliveryof the drugs to the tissues Further advancement has been made inultrasound-induced chemotherapeutic agent delivery by developing

molecular vehicles that can deliver the drug locally using ultrasound

stimulus at tumor site and thus reducing systemic side effects Twosuch carrier molecules for delivery of chemotherapeutic agents are lipo-somes [191ndash193] and micelles [194195]

Use of ultrasound-assisted targeted drug delivery technology isever-increasingin clinical medicine andresearch dueto itsusein deliveryof various therapeutic agents including genetic materials chemotherapydrugs and proteins In future this technique is believed to further ad-vance with improved ef 1047297cacy and reduced side effects

91 Sonodynamic therapy

Sonodynamic therapy (SDT) uses ultrasound and PDT agents insynchronization for activation SDT is a non-invasive and repeatableapproach using low-intensity ultrasound with a sonosensitizer for can-cer therapy [196] For instance PPIX produced from 5-aminolevulinic

acid (5-ALA)) is reported to be usefulwith low-intensity but focused ul-trasound in deep-seated glioma models [197] Also 5-ALA-inducedPPIX1047298uorescence has been used in malignant glioma in order to rendermore complete resection in surgical operations [198] Further variousnovel PS have been used for SDT such as a homogeneous complex of oligomers of hematoporphyrin called photofrin II a gallium porphyrincomplex ATX-70 a hydrophilic chlorin derivative A7X-S10 and anovel porphyrin derivative devoid of photosensitivity and DCPH-P-Na(I) [199] The mechanisms of action of SDT are still under investigationbutarebelievedto be based on eitherthe actionof PS nanoaggregates asnuclei for the formation of cavitation microbubbles that mechanicallydisrupt the cells or on the emission of small ldquo1047298ashesrdquo of light causedby collapse of cavitation microbubbles that are absorbed by the PS pro-ducing singlet oxygen that kills the cells as in PDT

The applications and properties of variousresonances frommagnetic1047298uorescence nuclear and surface plasmon play a signi1047297cant role in theenhancement and activation of SDT [200] Recently a triple-functionalcore-shell structured upconversion luminescent nanoparticles NaGdF(4)YbErCaF(2)SiO(2)-PS (hematoporphyrin and silicon phthalocya-ninedihydroxide) which possess a multifunctionalityin the1047297elds of PDTMRI and 1047298uorescenceluminescence imaging was developed to investi-gate the effect of PDT in vitro in HeLa cells using a 1047298uorescent probe Ithas low dark toxicity and could be a promising modality for PDT [201]Also another study showed caspase-3 activation in single cells withFRET that induces apoptosis through PDT [202] and complexes likeFe3O4SiO2 coreshell NP functionalized by phosphorescent iridiumhave been designed and synthesized thatmakes it well-suited forphos-phorescent labeling and simultaneous singlet oxygen generation to in-

duce apoptosis through PDT [203] Thus the effective use of various

Fig 9 Photothermal therapy PEGylated nanogels containing gold nanoparticles are uptaken by the cells Irradiation (both heat and light) kills the cancer cells




resonating techniques could provide a promising methodology forenhancing SDT

SDT opens a new arena of medical-activated sensitizer therapy[204] SDT makes use of sonosensitizers that are similar to photosensi-tizers but sensitive to ultrasound instead of light Recently Dai et alapplied theuseof sonosensitizersin combinationwithliposomes to tar-get chemotherapy drugs directly to tumor cells SDT withlow-intensityultrasound combined with a sonosensitizer proved to be a promising

approach to cancer therapy [205] Theeffects of combined sonodynamicand photodynamic therapies with photolon on a glioma C6 tumormodel were studied and found that the maximal tumor necrosis areathat underwent sonication followed by PDT at a dose of 100 Jcm2

was 100 in rats [206]

92 Limitations of acoustic mediated drug delivery

Being a veryactiveprocessthe consequences of ultrasound-mediatedtargeteddrugdeliverycould be detrimental forthe tissues[160166207]The ultrasonic cavitation bubble formation a requisite for helping thetransport of drugs into the cells and promoting the physical or chemicalrelease of drugs from the carrier is clearly not a healthy environmentfor the cells A certain intensity of cavitational activity is essential foreffective delivery of the drug Thus intensity of this cavitational activityshould be at a level suf 1047297cient enough to permeabilize the cells withoutdestroying them or a level that creates adequate microstreaming tobreak open drug carriers such as liposomes without damaging thehostcells However these shear forces and liquid micro-jetscould poten-tially damage the cell membrane The essential cellular biochemicalprocesses could be inhibited by free radical formation On the otherhand microbubbles with stable cavitation can potentially be bene1047297cialfor the cells by increasing the convection of nutrients and oxygen [208]Therefore there is an urgent need to further understand ultrasoundndash

microbubble interaction and cavitation physics Another pressing needis to develop better protected genetic material that is not degraded bythe action of enzymes or shear forces before it gets delivered to thetarget cells To bring ultrasound-assisted transdermal protein deliveryto the clinic further studies are required to conclusively understand

the effects of ultrasound on protein conformation and reveal the under-lying mechanism of enhanced transdermal protein delivery

Moreover acoustic cavitation increases cell permeability and facili-tates molecular internalization however it may also damage or evenkill the cells if the pores induced by cavitation are too large such thatthe cell membrane cannot reseal quickly [162] The problem is magni-1047297ed for the effective delivery of large molecules such as plasmid DNAwhich requires that suf 1047297ciently large pores are created on the cell sur-face but which risks that thedisrupted cell membrane will lose vital cy-toplasmic compounds resulting in cell death Moreover it appears thatthecells returnalmost immediately to an impermeable state after ultra-sound exposure (Fig 10) suggesting that sonoporation is a transientphenomenon with pore opening lasting on the order of millisecondsto seconds

10 Theranostics

Drug standardization protocols andthe prevailing concept of universalor generalized medicine have caused a lot of problems in the past for thedrug companies as well as consumers research and common-sense ideasraise a lot of questions onthe credibilityof the current medical systemasawhole Questions like ldquowhy use common medicines for everyone whenindividual genotypes are differentrdquo are raised Scientists and physiciansare increasingly orienting their research towards the use of personalizedmedicine Theranostics aims to develop such an idea of personalizedmedicine intended for a speci1047297c individuals illness by understandingthe cellular phenotype(s) and heterogeneity of the target [209210]in the individuals body and designing an individualized treatment

Coined by Funkhouser [211] theranostics describes a multimodal

functionalized system that functions at the molecular level [212] asshown in Fig 11 Any of the physical methods described above can beused for porating and concentrating the drugs in therapeutic strategiessuch as drug gene nucleic acid delivery and chemotherapy and activat-ed by hyperthermiaphotothermal ablation or PDT which are combinedwith one or more imaging functionalities for both in vitro and in vivostudies

For instance recently PDT has been used as a theranostics modality

for various cancers and diseases [213] With the use of highly tumor-speci1047297c albumin NP as ef 1047297cient therapeutic agents and photodynamicimaging (PDI) reagents in cancer treatment hydrophobic photosensi-tizer chlorin(e6) (Ce6) was 1047297rst chemically conjugated to humanserum albumin (HSA) [214] Next upon illumination with the appropri-ate wavelength of light the conjugate produced singlet oxygen and dam-aged target tumor cells in a cell culture system

The progress of novel theranostic approaches based on carbonnanostructure is attractive in the 1047297eld of nanomedicine The inherentoptical properties such as 1047298uorescence make carbon nanostructuresuseful contrast agents in optical imaging and sensing [215216]Functionalization of SWCNT with different moieties enables targetingand imaging therapy One of the most interesting examples of suchmultimodal SWCNT constructs is carrying a 1047298uorescein probe togetherwith the antifungal drug amphotericin B or 1047298uorescein and the anti-tumor agent methotrexate [217] Fullerenes have shown potentialapplications in several different cancer therapeutic approaches such asPDT photothermal treatment radiotherapy and chemotherapy whichcan also serve as novel contrast agents in MRI [218] The authorsperformed extensive research on PDT and emphasized on the applica-tion of fullerenes in various studies [219ndash221] Similarly graphenemonolayers have also aroused widespread interest in the applicationsof biomedicine [222] Unique physical and surface features of carbon-based nanomaterials make them a key player in the 1047297eld of nano-medicine Besides all its wide application in theranostics still moreresearch needs to be carried outon these materials to explore the inter-action of such multifunctional and combinational therapy in both invitro and in vivo applications

11 Conclusions

The use of physical energy methods for enhancing drug and genedelivery is a good example of the type of multi-disciplinary collabora-tions that have become increasingly common in the modern era of personalized medicine and nanomedicine Many of the interactions be-tween physical energy and cells or tissues take place on the nano-scaleand need to be studied and optimized using nanotechnology techniquesA common unifying motif in many (if not most) of these applications isthe creation of temporary pores or channels in the plasma membranesof cells or in thestratum corneum of skin Thedesired therapeutic mole-cules (drugs or DNA) pass through these pores or channels sometimesdriven by gradients produced by the applied energy differential Thesepores and channels should be self-sealing in other words they should

stay open long enough to allow the therapeutic cargo to pass throughbut not stay open long enough to cause cell death or tissue injuryMany of the nanocarriers used for drug and gene delivery are consider-ably more ef 1047297cient if they can be disrupted at their desired site of actionthusreleasing their drugcargo in a predictablecontrolled mannerratherthan relying on the natural release mechanisms that may increasenon-targeted drug distribution Since many physical energy modalitiescan be spatially focused onto the tumor or other target tissue theyhave been extensively used for drug release or drug activation Magneticand thermal energy can be further used to concentrate systemicallyadministereddrugsor drug carriersin thedesiredanatomicalarea by ex-ternal application of the energy Potential clinical applications of thesetechnologies will however be complicated by their multidisciplinarynature Oneotherlimitationis that unless anduntillocationof theaffect-

ed region is known with a high spatial resolution the use of physical




Fig 10 Sonoporation Liposomebound drugis delivered to the desired site Ultrasound-sensitive liposomes burst openupon exposure to ultrasound leading to effective local deliveryof the drug

Fig 11 Nanoplatforms with theranostic functionalities Fe2O3 magnetic NP photosensitizer appropriate polymeric coating surface-charge tuning groups optical imaging dyes

targeting agents adsorbedbonded drugs sensitive coverage DNA and other nucleic acids polyethylene glycol proteins and MRI active agents




energy may not be as applicable By de1047297nition these technologies willbedrug-device combinations which historically have been much harder toprogress to regulatory approval than drugs or devices aloneWith thein-troduction of nanocarriers into the picture the path to regulatory ap-proval becomes even more complicated Nevertheless the relentlessgrowth in biomedical researchbased on nanomedicinewillundoubtedlycontinue and physical energy modalities are expected to be increasinglyinvolved in these efforts

Acknowledgments

This work was supported by the US NIH (R01AI050875 to MRH)

References

[1] OMKoo I Rubinstein H OnyukselRole of nanotechnologyin targeteddrug deliveryand imaging a concise review J Nanomed Nanotechnol 1 (2005) 193ndash212

[2] G Poste R Kirsh Site-speci1047297c (targeted) drug delivery in cancer therapy NatBiotechnol 1 (1983) 869ndash878

[3] KK Jain Drug delivery systems in JM Walker (Ed) Method Mol Biol HumanaPress Totowa NJ 2008 pp 1ndash251

[4] M Hofmann-Amtenbrink Bv Rechenberg H Hofmann SupermagneticNanoparticles for Biomedical Application Transworld ResearchNetwork TrivandrumKerala India 2009

[5] A Gupta P Avci M Sadasivam R Chandran N Parizotto D Vecchio WCMA

de Melo T Dai LY Chiang MR Hamblin Shining light on nanotechnology tohelp repair and regeneration Biotechnol Adv (2012)

[6] X Huang YJ Chen DY Peng QL Li XS Wang DL Wang WD Chen Solidlipid nanoparticles as delivery systems for gambogenic acid Colloids Surf B102 (2013) 391ndash397

[7] A Puri K Loomis B Smith JH Lee A Yavlovich E Heldman R BlumenthalLipid-based nanoparticles as pharmaceuticaldrug carriers from concepts to clinicCrit Rev Ther Drug 26 (2009) 523ndash580

[8] HM Aliabadi A Lavasanifar Polymeric micelles for drug delivery Expert OpinDrug Deliv 3 (2006) 139ndash162

[9] GS Kwon T Okano Polymeric micelles as new drug carriers Adv Drug DelivRev 21 (1996) 107ndash116

[10] JO Kim NV Nukolova HS Oberoi AV Kabanov TK Bronich Block ionomercomplex micelles with cross-linked cores for drug delivery Polym Sci Ser APolym Phys 51 (2009) 708ndash718

[11] N Pothayee N Pothayee N Jain N Hu S Balasubramaniam LM Johnson RMDavis N Sriranganathan JSRif 1047298e Magnetic blockionomer complexes for potentialdual imaging and therapeutic agents Chem Mater 24 (2012) 2056ndash2063

[12] AK Patri JF Kukowska-Latallo JR Baker Jr Targeted drug delivery withdendrimers comparison of the release kinetics of covalently conjugated drugand non-covalent drug inclusion complex Adv Drug Deliv Rev 57 (2005)2203ndash2214

[13] M Sun A Fan Z Wang Y Zhao Dendrimer-mediated drug delivery to the skinSoft Matter 8 (2012) 4301ndash4305

[14] M Liong J Lu M Kovochich T Xia SG Ruehm AE Nel F Tamanoi JI ZinkMultifunctional inorganic nanoparticles for imaging targeting and drug deliveryACS Nano 2 (2008) 889ndash896

[15] A Fornara A Recalenda J Qin A Sugunan F Ye S Laurent RN Muller J ZouAR Usama MS Toprak M Muhammed Polymericinorganic multifunctionalnanoparticlesfor simultaneousdrug delivery and visualization MRS Online Proceed-ings Library 1257 2010 (0-0)

[16] C Zhang C Li S Huang Z Hou Z Cheng P Yang C Peng J Lin Self-activatedluminescentand mesoporousstrontium hydroxyapatite nanorods for drugdeliveryBiomaterials 31 (2010) 3374ndash3383

[17] T Niidome M Yamagata Y Okamoto Y Akiyama H Takahashi T Kawano YKatayama Y Niidome PEG-modi1047297ed gold nanorods with a stealth characterfor in vivo applications J Control Release 114 (2006) 343ndash347

[18] L Qi X Gao Emerging application of quantum dots for drug delivery and therapyExpert Opin Drug Deliv 5 (2008) 263ndash267[19] M Ozkan Quantum dots and other nanoparticles what can they offer to drug

discovery Drug Discov Today 9 (2004) 1065ndash1071[20] Z Liu K Chen C DavisS SherlockQ Cao X Chen H Dai Drug delivery with carbon

nanotubes for in vivo cancer treatment Cancer Res 68 (2008) 6652ndash6660[21] TA Hilder JM Hill Carbon nanotubes as drug delivery nanocapsules Curr

Appl Phys 8 (2008) 258ndash261[22] IISlowing BGTrewyn S Giri VSY LinMesoporous silica nanoparticles fordrug

delivery and biosensing applications Adv Funct Mater 17 (2007) 1225ndash1236[23] C Wang L Cheng Z Liu Drug delivery with upconversion nanoparticles for

multi-functional targeted cancer cell imaging and therapy Biomaterials 32(2011) 1110ndash1120

[24] DK Chatterjee LS Fong Y Zhang Nanoparticles in photodynamic therapy anemerging paradigm Adv Drug Deliv Rev 60 (2008) 1627ndash1637

[25] WW Yu E Chang R Drezek VL Colvin Water-soluble quantum dots for bio-medical applications Biochem Biophys Res Commun 348 (2006) 781ndash786

[26] M De PS Ghosh VM Rotello Applications of nanoparticles in biology AdvMater 20 (2008) 4225ndash4241

[27] R Duncan Drug-polymer conjugates potential for improved chemotherapyAnti Cancer Drugs 3 (1992) 175ndash210

[28] G Giani S Fedi R Barbucci Hybrid magnetic hydrogel a potential system forcontrolled drug delivery by means of alternating magnetic 1047297elds Polymers 4(2012) 1157ndash1169

[29] R Asmatulu A Fakhari HL Wamocha HY Chu YY Chen MM Eltabey HHHamdeh JC Ho Drug-carrying magnetic nanocomposite particles for potentialdrug delivery systems J Nanotechnol 2009 (2009) 1ndash6

[30] DG Kassan AM Lynch MJ Stiller Physical enhancement of dermatologic drugdelivery iontophoresis and phonophoresis J Am Acad Dermatol 34 (1996)657ndash666

[31] MR Prausnitz S Mitragotri R Langer Current status and future potential of transdermal drug delivery Nat Rev Drug Discov 3 (2004) 115ndash124[32] M Golzio MP Rols J Teissie In vitro and in vivo electric 1047297eld-mediated perme-

abilization gene transfer and expression Methods 33 (2004) 126ndash135[33] SR Best S Peng CM Juang CF Hung D Hannaman JR Saunders TC Wu SI

Pai Administration of HPV DNA vaccine via electroporation elicits the strongestCD8+ T cell immune responses compared to intramuscular injection and intra-dermal gene gun delivery Vaccine 27 (2009) 5450ndash5459

[34] AKRoosS Moreno C LederM PavlenkoA King P Pisa Enhancementof cellularimmune response to a prostate cancer DNA vaccine by intradermal electropora-tion Mol Ther 13 (2006) 320ndash327

[35] PG Kyrtatos P Lehtolainen M Junemann-Ramirez A Garcia-Prieto AN Price JF Martin DG Gadian QA Pankhurst MF Lythgoe Magnetic tagging in-creases delivery of circulating progenitors in vascular injury JACC CardiovascInterv 2 (2009) 794ndash802

[36] Z Medarova W Pham C Farrar V Petkova A Moore In vivo imaging of siRNAdelivery and silencing in tumors Nat Med 13 (2007) 372ndash377

[37] G Chu H Hayakawa P Berg Electroporation for the ef 1047297cient transfection of mammalian cells with DNA Nucleic Acids Res 15 (1987) 1311ndash1326

[38] JM Escoffre T Portet L Wasungu J Teissie D Dean MP Rols What is (Stillnot) known of the mechanism by which electroporation mediates gene transferand expression in cells and tissues Mol Biotechnol 41 (2009) 286ndash295

[39] A Ostrow Transdermal magnetic delivery system and method in US Patents(Ed) US United States 2002 pp 1-11

[40] D Liu L Wang Z Wang A Cuschieri Magnetoporation and magnetolysis of cancer cells via carbon nanotubes induced by rotating magnetic 1047297elds NanoLett 12 (2012) 5117ndash5121

[41] H Pan Y Zhou F Sieling J Shi J Cui C Deng Sonoporation of cells for drug andgene delivery Engineering in Medicine and Biology Society 2004 IEMBS 0426th Annual International Conference of the IEEE 2004 pp 3531ndash3534

[42] Y Zhou Ultrasound-mediated druggene delivery in solid tumor treatment J Health Eng 4 (2013) 223ndash254

[43] Z Yanyan CB Ballas MP Rao Towards ultrahigh throughput microinjectionMEMS-based massively-parallelized mechanoporation Engineering in Medicineand Biology Society (EMBC) 2012 Annual International Conference of the IEEE2012 pp 594ndash597

[44] H Yueh-Ling Effects of ultrasound anddiclofenacphonophoresis on in1047298ammatorypain relief suppression of inducible nitric oxide synthase in arthritic rats PhysTher 86 (2006) 39ndash49

[45] P Tyle P Agrawala Drug deliveryby phonophoresis PharmRes 6 (1989)355ndash361[46] P Soman W Zhang A Umeda ZJ Zhang S Chen Femtosecond laser-assisted

optoporation for drug and gene delivery into single mammalian cells J BiomedNanotechnol 7 (2011) 1ndash8

[47] L Gu SK Mohanty Targetedmicroinjection intocells and retina using optoporation J Biomed Opt 16 (2011) 128003

[48] D Popescu I Stelian AG Popescu N Neacsu ML Flonta The effect of lipidbilayer hydration on transbilayer pores appearance Romanian J Biophys 16(2006) 39ndash56

[49] SI Dumitru Popescu Aurel Popescu Liviu Movileanu Planar lipid bilayers(BLMs) and their applications in HT Tien A Ottava-Leitmannova (Eds) ElasticProperties of Bilayer Lipid Membranes and Pore Formation Elsevier Scince BVNetherlands 2003 p 174

[50] TJ Kardos Method of Contactless Magnetic Electroporation in US Patents(Ed) CA US 2010 pp 1-9

[51] N Nishiyama Y Bae K Miyata S Fukushima K Kataoka Smart polymeric mi-celles for gene and drug delivery Drug Discov Today Technol 2 (2005) 21 ndash26

[52] MR Hamblin T Hasan Photodynamic therapy a new antimicrobial approachto infectious disease Photochem Photobiol Sci 3 (2004) 436ndash450[53] MR Hamblin E Luke Newman New trends in photobiology on the mechanism

of the tumour-localising effect in photodynamic therapy J Photochem PhotobiolB 23 (1994) 3ndash8

[54] X Huang P Jain I El-Sayed M El-Sayed Plasmonic photothermal therapy(PPTT) using gold nanoparticles Lasers Med Sci 23 (2008) 217ndash228

[55] SSKelkar TMReineke Theranosticscombining imaging andtherapy BioconjugChem 22 (2011) 1879ndash1903

[56] Z Liu XJ Liang Nano-carbons as theranostics Theranostics 2 (2012) 235ndash237[57] P Agostinis K Berg KA Cengel TH Foster AW Girotti SO Gollnick SM

Hahn MR Hamblin A Juzeniene D Kessel M Korbelik J Moan P Mroz DNowis J Piette BC Wilson J Golab Photodynamic therapy of cancer an updateCA Cancer J Clin 61 (2011) 250ndash281

[58] TG St Denis T Dai L Izikson C Astrakas RR Anderson MR Hamblin GPTegos All you need is light antimicrobial photoinactivation as an evolvingand emerging discovery strategy against infectious disease Virulence 2 (2011)

[59] J Glaeser AM Nuss BA Berghoff G Klug Singlet oxygen stress in microorgan-isms Adv Microb Physiol 58 (2011) 141ndash173




[60] AKA Silva ELd Silva EE Oliveira EST Egito AS Carrico Polymericsuperparamagnetic carriers as potential drug delivery systems PublICa 1(2005) 8ndash15

[61] AS Luumlbbe C Alexiou C Bergemann Clinical applications of magnetic drugtargeting J Surg Res 95 (2001) 200ndash206

[62] C Alexiou R Jurgons RJ Schmid C Bergemann J Henke W Erhard EHuengesF Parak MagneticDrugtargetingmdashbiodistributionof the magneticcarrierand the chemotherapeutic agent mitoxantrone after locoregional cancer treat-ment J Drug Target 11 (2003) 139ndash149

[63] J Dobson Magnetic nanoparticle for drug delivery Drug Dev Res 67 (2006)1ndash2

[64] D Upadhyay S Scalia R Vogel N Wheate R Salama P Young D Traini WChrzanowski Magnetised thermo responsive lipid vehicles for targeted andcontrolled lung drug delivery Pharm Res 29 (2012) 2456ndash2467

[65] SL McGill CL Cuylear NL Adolphi M Osinski HDC Smyth Magnetically re-sponsive nanoparticles for drug delivery applications using low magnetic 1047297eldstrengths nanobioscience IEEE Trans 8 (2009) 33ndash42

[66] SC McBain HHYiu J Dobson Magnetic nanoparticles forgene and drug deliveryInt J Nanomedicine 3 (2008) 169ndash180

[67] J Chomoucka J Drbohlavova D Huska V Adam R Kizek J Hubalek Magneticnanoparticles and targeted drug delivering Pharmacol Res 62 (2010) 144ndash149

[68] JW Haverkort S Kenjeres Optimizing drug delivery using non-uniformmagnetic 1047297elds a numerical study in JV Sloten P Verdonck M Nyssen

J Hauei sen (Eds ) ECIFM BE 2008 Sprin ger- Verla g Berli n Heide lberg Heidelberg 2008 pp 2623ndash2627

[69] AP Graham GS Duesberg W Hoenlein F Kreupl M Liebau R Martin BRajasekharan W Pamler R Seidel W Steinhoegl E Unger How do carbonnanotubes 1047297t into the semiconductor roadmap Appl Phys A 80 (2005)1141ndash1151

[70] YY Xiong Study on photodynamic therapy for HL60 cells inactivation by visible

light-induced Fe-doped nano-TiO2 under magnetic 1047297eld Adv Mater Res 136(2010)

[71] F Scherer M Anton U Schillinger J Henke C Bergemann A Kruger BGansbacher C Plank Magnetofection enhancing and targeting gene deliveryby magnetic force in vitro and in vivo Gene Ther 9 (2002) 102ndash109

[72] T Neuberger B Schoumlpf H Hofmann M Hofmann B von RechenbergSuperparamagnetic nanoparticles for biomedical applications possibilities andlimitations of a new drug delivery system J Magn Magn Mater 293 (2005)483ndash496

[73] YH Lien TM Wu The application of thermosensitive magnetic nanoparticles indrug delivery Adv Mater Res 47ndash50 (2008) 528ndash531

[74] M Vicente-Manzanares F nchez-Madrid Cell polarization a comparative cellbiology and immunological view Dev Immunol 7 (2000) 51ndash65

[75] A Huttenlocher Cell polarization mechanisms during directed cell migrationNat Cell Biol 7 (2005) 336ndash337

[76] DC Chang Cell poration and cell fusion using an oscillating electric 1047297eldBiophys J 56 (1989) 641ndash652

[77] LV Chernomordik SI Sukharev SV Popov VF Pastushenko AV Sokirko IGAbidor YA Chizmadzhev The electrical breakdown of cell and lipid mem-branes the similarity of phenomenologies Biochim Biophys Acta 902 (1987)360ndash373

[78] AJ Grodzinsky Electromechanical and physicochemical properties of connec-tive tissue Crit Rev Biomed Eng 9 (1983) 133ndash199

[79] SN Murthy YL Zhao A Sen SW Hui Cyclodextrin enhanced transdermaldeliveryof piroxicam andcarboxy1047298uorescein by electroporationJ ControlRelease99 (2004) 393ndash402

[80] JF Huang KC Sung OY Hu JJ Wang YH Lin JY Fang The effects of electri-cally assisted methods on transdermal delivery of nalbuphine benzoate andsebacoyl dinalbuphine ester from solutions and hydrogels Int J Pharm 297(2005) 162ndash171

[81] AV Badkar AM Smith JA Eppstein AK Banga Transdermal delivery of inter-feron alpha-2B using microporation and iontophoresis in hairless rats PharmRes 24 (2007) 1389ndash1395

[82] TW Wong YL Zhao A Sen SW Hui Pilot study of topical delivery of methotrexateby electroporation Br J Dermatol 152 (2005) 524ndash530

[83] Y Tokudome K SugibayashiMechanismof thesynergic effects of calciumchlorideand electroporation on the in vitro enhanced skin permeation of drugs J Control

Release 95 (2004) 267ndash

274[84] M Nishikawa M Yamauchi K Morimoto E Ishid Y Takakura M HashidaHepatocyte-targeted in vivo gene expression by intravenous injection of plasmidDNA complexed with synthetic multi-functional gene delivery system GeneTher 7 (2000) 548ndash555

[85] LC Heller MJ Jaroszeski D Coppola AN McCray J Hickey R Heller Optimi-zation of cutaneous electrically mediated plasmid DNA delivery using novelelectrode Gene Ther 14 (2007) 275ndash280

[86] V Preat Drug and gene delivery using electrotransfer Ann Pharm Fr 59 (2001)239ndash244

[87] S ChesnoyL Huang Enhancedcutaneous gene deliveryfollowing intradermal injection of naked DNA in a high ionic strength solution Mol Ther 5 (2002) 57ndash62

[88] DA Dean D Machado-Aranda K Blair-Parks AV Yeldandi JL Young Electro-poration as a method for high-level nonviral gene transfer to the lung GeneTher 10 (2003) 1608ndash1615

[89] R Zhou JE Norton DA Dean Electroporation-mediated gene delivery to thelungs Methods Mol Biol 423 (2008) 233ndash247

[90] IA Pringle G McLachlan DD Collie SG Sumner-Jones AE Lawton PTennant A Baker C Gordon R Blundell A Varathalingam LA Davies RA

Schmid SH Cheng DJ Porteous DR Gill SC Hyde Electroporation enhancesreporter gene expression following delivery of naked plasmid DNA to the lung

J Gene Med 9 (2007) 369ndash380[91] R Vanbever E LeBoulenge V Preat Transdermal delivery of fentanyl by elec-

troporation I In1047298uence of electrical factors Pharm Res 13 (1996) 559ndash565[92] AR Denet V Preat Transdermal delivery of timolol by electroporation through

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[94] R Zhou DA Dean Gene transfer of interleukin 10 to the murine cornea using

electroporation Exp Biol Med (Maywood) 232 (2007) 362ndash

369[95] K Blair-Parks BC Weston DA Dean High-level gene transfer to the corneausing electroporation J Gene Med 4 (2002) 92ndash100

[96] K Echeverri EM Tanaka Electroporation as a tool to study in vivo spinal cordregeneration Dev Dyn 226 (2003) 418ndash425

[97] CR Lin MH Tai JT Cheng AK Chou JJ Wang PH Tan M Marsala LC YangElectroporation for direct spinal gene transfer in rats Neurosci Lett 317 (2002)1ndash4

[98] B Hargrave H Downey R Strange Jr L Murray C Cinnamond C Lundberg AIsrael YJ Chen W Marshall Jr R Heller Electroporation-mediated gene transferdirectly to the swine heart Gene Ther 20 (2013) 151ndash157

[99] EL Ayuni A Gazdhar MN Giraud A Kadner M Gugger M Cecchini T CausTP Carrel RA Schmid HT Tevaearai In vivo electroporation mediated genedelivery to the beating heart PLoS One 5 (2010) e14467

[100] TL Ellis PA Garcia JH Rossmeisl Jr N Henao-Guerrero J Robertson RVDavalos Nonthermal irreversible electroporation for intracranial surgical appli-cations Laboratory investigation J Neurosurg 114 (2011) 681ndash688

[101] PA Garcia JH Rossmeisl Jr RE Neal II TL Ellis JD Olson N Henao-Guerrero J Robertson RV Davalos Intracranial nonthermal irreversible electroporation

in vivo analysis J Membr Biol 236 (2010) 127ndash136[102] RE Neal II JH Rossmeisl Jr PA Garcia OI Lanz N Henao-Guerrero RV

Davalos Successful treatment of a large soft tissue sarcoma with irreversibleelectroporation J Clin Oncol 29 (2011) e372ndashe377

[103] S Yao DL Gutierrez S Ring D Liu GE Wise Electroporation to deliver plasmidDNA into rat dental tissues J Gene Med 12 (2010) 981ndash989

[104] S Yao S Rana D Liu GE Wise Electroporation optimization to deliver plasmidDNA into dental follicle cells Biotechnol J 4 (2009) 1488ndash1496

[105] E Neumann M Schaefer-Ridder Y Wang PH Hofschneider Gene transfer intomouse lyoma cells by electroporation in high electric 1047297elds EMBO J 1 (1982)841ndash845

[106] LH Peng SY Tsang Y Tabata JQ Gao Genetically-manipulated adult stemcells as therapeutic agents and gene delivery vehicle for wound repair and re-generation J Control Release 157 (2012) 321ndash330

[107] A Zhou M Liu C Baciu B Gluumlck H Berg Membrane electroporation increasesphotodynamic effects J Electroanal Chem 486 (2000) 220ndash224

[108] M Lambreva B Gluumlck M Radeva H Berg Electroporation of cell membranessupporting penetration of photodynamic active macromolecular chromophoredextrans Bioelectrochemistry 62 (2004) 95ndash98

[109] YS Juan Xu Junjie Huang Chunmei Chen Guoyuan Liu Yan Jiang Yaomin ZhaoZhiyu Jiang Photokilling cancer cells using highly cell-speci1047297c antibodyndashTiO2bioconjugates and electroporation Bioelectrochemistry 71 (2007) 217ndash222

[110] NY Sardesai B Weiner Electroporation delivery of DNA vaccines prospects forsuccess Curr Opin Immunol 23 (2011) 421ndash429

[111] AR Boccaccini R Ma Y Li I Zhitomirsky Electrophoretic deposition of bioma-terials J R Soc Interface 7 (2010)

[112] A Sen YL Zhao SW Hui Saturated anionic phospholipids enhance transder-mal transport by electroporation Biophys J 83 (2002) 2064ndash2073

[113] B Rubinsky G Onik P Mikus Irreversible electroporation a new ablationmodality mdash clinical implications Technol Cancer Res Treat 6 (2007) 1ndash12

[114] J Peng Y Zhao J Mai W Guo Y Xu Short noncoding DNA fragment improveef 1047297ciencies of in vivo electroporation-mediated gene transfer J Gene Med 14(2012) 563ndash569

[115] M Shoji K Katayama M Tachibana K Tomita F Sakurai K Kawabata HMizuguchi Intramuscular DNA immunization with in vivo electroporation in-duces antigen-speci1047297c cellular and humoral immune responses in both systemicand gut-mucosal compartments Vaccine 30 (2012) 7278ndash7285

[116] PY LeeS ChesnoyL Huang Electroporatic deliveryof TGF-β1 gene works syner-gistically with electric therapy to enhance diabetic wound healing in dbdb mice J Invest Dermatol 123 (2004) 791ndash798

[117] LC Heller R Heller Electroporation gene therapy preclinical and clinical trialsfor melanoma Curr Gene Ther 10 (2013) 312ndash317

[118] V Mannem C Nanjarapalle G Stagni Iontophoresis of amoxicillin andcefuroxime rapid therapeutic concentrations in skin Drug Dev Ind Pharm(2013) 1ndash5

[119] K Malinovskaja T Laaksonen K Kontturi J Hirvonen Ion-exchange andiontophoresis-controlled delivery of apomorphine Eur J Pharm Biopharm(2013)

[120] HS Minkowitz Fentanyl iontophoretic transdermal system a review Tech RegAnesth Pain Manag 11 (2007) 3ndash8

[121] S Silber BM Richartz Evidence-based application of cardiac magnetic resonanceand computed tomography for primary diagnosisof stable coronaryartery diseasewith special attention to disease management program and the German NationalMedical Care Guidelines Herz 32 (2007) 139ndash158

[122] N Dixit V Bali S Baboota A Ahuja J Ali Iontophoresis mdash an approach for con-trolled drug delivery a review Curr Drug Deliv 4 (2007) 1ndash10




[123] ND Singh AK Banga Controlled delivery of ropinirole hydrochloridethrough skin using modulated iontophoresis and microneedles J DrugTarget 21 (2013) 354ndash366

[124] K Mizutani D Watanabe Y Akita M AkimotoY Tamada Y MatsumotoPhotody-namic therapyusing direct-current pulsed iontophoresis for 5-aminolevulinicacidapplication Photodermatol Photoimmunol Photomed 25 (2009) 280ndash282

[125] K Togsverd-Bo CS Haak D Thaysen-Petersen HC Wulf RR Anderson MHaeligdesdal Intensi1047297ed photodynamic therapy of actinic keratoses with fractionalCO2 laser a randomized clinical trial Br J Dermatol 166 (2012) 1262ndash1269

[126] CS Haak WA Farinelli J Tam AG Doukas RR Anderson M Haeligdersdal Frac-tional laser-assisted delivery of methyl aminolevulinate impact of laser channel

depth and incubation time Lasers Surg Med 44 (2012) 787ndash

795[127] B Forster A Klein RM Szeimies T Maisch Penetration enhancement of twotopical 5-aminolaevulinic acid formulations for photodynamic therapy by erbiumYAG laser ablation of the stratum corneum continuous versus fractional ablationExp Dermatol 19 (2010) 806ndash812

[128] WR Lee SC Shen KH Wang CH Hu JY Fang Lasers and microdermabrasionenhance and control topical delivery of vitamin C J Invest Dermatol 121(2003) 1118ndash1125

[129] H Schneckenburger A Hendinger R Sailer WSL Strauss M SchmittLaser-assisted optoporation of single cells J Biomed Opt 7 (2002) 410ndash416

[130] JC Kennedy RH PottierEndogenous protoporphyrin IX a clinically useful pho-tosensitizer for photodynamic therapy J Photochem Photobiol B 14 (1992)275ndash292

[131] S Fijan H HonigsmannB Ortel Photodynamic therapy of epithelial skin tumoursusing delta-aminolaevulinic acid and desferrioxamine Br J Dermatol 133 (1995)282ndash288

[132] S Grapengiesser M Ericson F Gudmundsson O Larko A Rosen AMWennberg Pain caused by photodynamic therapy of skin cancer Clin ExpDermatol 27 (2002) 493ndash497

[133] Y JiSK Powers JTBrown D Walstad L Maliner Toxicityof photodynamictherapywith photofrin in the normal rat brain Lasers Surg Med 14 (1994) 219 ndash228

[134] Q Chen M Chopp L Madigan MO Dereski FW Hetzel Damage threshold of nor-mal rat brain in photodynamic therapy Photochem Photobiol 64 (1996) 163ndash167

[135] Q Chen BC Wilson MO Dereski MS Patterson M Chopp FW Hetzel Effectsof light beam size on 1047298uence distribution and depth of necrosis in super1047297ciallyapplied photodynamic therapy of normal rat brain Photochem Photobiol 56(1992) 379ndash384

[136] SH Dayan AR Shah TK Bhattacharyya K Ogrady S Ventrapragada Effects if low frequency ultrasound on epidermal and dermal structures A clinical andhistologic study Cosmetic Derm 19 (2006) 140ndash146

[137] J Conde J Rosa JC Lima PV Baptista Nanophotonics for molecular diagnosticsand therapy applications Int J Photoenergy 2012 (2012)

[138] IT Ivanov R Todorova I Zlatanov Spectro1047298uorometric and microcalorimetricstudy of the thermal poration relevant to the mechanism of thermohaemolysisInt J Hyperthermia 15 (1999) 29ndash43

[139] G Steacutephane F Eric B Jean-Baptiste G Patrick Yeast cell inactivation related tolocal heating induced by low-intensity electric 1047297elds with long-duration pulsesInt J Food Microbiol 113 (2007) 180ndash188

[140] G Jori JD Spikes Photothermal sensitizers possible use in tumor therapy JPhotochem Photobiol B 6 (1990) 93ndash101

[141] WR Chen RL Adams AK Higgins KE Bartels RE Nordquist Photothermaleffects on murine mammary tumors using indocyanine green and an 808-nmdiode laser an in vivo ef 1047297cacy study Cancer Lett 98 (1996) 169ndash173

[142] U Lindner RA Weersink MA Haider MR Gertner SR Davidson M Atri BCWilson A Fenster J Trachtenberg Image guided photothermal focal therapy forlocalized prostate cancer phase I trial J Urol 182 (2009) 1371ndash1377

[143] Y Gu WR Chen M Xia SW Jeong H Liu Effect of photothermal therapy onbreast tumor vascular contents noninvasive monitoring by near-infrared spec-troscopy Photochem Photobiol 81 (2005) 1002ndash1009

[144] H Liu D Chen F Tang G Du L Li X Meng W Liang Y Zhang X Teng Y LiPhotothermal therapy of Lewis lung carcinoma in mice using gold nanoshellson carboxylated polystyrene spheres Nanotechnology 19 (2008) 455101

[145] ES Day PA Thompson L Zhang NA Lewinski N Ahmed RA Drezek SMBlaney JL West Nanoshell-mediated photothermal therapy improves survivalin a murine glioma model J Neurooncol 104 (2011) 55ndash63

[146] BN Khlebtsov EV Pan1047297lova GS Terentyuk IL Maksimova AV Ivanov NG

Khlebtsov Plasmonicnanopowders for photothermal therapyof tumors Langmuir28 (2012) 8994ndash9002[147] M Everts V Saini JL Leddon RJ Kok M Stoff-Khalili MA Preuss CL Millican

G Perkins JM Brown H Bagaria DE Nikles DT Johnson VP Zharov DTCuriel Covalently linked Au nanoparticles to a viral vector potential for com-bined photothermal and gene cancer therapy Nano Lett 6 (2006) 587 ndash591

[148] B Jang Y Choi Photosensitizer-conjugated gold nanorods for enzyme-activatable1047298uorescence imaging and photodynamic therapy Theranostics 2 (2012)190ndash197

[149] WIChoi JYKimC KangCCByeon YH Kim GTaeTumor regressionin vivo byphotothermal therapybased on gold-nanorod-loaded functional nanocarriers ACSNano 5 (2011) 1995ndash2003

[150] WI Choi A Sahu YH Kim G Tae Photothermal cancer therapy and imagingbased on gold nanorods Ann Biomed Eng 40 (2012) 534ndash546

[151] M Oishi A Tamura T Nakamura Y Nagasaki A smart nanoprobe based on1047298uorescence-quenching PEGylated nanogels containing gold nanoparticles formonitoring the responseto cancer therapyAdv Funct Mater 19 (2009) 827ndash834

[152] F Zhou D Xing Z Ou B Wu DE Resasco WR Chen Cancer photothermaltherapy in the near-infrared region by using single-walled carbon nanotubes

J Biomed Opt 14 (2009) 021009

[153] MS Zhen Fan AK Singh D Senapati SA Khan PC Ray Multifunctionalplasmonic shell magnetic core nanoparticles for targeted diagnostics isola-tion and photothermal destruction of tumor cells ACS Nano 6 (2012)1065ndash1073

[154] A Gasselhuber MR Dreher A Partanen PS Yarmolenko D Woods BJ WoodD Haemmerich Targeted drug delivery by high intensity focused ultrasoundmediated hyperthermia combined with temperature-sensitive liposomes com-putational modelling and preliminary in vivo validation Int J Hyperthermia 28(2012) 337ndash348

[155] N Rapoport Ultrasound-mediated micellar drug delivery Int J Hyperthermia28 (2012) 374ndash385

[156] RV Shohet S Chen YT Zhou Z Wang RS Meidell RH Unger PA GrayburnEchocardiographic destruction of albumin microbubbles directs gene delivery tothe myocardium Circulation 101 (2000) 2554ndash2556

[157] A Lawrie AF Brisken SE Francis DC Cumberland DC Crossman CMNewman Microbubble-enhanced ultrasound for vascular gene delivery GeneTher 7 (2000) 2023ndash2027

[158] S Paliwal S Mitragotri Ultrasound-induced cavitation applications in drug andgene delivery Expert Opin Drug Deliv 3 (2006) 713ndash726

[159] K Tachibana T Uchida K Ogawa N Yamashita K Tamura Induction of cell-membrane porosity by ultrasound Lancet 353 (1999) 1409

[160] SB Barnett GR ter Haar MC Ziskin WL Nyborg K Maeda J Bang Currentstatus of research on biophysical effects of ultrasound Ultrasound Med Biol20 (1994) 205ndash218

[161] NN Byl The use of ultrasound as an enhancer for transcutaneous drug deliveryphonophoresis J Am Phys Ther Assoc 75 (2013) 539ndash553

[162] S Mehier-Humbert T Bettinger F Yan RH Guy Plasma membrane porationinduced by ultrasound exposure Implication for drug delivery J Control Release104 (2005) 213ndash222

[163] R Karsha1047297an PD Bevan R Williams S Samac PN Burns Sonoporation by

ultrasound-activated microbubble contrast agents effect of acoustic exposureparameters on cell membrane permeability and cell viability Ultrasound MedBiol 35 (2009) 847ndash860

[164] P Marmottant S Hilgenfeldt Controlled vesicle deformation and lysis by singleoscillating bubbles Nature 423 (2003) 153ndash156

[165] WL Nyborg Ultrasonic microstreaming and related phenomena Br J CancerSuppl 5 (1982) 156ndash160

[166] WL Nyborg Biological effects of ultrasound development of safety guidelinesPart II general review Ultrasound Med Biol 27 (2001) 301 ndash333

[167] CX Deng F Sieling H Pan J Cui Ultrasound-induced cell membrane porosityUltrasound Med Biol 30 (2004) 519ndash526

[168] TR Porter WL Hiser D Kricsfeld U Deligonul F Xie P Iversen S Radio Inhi-bition of carotid artery neointimal formation with intravenous microbubblesUltrasound Med Biol 27 (2001) 259ndash265

[169] TR Porter PL Iversen S Li F Xie Interaction of diagnostic ultrasound withsynthetic oligonucleotide-labeled per1047298uorocarbon-exposed sonicated dextrosealbumin microbubbles J Ultrasound Med 15 (1996) 577ndash584

[170] S Bao BD Thrall DL Miller Transfection of a reporter plasmid into culturedcells by sonoporation in vitro Ultrasound Med Biol 23 (1997) 953ndash959

[171] Y Taniyama K Tachibana K Hiraoka T Namba K Yamasaki N Hashiya MAoki T Ogihara K Yasufumi R Morishita Local delivery of plasmid DNAinto rat carotid artery using ultrasound Circulation 105 (2002) 1233ndash1239

[172] S Chen RV Shohet R Bekeredjian P Frenkel PA Grayburn Optimization of ultrasound parameters for cardiac gene delivery of adenoviral or plasmiddeoxyribonucleic acid by ultrasound-targeted microbubble destruction J AmColl Cardiol 42 (2003) 301ndash308

[173] C Teupe S Richter B Fisslthaler V Randriamboavonjy C Ihling I Fleming RBusse AM Zeiher S Dimmeler Vascular gene transfer of phosphomimetic en-dothelial nitric oxide synthase (S1177D) using ultrasound-enhanced destruc-tion of plasmid-loaded microbubbles improves vasoreactivity Circulation 105(2002) 1104ndash1109

[174] JR Lindner Microbubbles in medical imaging current applications and futuredirections Nat Rev Drug Discov 3 (2004) 527ndash532

[175] Y Manome M Nakamura T Ohno H Furuhata Ultrasound facilitates transduc-tion of naked plasmid DNA into colon carcinoma cells in vitro and in vivo HumGene Ther 11 (2000) 1521ndash1528

[176] AH Mesiwala L Farrell HJ Wenzel DL Silbergeld LA Crum HR Winn PD

Mourad High-intensity focused ultrasound selectively disrupts the blood-brainbarrier in vivo Ultrasound Med Biol 28 (2002) 389ndash400[177] CW Cho Y Liu WN Cobb TK Henthorn K Lillehei U Christians KY Ng

Ultrasound-induced mild hyperthermia as a novel approach to increase druguptake in brain microvessel endothelial cells Pharm Res 19 (2002) 1123ndash1129

[178] S Mitragotri D Blankschtein R Langer Ultrasound-mediated transdermal proteindelivery Science 269 (1995) 850ndash853

[179] S Mitragotri J Kost Low-frequency sonophoresis a noninvasive method of drug delivery and diagnostics Biotechnol Prog 16 (2000) 488ndash492

[180] A Tezel A SensJ Tuchscherer S Mitragotri Frequencydependence of sonophoresisPharm Res 18 (2001) 1694ndash1700

[181] S Mitragotri J Kost Low-frequency sonophoresis a review Adv Drug DelivRev 56 (2004) 589ndash601

[182] S Mitragotri DA Edwards D Blankschtein R Langer A mechanistic study of ultrasonically-enhanced transdermal drug delivery J Pharm Sci 84 (1995)697ndash706

[183] CW Francis PT Onundarson EL Carstensen A Blinc RS Meltzer K SchwarzVJ Marder Enhancement of 1047297brinolysis in vitro by ultrasound J Clin Invest 90(1992) 2063ndash2068




[184] V Suchkova EL Carstensen CW Francis Ultrasound enhancement of 1047297brinolysisat frequencies of 27 to 100 kHz Ultrasound Med Biol 28 (2002) 377ndash382

[185] CG Lauer R Burge DB Tang BG Bass ER Gomez BM Alving Effect of ultra-sound on tissue-type plasminogen activator-induced thrombolysis Circulation86 (1992) 1257ndash1264

[186] TKosugi S Saitoh N TamakiK Hanashiro K Nakahodo M NakamuraInhalationof platelet-activating factor increases respiratory resistance in rats determinationby means of an astograph under nonanesthetized conditions Laryngoscope 103(1993) 428ndash430

[187] MP Flament P Leterme A Gayot Study of the technological parameters of ultra-sonic nebulization Drug Dev Ind Pharm 27 (2001) 643ndash649

[188] MP Flament P Leterme A Gayot In1047298uence of the technological parameters of ultrasonic nebulisation on the nebulisation quality of alpha1 protease inhibitor(alpha1PI) Int J Pharm 189 (1999) 197ndash204

[189] A Singh SP Singh R Bamezai Modulatory in1047298uence of arecoline on the phyticacid-altered hepatic biotransformation system enzymes sulfhydryl content andlipid peroxidation in a murine system Cancer Lett 117 (1997) 1 ndash6

[190] T Yu K Hu J BaiZ Wang Reversal of adriamycin resistance in ovariancarcinomacell line by combination of verapamil and low-level ultrasound UltrasonSonochem 10 (2003) 37ndash40

[191] MD Bednarski JW Lee MRCallstrom KC Li In vivo target-speci1047297c delivery of macromolecular agents with MR-guided focused ultrasound Radiology 204(1997) 263ndash268

[192] SP Vyas R Singh RK Asati Liposomally encapsulated diclofenac forsonophoresis induced systemic delivery J Microencapsul 12 (1995) 149ndash154

[193] EC Unger TP McCreery RH Sweitzer VE Caldwell Y Wu Acoustically activelipospheres containing paclitaxel a new therapeutic ultrasound contrast agentInvest Radiol 33 (1998) 886ndash892

[194] JL Nelson BL Roeder JC Carmen F Roloff WG Pitt Ultrasonically activatedchemotherapeutic drug delivery in a rat model Cancer Res 62 (2002)

7280ndash7283[195] NYRapoport DA Christensen HD Fain L Barrows Z GaoUltrasound-triggered

drug targeting of tumors in vitro and in vivo Ultrasonics 42 (2004) 943ndash950[196] H Shibaguchi H Tsuru M Kuroki Sonodynamic cancer therapy a non-invasive

and repeatable approach using low-intensity ultrasound with a sonosensitizerAnticancer Res 31 (2011) 2425ndash2429

[197] T Ohmura T Fukushima H Shibaguchi S Yoshizawa T Inoue M Kuroki KSasakiS Umemura Sonodynamictherapy with 5-aminolevulinic acidand focusedultrasound for deep-seated intracranial glioma in rat Anticancer Res 31 (2011)2527ndash2533

[198] M Hefti G von Campe M Moschopulos A Siegner H Looser H Landolt5-aminolevulinic acid induced protoporphyrin IX 1047298uorescence in high-gradeglioma surgery a one-year experience at a single institution Swiss MedWkly 138 (2008) 180ndash185

[199] M Kuroki K Hachimine H Abe H Shibaguchi S Maekawa J Yanagisawa TKinugasa T Tanaka Y Yamashita Sonodynamic therapy of cancer using novelsonosensitizers Anticancer Res 27 (2007) 3673ndash3677

[200] L Li JF Zhao N Won H Jin S K im JY Chen Quantum dot mdash aluminum phtha-locyanine conjugates perform photodynamic reactions to kill cancer cells via 1047298uo-rescence resonance energy transfer (FRET) Nanoscale Res Lett 7 (2012) 386

[201] XF Qiao JC Zhou JW Xiao YF Wang LD Sun CH Yan Triple-functionalcore-shell structured upconversion luminescent nanoparticles covalentlygrafted with photosensitizer for luminescent magnetic resonance imaging andphotodynamic therapy in vitro Nanoscale 4 (2012) 4611ndash4623

[202] Y Wu D Xing S Luo Y Tang Q Chen Detection of caspase-3 activation in singlecells by 1047298uorescence resonance energy transfer during photodynamic therapy in-duced apoptosis Cancer Lett 235 (2006) 239ndash247

[203] CW LaiYHWang CH Lai MJYangCY ChenPTChou CS ChanY Chi YC Chen JK Hsiao Iridium-complex-functionalized Fe3O4SiO2 coreshell nanoparticles afacile three-in-one system in magnetic resonance imaging luminescence imagingand photodynamic therapy Small 4 (2008) 218ndash224

[204] JN Kenyon RJ Fuller TJ Lewis Activated cancer therapy using light and ultra-sound mdash a case series of sonodynamic photodynamic therapy in 115 patientsover a 4 year period Curr Drug Ther 4 (2012) 179ndash193

[205] ZJ Dai S Li J Gao XN Xu WF Lu S Lin XJ Wang Sonodynamic therapy(SDT) a novel treatment of cancer based on sonosensitizer liposome as a newdrug carrier Med Hypotheses 80 (2013) 300ndash302

[206] DA Tserkovsky EN Alexandrova VN Chalau YP Istomin Effects of combinedsonodynamic and photodynamic therapies with photolon on a glioma C6 tumormodel Exp Oncol 34 (2012) 332ndash335

[207] SB Barnett HD Rott GR ter Haar MC Ziskin K Maeda The sensitivity of biological tissue to ultrasound Ultrasound Med Biol 23 (1997) 805ndash812

[208] DM Skyba RJ Price AZ Linka TC Skalak S Kaul Direct in vivo visualizationof intravascular destruction of microbubbles by ultrasound and its local effectson tissue Circulation 98 (1998) 290ndash293

[209] JR McCarthy The future of theranostic nanoagents Nanomedicine (Lond) 4(2009) 693ndash695

[210] B Sumer J Gao Theranostic nanomedicine for cancer Nanomedicine (Lond) 3(2008) 137ndash140

[211] J Funkhouser Reintroducing pharma theranostic revolution Curr Drug Discov2 (2002) 17ndash19

[212] DY Lee KC Li Molecular theranostics a primer for the imaging professionalAJR Am J Roentgenol 197 (2011) 318ndash324

[213] F Vatansever R Chandran M Sadasivam LY Chiang MR HamblinMulti-functionality in theranostic nanoparticles is more always better JNanomed Nanotechnol 3 (2012) 1ndash5

[214] H Jeong M Huh SJ Lee H Koo I C Kwon SYJ Sy K KimPhotosensitizer-conjugated human serum albumin nanoparticles for effective

photodynamic therapy Theranostics 1 (2011) 230ndash

239[215] K Welsher Z Liu SP Sherlock JT Robinson Z Chen D Daranciang H Dai Aroute to brightly 1047298uorescent carbon nanotubes for near-infrared imaging inmice Nat Nanotechnol 4 (2009) 773ndash780

[216] X Wang C Wang L Cheng ST Lee Z Liu Noble metal coated single-walledcarbon nanotubes for applications in surface enhanced Raman scattering imagingand photothermal therapy J Am Chem Soc 134 (2012) 7414ndash7422

[217] M Prato K Kostarelos A Bianco Functionalized carbon nanotubes in drugdesign and discovery Acc Chem Res 41 (2008) 60ndash68

[218] Z Chen L Ma Y Liu C Chen Applications of functionalized fullerenes in tumortheranostics Theranostics 2 (2012) 238ndash250

[219] SK Sharma LY Chiang MR Hamblin Photodynamic therapy with fullerenes invivo reality or a dream Nanomedicine (Lond) 6 (2011) 1813ndash1825

[220] M Wang L Huang SK Sharma S Jeon S Thota FF Sperandio S Nayka JChang MR Hamblin LY Chiang Synthesis and photodynamic effect of newhighly photostable decacationically armed[60] and [70]fullerene decaiodidemonoadducts to target pathogenic bacteria and cancer cells J Med Chem 55(2012) 4274ndash4285

[221] S Thota M Wang S Jeon S Maragani MR Hamblin LY Chiang Synthesis and

characterization of positively charged pentacationic [60]fullerene monoadductsfor antimicrobial photodynamic inactivation Molecules 17 (2012) 5225ndash5243

[222] H Shen L Zhang M Liu Z Zhang Biomedical applications of grapheneTheranostics 2 (2012) 283ndash294

[223] RDP KT Joseph Method of Contactells Magnetic Electrporation in US Patent(Ed) MagneGene Inc US 2010

[224] R Rao S Nanda Sonophoresis recent advancements and future trends JPharm Pharmacol 61 (2009) 689ndash705

[225] G Oni SA Brown JM Kenkel Can fractional lasers enhance transdermal ab-sorption of topical lidocaine in an in vivo animal model Lasers Surg Med 44(2012) 168ndash174

[226] B Rubinsky Irreversible electroporation in medicine Technol Cancer Res Treat6 (2007) 255ndash259

[227] J Yi AJ Barrow N Yu BE OrsquoNeill Ef 1047297cient electroporation of liposomes dopedwith pore stabilizing nisin J Liposome Res (2013) 1ndash6

[228] X Chen H Lv M Ye S Wang E Ni F Zeng C Cao F Luo J Yan Novelsuperparamagnetic iron oxide nanoparticles for tumor embolization applica-tion preparation characterization and double targeting Int J Pharm 426(2012) 248ndash255

[229] G Ge H Wu F Xiong Y Zhang Z Guo Z Bian J Xu C Gu N Gu X Chen DYang The cytotoxicity evaluation of magnetic iron oxide nanoparticles onhuman aortic endothelial cells Nanoscale Res Lett 8 (2013) 215

[230] JR Lepock HE Frey H Bayne J Markus Relationship of hyperthermia-inducedhemolysis of human erythrocytes to the thermal denaturation of membraneproteins Biochimica et Biophyslca Acta 980 (1989) 191ndash201

[231] D Park H Ryu HS Kim Y-s Kim K-S Choi H Park J Seo Sonophoresis usingultrasound contrast agents for transdermal drug delivery an in vivo experimentalstudy Ultrasound Med Biol 38 (2012) 642ndash650

[232] VMJA Pahade VJ Kadam Sonophoresis an overview Int J Pharm Sci RevRes 3 (2010) 24ndash32

[233] JABBS Bloom RG Geronemus Ablative fractional resurfacing in topical drugdelivery an update and outlook Dermatol Surg 39 (2013) 839ndash848

[234] J Gehl Electroporation theory and methods perspectives for drug deliverygene therapy and research Acta Physiol Scand 177 (2003) 437 ndash447

[235] DPRTJ Kardos Contactless magneto-permeabilization for intracellular plasmidDNA delivery in-vivo Hum Vaccin Immunother 8 (2012) 1707ndash1713

[236] SN Rekha Rao Sonophoresis recent advancements and future trends J Pharm

Pharmacol 61 (2009) 689ndash

705[237] TK Joseph S Soughayer Stephen C Jacobson J Michael Ramsey Bruce JTromberg Nancy L Allbritton Characterization of cellular optoporation withdistance Anal Chem 72 (2000) 1342ndash1347

[238] J Baumgart L Humbert Eacute Boulais R Lachaine J-J Lebrun M MeunierOff-resonance plasmonicenhanced femtosecond laser optoporation and transfectionof cancer cells Biomaterials 33 (2012) 2345ndash2350

[239] JFG-MDJ Stevenson P Campbell K Dholakia Single cell optical transfection J R Soc Interface 7 (2010) 863ndash871




11 Conclusions 109Acknowledgments 111References 111

1 Introduction

The purpose of a drug delivery system (DDS) [12] is to devise amethod that enables delivery of a therapeutic agent that may havesub-optimal physicochemical properties in biological tissue thus en-hancing ef 1047297cacy and safety by controlling the rate time and releaseof the agent [3] Targeted DDS (TDDS) includes the administrationof the therapeutic substance the release of the active ingredientsfrom the DDS and the subsequent transport of the active ingredientsacross the biological membranes to the speci1047297c site of action oftenusing what is so called ldquosmart drug carriersrdquo or ldquosmart nanoparticles(NP)rdquo Smart NP can improve drug delivery mechanisms based ontheir particular formulations [45] NP used in such biomedical appli-cations include lipid-based NP (liposomes) [67] polymeric micelles[89] block ionomer complexes [1011] water-soluble synthetic poly-mers (dendrimers) [1213] inorganic [14] and polymeric NP [15]

nanorods [1617] quantum dots [1819] carbon nanotubes [2021]silica-based NP [22] metal and semiconductor NP upconversion NP[2324] self-illuminating NP [2526] and polymerndashdrug conjugates[27] However the main limitations of employing NP for drug deliveryare the following 1) the relatively small amount of drug that can belinked to each NP 2) the possibility of drug deactivation once it ischemically bound to the NP 3) the possibility of immediate uncon-trollable passive release (burst effect) and 4) NP agglomeration pro-ducing quick elimination from bloodstream by macrophages before

reaching the target cells [28] Most of these factors in turn require injec-tion of unnecessarily high concentrations of NP with potential systemic

toxic effects In orderto overcomesomeof these hurdlesphysical energymethods have been explored to enhance not only NP but also drug andgene delivery

The enhancement of effective drug delivery to the target achievedby the addition of physical energy to the traditional TDDS systems hasbeen widely explored in recent years [29ndash36] These techniques havethe potential to be used in different biological and medical applica-tions as an advanced TDDS that can minimize the current limitationsand unwanted effects Biophysical energy such as electric 1047297elds mag-netic 1047297elds ultrasound and mechanical forces light and temperaturegradients can act as enhancers for drug delivery Technique-speci1047297cterms have been associated with each form of physical energy suchas electroporation [3738] for electric current iontophoresis for electricpotential magnetoporation [3940] for magnetic 1047297eld sonoporation

[4142] mechanoporation [43] and phonophoresis [4445] for ultra-sound optoporation [4647] for pulsed light and thermoporation[4849] for temperature respectively (Fig 1) Table 1 summarizes all of the different types of physical energy used in this review for poratingthe cells The advantages and disadvantages of the techniques are ana-lyzed in the table Synergistic combinations of two or more physical en-ergies such as magnetic-electroporation [50] are also of special interestandhave been explored as a potentialsystem foreffectivedrug deliveryThe formation of temporary pores in the cell membrane achieved

Fig 1 Different physicalenergy modules usedfor drug delivery Drugdelivery enhancers suchas electroporation magnetoporation thermoporation sonoporationand optoporationare

illustrated

















Table 1


Porationattributes


Physicalenergy

















[231]



























F frac14 6πηrhv















are controlled











iontophoresis





























5 Iontophoresis















aluminumndash

garnet (ErYAG mdash

2940 nm) lasers

















































































10 Theranostics







11 Conclusions














Acknowledgments


References









































































































































































J Biomed Opt 14 (2009) 021009

















































































































Table 1


Porationattributes


Physicalenergy

















[231]



























F frac14 6πηrhv















are controlled











iontophoresis





























5 Iontophoresis















aluminumndash

garnet (ErYAG mdash

2940 nm) lasers

















































































10 Theranostics







11 Conclusions














Acknowledgments


References









































































































































































J Biomed Opt 14 (2009) 021009

























































































































F frac14 6πηrhv















are controlled











iontophoresis





























5 Iontophoresis















aluminumndash

garnet (ErYAG mdash

2940 nm) lasers

















































































10 Theranostics







11 Conclusions














Acknowledgments


References









































































































































































J Biomed Opt 14 (2009) 021009










































































































iontophoresis





























5 Iontophoresis















aluminumndash

garnet (ErYAG mdash

2940 nm) lasers

















































































10 Theranostics







11 Conclusions














Acknowledgments


References









































































































































































J Biomed Opt 14 (2009) 021009











































































































5 Iontophoresis















aluminumndash

garnet (ErYAG mdash

2940 nm) lasers

















































































10 Theranostics







11 Conclusions














Acknowledgments


References









































































































































































J Biomed Opt 14 (2009) 021009











































































































aluminumndash

garnet (ErYAG mdash

2940 nm) lasers

















































































10 Theranostics







11 Conclusions














Acknowledgments


References









































































































































































J Biomed Opt 14 (2009) 021009











































































































































































10 Theranostics







11 Conclusions














Acknowledgments


References









































































































































































J Biomed Opt 14 (2009) 021009











































































































Acknowledgments


References









































































































































































J Biomed Opt 14 (2009) 021009













































































































































































































J Biomed Opt 14 (2009) 021009


































































































03 alibegovic sarah 28 physical energy

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