Applied Che때sπy，

Vol. 13, No. 1, April 2α)9， 29-32

나이팝과 키토산올 이용한 온도감웅성 약물전달 시스탬 효휠 · 허선행 · 남정표 · 김동곤 · 정영일 · 김양배 · 장미경 · 나재훈·

순천대학교 공과대학 나노 · 고분자공학과 (E -mail : jwnah@sunchon.ac.kr.)

Temperature sensitive drug delivery system using PNIP AAM and Chitosan

딘X브뜨」브딘g ' Sun-Heang Heo ' Joung-Pyo Nam' Dong-Gon Kim' Young- !l Jeong . Yang-Bae Kim' Mi-Kyeong Jang ' Jae-woon Nah'

Department of Polymer Science and Engineering, SunchonNationalUniversity, Jeonnam 540-742, Korea

(E -m3il j wn3h@sunchon.3c.kr')

Absrtact

New thermosensitive nanoparticles. based on PNIPAAm- AA core and chitosan shell

structure. were designed and synthesized for the controlled release of the l03ded

drug. PNIPAAm nanoparticle containing carboxylic group on their sur Í3ce was

synthesized using emulsion polymerization. The particle size of synthesized

nanoparticles was varied from 380 nm to 25 nm as temperature of the dispersed

medium increased. LMWSC-conjugated nanoparticles of 2wt% MBA. crosslinking

monomer. leaded to a stable aqueous dispersion at concentration of lmg/l ml

otherwise showed gel collapse temperature. The effect of temperature on the

dynamic behavior of the PNIPAAm chains were 31so studied by dynamic light

scattering and UV - Vis absorption measurements.

Keywords: LMWSC. PNIPAAm. Lower critical solution temperature. Thermosensitive

1. Introduction

A new challenge is the development of the thermosensitive nanogels with biological

activity , especially for drug delivery applications. Several authors have reported the

thermosensitive gel systems based on PNIPAAm conjugated with biomaterials. Kono et

al. synthsized liposomes coated with a copolymers of ~IPAAm and

N ,N-didodecylacrylamide. 1 The release of calcein from the copolymer-modified

liposomes was very slow below LCST, whereas the release was rapid above LCST.

Katayama et al reported the thermosensitive PNIPAAm nanogels conjugating with the

receptor of protein kinase A. 2

Recently our previous studies focused on chemical modifications, nanoparticle

preparation, and drug-release behaviors of low molecular weight water-soluble chitosan

(LMWSC) . In the present study , we have designed novel thermosensitive nanoparticles ,

based on PNIPAAm core exhibiting LCST behaviors and chitosan shell having

biocompatibility , to develop the controlled release of the loaded drug. This study

disclosed the synthesis, characterization and thermosensitive behaviors of nanoparticles

composed of either NIPAAm-co-AA or NIPAAm- co-AA conjugated with chitosan.

29

30

2. Experimental

Materials

정 현·허선행·남정표· 김동곤 ·정영일·김양배·장미경·나재운

Low molecu lar weight water-soluble chitosan (LMWSC) was obtained from KITTOLIFE

Co. Korea. LMWSC was modified to enhance water-solubility as described previously

as a water-sol uble chitosan (\1 W: 10,000, deacetylation degree=97%). ’ :-.J IPAAm was

obtained from Fisher Scientific Inc. (Fair Lawn, NJ , USA) and recrystallized from

hexane. MBA and AA were purchased from Aldrich (Milwaukee, WI , USA) and used

without further purification. Dialysis tubing (MWCO= 12,000) was commercially obtained

from Spectrum.

Preparation 01 NIPAAm-co-AA nanoparticJes

6.80 g of NIPAAm (60mmoI), 0.5 g of SDS (l .7mmoI) , and 0.14 g of MBA (O.91mmoI)

were dissolved in 470 g of double distilled water, degassed with argon. The synthesis

was carried out under argon atmosphere to exclude oxygen. After heating the solution

to 75 oC , 0.5 g of KPS (1.8mmoD and 0.3 g of AA (4.2mmol) in 30 g of water was

added under rigo rous stirring. The reaction became turbid and the reaction proceeded

for 4 h at constant temperature. The obtained NIPAAm-co-AA nanoparticles in

aqueous solution were dialyzed with distilled water by using a dialysis membrane

(celluSep@, molecular weight cut-off= 5,000) for 24 h in order to purify the produc t.

Synthesi능 01 thermosensitive nanoparticJes based on PNIPAAm core and chitosan shell

structure

2 ml of N IPAAm-AA solution 0.2 wt%) was uniformly dispersed in 20ml of

de-miner alized water by ultrasonic for ten minutes. The prepared NIPAAm-AA

solution was slowly added into the st irred LMWSC aqueous solution (1 0 mg in 10 ml

de-mineralized water) and preadsorped for 2 hours at room temperature. After the

preadsorb procedure , 0.5 mg of l-ethyl-3- (3-dimethyl:aminopropy I) ca rbodii mide

(EDAC , Aldrich) , the catalyst of carboxyl-amine conjugation reaction , wa s added to the

solution described above. The nanoparticle- LMWSC conjugation reaction was carried

out for 4 hours with stirring at 25 uc. The resulting LMWSC -conjugated nanoparticle

aqueous solution was dialyzed with distilled water by using a dialy sis

membrane (ce l luSep@’ MWCO= 12,000) for 24 h in order to purify the produc t.

Characterization 01 the thermosensitive nanoparticJes

Thetemperature dependent particlesize of NPAAm-AA and LMWSC conjugate

nanoparticles were measured by the dynamic lights cattering (DLS, Malvern , Zetasizer,

3000HS). T he particle size was measured in 0.1 wt % of nanoparti cles disper

3. Result and disccusion

Preparation 01 NIPAAm-co-acrylic acid nanoparticJes

웅용화학， 제 13 권 제 l 호， zro.:l

나이 팡과 키토산올 이용한 온도감웅성 약불전달 시스템 31

Table 1. Ingredients and Conversions for the synthesis of NIPAAm - AA particles

Sample No. P"l I^^-4(2) PNIAA-4(5) PNIAA-8(5) PNIA^-12(5) Water(g) 500 500 500 500

NIPAAm(g) 6.80(95%) 6.85(91%) 6.75(87%) 6.70(83%) AA(g) 0.3 (4%) 0.3(4%) 0.623(8%) 0.961(12%)

MBA(g) 0.14 (2%) 0.41(5%) 0.4 1(5%) 0.40(5%) SDS(g) 0.5 0.5 0.5 0.5 KPS(g) 0.5 0.5 0.5 0.5

Conversion (%) 98.1 97.8 98.6 98.3

Figure 1. Scanning electron micrograph of

PNIAA -4 (5) nanoparticles

The NIPAAm -co- A^ particl es were

synthesized by emulsion po ly meri zat ion of

NIPAAm monomer in the presence o f \II BA as

a cross-linker , KPS , as an initi ator and SDS

as a surfactan t. The sample number and

detail ingredient of the N IPA^m-AA

nanoparticles were shown in Tabl e 1. Fr om

Table 1, high conversion (>9 5%) o f all

nanoparticles were measured. The scanning

electron micrograph of PNIAA -4 nanoparticle is shown in Figure 1. The electron

micrograph shows the synthesized nanoparticles are spheres.

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T.mpera‘,. (T::) ’.CI. poe’“ e ‘. 티gure 2. Shrinkage beh하iors 01 NIPAAm­AA pcrlicles as a 111lction 01 temperatt.-e

Rgure 3. Eπect 01 M content on the gel­colapse temperature 01 NIPAAm-AA nanoparticles in dou뼈s distilled water

PartjcJe Sjze and the GeJ-coJJapse Temperature of NIPAAm-AA partjcJes

The NIPAAm - AA nanopartles exhibits different thermosensitive behaviors with particle

concentration in water. Figure 2 summarized the results of NIPAAm - AA particles

obtained from dynamic light scattering at various temperature s. Our results did not

show significant difference within the range of 4%-12% acid contents. The particle size

of NIPAAm-AA particle is almost composition independen t.

Figure 2 also showed the significant decrease of particle size as the temperature

increased from 10 oc to 50 oC. Results of transmittance measurement of NIPAAm-AA

Applied Ch앙nist:ry， Vol. 13, No. 1, 200l

정 현·허선행·남정표·김동곤·정영일·김양배·장미경·나재운 32

(1 5 mg of particles / 1 ml 0 f water) as a function of

temperature are shown in Figure 3. In Figure 3, all of the NIPAAm-AA particles show

simila trend o f transmittance: that is , the transmittance of the particle with different AA

content dropped abruptly around 32 "C , which is in consistence

particles at higher concentration

with the particle size

measuremen t.

Thermosensitive behaη，'ors of nanopartic1es based on PNIPAAm core and chitosan sheJJ

structure. As the NIPAA m-AA nanoparticles slowly added into a highly diluted LMWSC Solution,

adsorbed at the surface of the nanoparticles by carboxyl - amine

and the conjugation reaction of NIPAAm- AA particle with LMWSC

by using 3- (3-dimethyl:aminopropy I) carbodiimide <EDAC) . Therefore , it

that t he resulting nanoparticles may have NIPAAm-AA core and cross!inked

chitosan shell structures. Figure 4 shows the size data of PNIAA - LMWSC

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Figure 5 . UV transmitt하lce of PNIPAAm- AA nanoparticles conjugating with chitos하1 at various temperatures.

decreased at below LCST. increased

Figure 4. lñermosensitive behaviors 01 PNIAA -LMWSC nanoparticles.

T __ ‘_(1:)

at around was slze particles The nanoparticles.

LCST light

experiment o f chitosan conjugated nanoparticles were shown in Figure 5.

Figure 5, it is clearly shown that the cloud point of chitosan conjugated P!\J IPAAm-AA

nanoparticles solution was elevated about 2-3 oC compared with pure particles.

transmlsslon

the From

of resu!ts The LCST. above the at r e -decreased and

4. Conclusions

We have re ported the first example of thermosensitive nanoparticles of PNIPAAm-AA

core and chi tosan shell structure for the controlled release of the loaded The

thermosensiti ve characteristics of chitosan conjugated nanoparticles make it potentially

useful in the design of a new type of intelligent drug capsules that is compatible with

cells to relea se its pharmacological activity.

drug.

Takagishi , J Controlled Release,

References

1. K. Kono, A. Henmi ,

59 , 63 (1 999),

2. Y. Katayama, T. Sonoda, M. Maeda, Macromolecules, 34 ,8569 (200 1) .

3. J.W. Nah, M. K. Jang, J Polym Sci Part A: Polym Chem , 40, 3796 (2002)

T. Hayashi , H. H. Yamashita ,

웅용화학，제 13 권 제 1 호， 2009