Bubble-Propelled Jellyfish-like Micromotors for DNA SensingXueqing Zhang, Chengtao Chen, Jie Wu,* and Huangxian Ju

State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University,Nanjing 210023, P. R. China

*S Supporting Information

ABSTRACT: A chemically powered jellyfish-like micromotorwas proposed by using a multimetallic shell and a DNAassembly with catalase decorations modified on the concavesurface to simulate the umbrella-shaped body and the musclefibers on the inner umbrella of jellyfish. Relying on thecatalytic generation of oxygen gas by catalase in H2O2 fuel, thejellyfish-like micromotor showed good bubble-propelledmotion in different biomedia with speed exceeding 209 μms−1 in 1.5% H2O2. The jellyfish-like micromotors could also beapplied for motion detection of DNA based on a displacementhybridization-triggered catalase release. The proposed jelly-fish-like micromotors showed advantages of easy fabrication, good motion ability, sensitive motion detection of DNA, and goodstability and reproducibility, indicating considerable promise for biological application.

KEYWORDS: micromotor, bubble-propulsion, bio-inspiration, DNA assembly, motion detection

1. INTRODUCTIONBy converting chemical,1 biological,2 and external, such asmagnetic,3 optical,4 ultrasonic,5 and electrical,6 energies intomechanical driving energy, a kind of special artificial micro-/nanomaterials, which are defined as micro-/nanomotors, cannavigate autonomously in different environments for diversi-fied applications, including drug transportation,7 biologicalsample analysis,8 targeted therapy,9 invasive surgery,10 environ-mental decontamination,11 and pH sensing.12 The mostdeveloped micro-/nanomotors are prepared in the shapes ofrods/wires,13 tubes,14 spheres,15 and other irregular appear-ances16 with the design of structural asymmetry or asymmetricdistribution of the catalyst. Although these micro-/nanomotorscan be easily prepared by one-pot preparation, layer-by-layerassembly, supramolecular assembly, roll-up fabrication, andtemplate-assisted deposition and growth with controllablemorphology and mass production,17 their motion performance,application environment, and functionalized load are stillchallenged.Many attempts have been made to achieve highly efficient

micro-/nanomotors, among which the biomimetic fabricationis one of the most attractive way.18−20 For example, aphototactic micromotor has been developed based on a JanusTiO2/Si nanotree design in which the TiO2 nanobranchesserve as photoanodes and the Si nanotrunks serve asphotocathodes to release anions and cations, respectively, forpropelling the micromotor by self-electrophoresis.21 Inaddition, inspired by the helical bacterial flagella, helicalmicromotors which can perform the translational corkscrewmotion by magnetic field have been fabricated.22−24 Moreover,a multisegment nanowire has been used to prepare fishlikemagnetically powered nanomotor.25 This nanomotor drives

under a magnetic field in which the mechanical energy is fromthe undulatory motion of the segments of the nanowire. Theartificial biomimetic magnetic micro-/nanomotors can performa precise wireless controllable motion with little influence ofnavigation environment. These studies indicate that thenaturally guided synthesis is highly promising for designingpowerful micro-/nanomotors.DNA is a unique bionanomaterial for constructing func-

tional interfaces and structures because of its highly precise andprogrammable self-assembly property.26 Many elegant exam-ples have revealed that the materials integrated with nucleicacid assembly can possess more physiological functions andcarry on more tasks.27,28 Our previous work has used DNAtechnology to construct the functional layer integrating thesensing and driving units on the intracavity surface ofmicrotubes and fabricated efficient bubble-propelled tubularmicromotors.29 Although these micromotors have madeprogress in biosensing sensitivity by a purposeful DNA design,they still face challenges in the uniform, controllable, andmultifunctional modification, and efficient biorecognition orother biological tasks in the microspace inside microtubes.Jellyfish is a kind of plankton organism and carries a floating

motion in aquatic environment attributing to the specialmuscle fibers on its inner umbrella to discharge the water outof the body through its rapid stretch−contraction. Here,inspired by the jellyfish, a chemically powered micromotor wasproposed. The jellyfish-like micromotor used a multimetallicshell and a DNA assembly with catalase decorations on the

Received: January 10, 2019Accepted: March 19, 2019Published: March 19, 2019

Research Article

www.acsami.orgCite This: ACS Appl. Mater. Interfaces 2019, 11, 13581−13588

© 2019 American Chemical Society 13581 DOI: 10.1021/acsami.9b00605ACS Appl. Mater. Interfaces 2019, 11, 13581−13588

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concave surface of the shell to simulate the umbrella-shapedbody and the muscle fibers on the inner umbrella of thejellyfish, respectively. In contrast to the water jet propulsion ofjellyfish, the proposed micromotor implemented a bubblepropulsion relying on the catalytic generation of oxygen gas bycatalase in hydrogen peroxide solution (Video S1). Theproposed jellyfish-like micromotors showed charming advan-tages: (1) the open inner-shell space made the surfacemodification easier and more effective, resulting in a goodand stable motion at a low concentration of H2O2 fuel; (2)target molecules could be more effectively recognized by theopen sensing surface compared to the inner tubular surface,29

leading to the sensitive motion detection of DNA; (3)benefiting from the biocompatibility and biostability of DNAarchitecture, the micromotors display good motion in differentbiomedia.

2. RESULTS AND DISCUSSION2.1. Fabrication of Jellyfish-like Micromotors. The

preparation of jellyfish-like micromotor is illustrated in Scheme1. Briefly, the multimetallic (Au/Ag/Ni/Au) (from the

outermost to the innermost) shell was prepared by sputteringAu, Ni, Ag, and Au layers sequentially on a SiO2 microspherefollowed by asymmetrical blocking of the convex Au layer with6-mercapto-1-hexanol (MCH) and the dissolution of the silica

template. Then, a sandwich DNA hybridization (DNA1/2/3)was asymmetrically modified on the concave Au surface toconstruct the sensing unit via Au−S binding. Afterward, S1 andS2 hybridized alternately on DNA3 to form long DNAcomplexes for the covalent decoration of catalase, resulting inthe power unit of the micromotor.

2.2. Characterization of the Micromotor. The scanningelectron microscopy (SEM) images indicated the multimetalsdeposited on the SiO2 microspheres uniformly and hemi-spherically (Figure 1a,b). After etching the SiO2 template, amechanically stable hemispherical shell structure with anopening of 20 μm was obtained because of a total thickness of∼300 nm of multimetal layers (Figure 1c). Upon theimmobilization of DNA architecture with catalase decorations,the shell showed an obvious aggregation of the trappedbiomolecules on its concave surface (Figure 1d). The energy-dispersive spectrometry (EDS) analysis of the micromotor(Figure 1e−l) revealed the uniform distribution of theelements Au, Ag, Ni, C, O, P, and Fe. The existence anddistribution of the first three metal elements indicated thepreparation of the multimetallic (Au/Ag/Ni/Au) shell. Addi-tionally, the concentrated distribution of the latter fourelements, which were used to identify the DNA phosphatebackbone and the heme groups of catalase, on the central ringindicated the modification of DNA architecture with catalasedecorations on the concave surface of the multimetallic shell,confirming the successful preparation of the jellyfish-likemicromotor.

2.3. Condition Optimization. The silver-acceleratedcatalytic decomposition of H2O2 was observed for thejellyfish-like micromotors. In contrast to the micromotorsfabricated on Au or Ag monometallic microshells, the Au/Ag/Au multimetallic micromotors exhibited the most vigorousmovement in H2O2 (1.5%) fuel because of the fast productionfrequency of oxygen bubbles (Figure 2 and Video S2). Itshould be pointed out that the phenomenon of silveraccelerating the catalytic decomposition of H2O2 was mainlyaimed at silver alloys.30 Although the metal Ag itself coulddecompose H2O2 to generate O2 bubbles, it was not enough to

Scheme 1. Schematic Fabrication of the Jellyfish-likeMicromotor

Figure 1. SEM images of (a,b) SiO2 microspheres deposited with Au/Ag/Ni/Au, (c) Au/Ag/Ni/Au microshell, and (d) jellyfish-like micromotor.EDS mapping analysis of (e) overlay, (f) Au, (g) Ag, (h) Ni, (i) C, (j) O, (k) P, and (l) Fe of the jellyfish-like micromotor.

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generate motion in H2O2 at low concentration. Thus, this workused Au/Ag/Au alloy microshells to construct jellyfish-likemicromotors.The opening diameter of the microshell affects greatly the

motion behavior of bubble-propelled micromotors.31 Thiswork used Au/Ag/Au-CAT micromotors as substitutes forjellyfish-like micromotors to study the influence of the openingsize of microshells. The motion of Au/Ag/Au-CAT micro-motors at different opening diameters in 1.5% H2O2 wasobserved (Figure 3A). The tracking trajectories showed theAu/Ag/Au-CAT micromotors suffered a decrease in thebubble generation efficiency as well as the numbers of activemicromotors with the decrease of the shell openings (Figure3B and Video S3). This should be because of the decrease ofthe amount of catalase as well as the difficulty in formingbubbles in microshells with small openings. Thus, themicroshells with an opening of 20 μm exhibited the best andthe most stable navigation and were chosen for the fabricationof jellyfish-like micromotors.Furthermore, the effect of the thickness of the interior Ag

layer on the motion speed of the micromotors was examined(Figure 3C and Video S4). The micromotor speed increasedwith increasing the thickness of the Ag layer and reached the

maximum speed at a thickness of 200 nm. The motion speeddecreased with a further increase of the Ag layer thicknessbecause of the weight factor. Hence, the 200 nm Ag layer wasselected for the micromotor preparation.To achieve highly efficient micromotors, the conditions for

the DNA architecture formation and catalase conjugation werealso optimized (Figure 4). According to the motion speed ofthe micromotors, 9 μM DNA1, 20 μM S1 and S2, three layersof S1/S2, and catalase of 2.5 mg mL−1 were chosen for thefabrication of jellyfish-like micromotors. Meanwhile, theconcentration of DNA2 and DNA3 was consistent with thatof DNA1 because they co-construct the sensing unit of themicromotors. Additionally, during DNA1 modification, a high-concentration salt (1 M KH2PO4) was adopted to obtain ahigh conjugation efficiency.

2.4. Motion Property of the Jellyfish-like Micro-motors. Similar with previous reports,32 the jellyfish-likemicromotors exhibited straight, circular, and spiral motions.Here, the micromotors exhibited mainly the straight motion atlow speed and circular and spiral motions at high speedbecause of the degree of balance between the torque producedby oxygen propulsion and the curved structure of themicromotors. However, because of the interior Ni layer in

Figure 2. Time-lapse images of the motion of different microshells (a−c) and micromotors (d−f) during a period of 1.6 s. Scale: 20 μm.

Figure 3. (A) Fabrication procedure of Au/Ag/Au-CAT micromotors. (B) Time-lapse images with autotracking of the motion of Au/Ag/Au-CATmicromotors at sizes of (a) 2, (b) 5, (c) 10, and (d) 20 μm during a period of 2 s. Scale: 20 μm. (C) Effect of the thickness of the interior Ag layeron the motion speed of the micromotors.

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the microshell, the jellyfish-like micromotors could be guidedmagnetically (Video S5).The motion performance of the jellyfish-like micromotors in

H2O2 at different concentrations was observed (Figure 5a).The micromotor speed increased sharply by increasing theH2O2 concentration from 0 to 1.5% and then slowly decreasedin H2O2 with higher concentrations because of their toxiceffect on catalase. The speed of the proposed jellyfish-likemicromotors achieved ∼209 μm s−1 in 1.5% H2O2. This speedwas much higher than that of other Pt-powered Janus33 andmicroshell motors34 because the DNA architecture in thejellyfish-like micromotors provided a biocompatible andmultisite framework for catalase. In addition, the micromotors

also exhibited a good motion speed (∼25 μm s−1) in 0.5%H2O2. The effect of the temperature of the detection solutionon the motion speed was also investigated. The micromotorexhibited the fastest velocity at 37 °C as catalase had the bestactivity at this temperature (Figure 5b).The stability of the micromotors was examined by observing

the motion speeds against different storage times (Figure 5c).The micromotors maintained ∼80% of the speed even after 3weeks, suggesting the good stability of the micromotors. Inaddition, the durability experiment showed the micromotorscould continuously navigate for 3 min in 1.5% H2O2 with aslight sacrifice of the speed (Figure 5d). However, the speed of

Figure 4. Optimization of (a) DNA1 concentration, (b) S1 and S2 concentrations, (c) layers of S1/S2, and (d) catalase concentration.

Figure 5. Effect of (a) H2O2 concentration and (b) detection temperature on motion speed. (c) Stability of the micromotors after storage at 4 °C.(d) Duration of the motion performance in 1.5% H2O2. Normalized speed refers to the ratio of observed velocity to the original speed ofmicromotors.

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the micromotors declined gradually after 3 min because of thedecrease of the enzymatic activity.29

2.5. Assay Performance. The jellyfish-like micromotorsused a sandwich DNA hybridization (DNA1/2/3) which was

Figure 6. (A) Schematic diagram of micromotor-based DNA sensing. (B) Time-lapse images with motion tracking of micromotors for sensing of(a) 0, (b) 0.5, (c) 1, (d) 4, and (e) 8 μM target DNA during a period of 1 s, and (f) relationship of motion speed and the concentration of targetDNA. (C) Average speed of micromotors according to (a) background, (b) 5 μM target DNA, and 50 μM (c) 1 bp mismatch DNA, (d) 3 bpmismatch DNA, and (e) noncomplementary DNA. Scale: 20 μm.

Figure 7. (A) Dependence of motion speeds of the jellyfish-like micromotors and Au/Ag/Pt microshell motors on different biomedia. (B) Time-lapse images of a jellyfish-like micromotor (a−d) and an Au/Ag/Pt microshell motor (e−h) in PBS (a,e), 30 μM BSA (b,f), serum (c,g), and cellculture (d,h), respectively in a period of 1.1 s. Scale: 20 μm.

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modified on the concave Au surface to serve as the sensingunit. The hybridization of target DNA with DNA2 caused therelease of the S1/S2 assembly with catalase decorations fromthe micromotors, resulting in the reduction of the motionspeed (Figure 6A). Under optimal conditions, the relationshipbetween the motion speed of the micromotors and theconcentration of the target DNA was studied (Figure 6B andVideo S6). The speed of the micromotors showed a negativelinear correlation with the concentration of the target DNA inthe range of 25−750 nM and 0.75−10 μM, with the linearequations of S = 206 − 65C and S = 168 − 14C, respectively.The linear correlation of the speed signal directly with thetarget concentration suggested that the jellyfish-like micro-motor-based sensing method was more sensitive than thepreviously reported tubular micromotor-based sensing meth-od.29 The improved sensitivity should be owing to the openstructure of the microshell which was more conducive to targetdiffusion to the sensing unit. Moreover, from the slopes of thelinear equations, the jellyfish-like micromotors showed higherdetection sensitivity at low concentrations of target DNA.Although the detection sensitivity had no advantage over thoseof the electrochemical and fluorescence biosensors,35,36 themicromotor-based DNA assay was more simple, cheap, andfast because the motion speed could be observed directlythrough a microscope without the requirement of a dye/mediator-labeled probe, wash/separation steps, or a lightsource/electrochemical workstation. Furthermore, high detec-tion sensitivity would be achieved with sophisticated DNAdesigns.The specificity of the jellyfish-like micromotor-based DNA

assay for mismatch DNA was observed (Figure 6C and VideoS7). The motion speed of micromotors in response to targetDNA decreased much more than those for 1 bp and 3 bpmismatch DNA even at 10 times higher concentration.Additionally, the presence of the high concentration ofnoncomplementary DNA had a slight effect on the motionspeed of micromotors, indicating the acceptable selectivity todistinguish matched and mismatched DNA.2.6. Motion in Different Biomedia. Figure 7 and Video

S8 showed the motion of jellyfish-like micromotors in differentbiomedia. Comparing with its motion in phosphate-bufferedsaline (PBS) (10 mM, pH 7.2), the speed of jellyfish-likemicromotors in the bovine serum albumin (BSA) solutiondecreased slightly at 1.5% H2O2. Although an obvious decreaseof the speed was observed both in the serum and cell culture,the jellyfish-like micromotors still showed good motion speedover 100 μm s−1. In contrast, the Au/Ag/Pt microshell motors,in which the concave Pt layer served as the power unit todecompose H2O2 and generate bubble-propelled motion,exhibited a worse motion performance in PBS, even containing6% H2O2. Besides, the Au/Ag/Pt microshell motors suffered agreat loss of their motion in protein-rich solutions; indeed,they lost their motion completely in the serum and cell culture.These phenomena suggested: (1) the micromotors using DNAarchitecture with catalase decoration as the power unitexhibited more efficient motion performance than that usingPt layer as the power unit; (2) the proposed jellyfish-likemicromotors could move efficiently in a protein-rich environ-ment and the decrease of motion speed was mainly attributedto the increase of viscosity, rather than to the passivation ofpower unit that occurred in Pt-powered micromotors. Thegood motion performance of the jellyfish-like micromotors in

biomedia at a low concentration of H2O2 guaranteed theirbiosensing application.

3. CONCLUSIONS

This work proposed a jellyfish-like micromotor by constructinga DNA architecture with catalase decorations on the concavesurface of a multimetallic microshell. The micromotor showedgood bubble-propelled motion in a low concentration of H2O2because of the high catalytic ability of the DNA−catalasearchitecture. In addition, benefiting from the high ratio ofcatalase to each sensing unit and the open structure of the shellshape, the micromotor could perform sensitive motiondetection of DNA. The jellyfish-like micromotor also showedgood motion performance in protein-rich biomedia, goodstability, and reproducibility, indicating considerable promisefor biological applications.

4. EXPERIMENTAL SECTION4.1. Materials and Reagents. The deposition materials of Au

(99.99%), Ag (99.99%), and Pt (99.99%) were purchased fromBeijing Zhongjingkeyi Technology Co., Ltd. (China), and Ni(99.995%) was purchased from Zhongnuo Advanced MaterialTechnology Co., Ltd. (Beijing, China). The cell culture and BSAwere from Nanjing KeyGen Biotech. Co., Ltd. (China). Fetal calfserum (10%; Gibco) was purchased from Life Technologies (USA).Catalase from bovine liver, 11-mercaptoundecanoic acid (MUA), andMCH were supplied by Sigma-Aldrich (USA). Sodium cholatehydrate (NaCh) and silicon dioxide microspheres were purchasedfrom Alfa Aesar Chemical Co., Ltd. (China). Other reagents inanalytical grade and ultrapure water were used in the whole work. Thesequences of oligonucleotides from Sangon Biological EngineeringTechnology & Co., Ltd. (Shanghai, China) were as follows (from 5′to 3′):

DNA1: SH−(CH2)6−AAAAAACCATGTTTACCGDNA2: TAACACGGTCTAAGGTGACGGTAAACATG-

GACGTCGDNA3: TAGACCGTGTTA T AGCGGCGATCTGGGGGAGTACS1: COOH-GCCGTGCCAGCACGTCTACCT A GTACTCCCC-

CAGATCGCCGCTS2: COOH-AGGTAGACGTGCTGGCACGGC T AGCGGC-

GATCTGGGGGAGTACTarget DNA: CGACGTCCATGTTTACCGTCACCTTA-

GACCGTGTTA1 bp mismatch DNA:CGACGTCCATGTTTAC G GTCACCTTAGACCGTGTTA3 bp mismatch DNA:CGACGTC G ATGTTTAC G GTCACCTTAGACC C TGTTANoncomplementary DNA:GCGTCGTTGGCCCAGTTAGTTAGGGCTCTATGAGGTThe complementary bases of DNA2 with DNA1 and DNA3, and

DNA3 with S1 and S2 are shown in bold and bold italics,respectively.29

4.2. Fabrication of Au/Ag/Ni/Au Microshell. The fabrication ofthe multimetallic microshell was based on a previous report.31 SiO2microspheres (20 μm) were diluted with ethanol solution underultrasonication and then dropped on a glass slide which waspretreated with Piranha solution to form a self-assembly monolayer;50 nm Au, 20 nm Ni, 200 nm Ag, and 50 nm Au were successivelydeposited onto the silicon monolayer.

After the deposition, the Au/Ag/Ni/Au/SiO2 Janus microsphereswere peeled off into water through ultrasonication. Subsequently theJanus microspheres were redispersed into 1 mM MCH overnight toblock the outer Au layer. Then, the SiO2 template was completelyremoved by 3 M NaOH for 8 h, and the Au/Ag/Ni/Au microshellswith their convex Au surface blocked with MCH were obtained afterwashing with ultrapure water three times.

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Au/Ag/Au microshells were also prepared under the sameprocedure without the deposition of 20 nm Ni. In addition, using2, 5, and 10 μm SiO2 microspheres as templates, Au/Ag/Aumicroshells with the opening diameters of 2, 5, and 10 μm wereprepared. Here, 10 μm Au/Ag/Au microshells were prepared underthe same procedures as that for 20 μm microshells, but for the 2 and 5μm microshells, 25 nm Au, 100 nm Ag, and 25 nm Au weresuccessively deposited onto the silicon monolayer.Additionally, 300 nm Au or Ag was deposited onto the 20 μm SiO2

template monolayer to fabricate Au or Ag monometallic microshells.4.3. Fabrication of Au/Ag/Pt Microshell Motors. 50 nm Pt,

200 nm Ag, and 50 nm Au were sequentially sputtered onto the 20μm SiO2 monolayer, followed by etching the silica template in 3 MNaOH overnight. After washing with DI water, the Au/Ag/Ptmicroshell motors were prepared and stored at 4 °C before use.4.4. Fabrication of Au/Ag/Au-CAT Micromotors. The Au/Ag/

Au microshells were blended with a mixed solution of 5 mM MUAand 0.75 mM MCH for 8 h. Then, the carboxyl groups of MUA wereactivated by N-ethyl-N′-(3-(dimethylamino)propyl)carbodiimide/N-hydroxysuccinimide for the subsequent binding of catalase (2.5 mgmL−1) overnight. After washing, the Au/Ag/Au-CAT micromotorswere obtained and stored at 4 °C before use.4.5. Fabrication of Jellyfish-like Micromotors. First, MCH-

Au/Ag/Ni/Au microshells were incubated with DNA1 (9 μM) whichwas pretreated with tris-(2-carboxyethyl) phosphine hydrochloride(1.35 mM) overnight for asymmetric modification of DNA1 on theconcave Au surface via Au−S binding.29 Then, the microshells wereblocked with MCH along with the orientation of DNA1. Next, themicroshells were successively incubated with DNA2 and DNA3 (9μM), followed by multiple alternative hybridization in S1 and S2 (20μM) to form the functional DNA architecture in the concave Ausurface. Afterward, the microshells were activated to decorate catalaseon S1 and S2, following the same procedure described in Au/Ag/Au-CAT. The obtained jellyfish-like micromotors were stored at 4 °Cbefore use.One thing to be noted is that the Au, Ag, and Au/Ag/Au

micromotors were prepared on Au, Ag, and Au/Ag/Au microshells,respectively, using the same procedures described for the jellyfish-likemicromotors.4.6. Motion Detection of DNA. First of all, the jellyfish-like

micromotors were mixed with various DNA solutions. Then, theywere incubated at 37 °C for 30 min for target recognition and therelease of catalases from the micromotors. After mixing with the fuelsolution, the jellyfish-like micromotors were dropped on the glassslides for observation by an inverted microscope (Leica DMI 3000B).Here, the fuel solution was the mixture of 1.5% H2O2 and 0.8% NaCh.The speed of micromotors was calculated by dividing the trajectoriesby time intervals using Leica MM AF 1.5 software. In this work, thestandard deviation from 10 micromotors was used as the error bar infigures.

■ ASSOCIATED CONTENT*S Supporting InformationThe Supporting Information is available free of charge on theACS Publications website at DOI: 10.1021/acsami.9b00605.

Video S1: Autonomous motion of jellyfish-like micro-motors (prepared with one S1/S2 layer) (AVI)Video S2: Autonomous motion of Au, Ag, and Au/Ag/Au microshells and Au, Ag, and Au/Ag/Au micromotors(AVI)Video S3: Autonomous motion of Au/Ag/Au-CATmicromotors at different sizes (AVI)Video S4: Autonomous motion of Au/Ag/Au-CATmicromotors prepared on Au/Ag/Au alloy microshellwith different thicknesses of the interior Ag layer (AVI)Video S5: Autonomous motion of jellyfish-like micro-motors in response to external magnetic field (AVI)

Video S6: Autonomous motion of jellyfish-like micro-motors in response to target DNA with differentconcentrations (AVI)Video S7: Autonomous motion of the proposed jellyfish-like micromotors in response to different DNA (AVI)Video S8: Autonomous motion of the proposed jellyfish-like micromotors and Au/Ag/Pt microshell motors indifferent biomedia with 1.5 and 6.0% H2O2 fuel,respectively (AVI)

■ AUTHOR INFORMATIONCorresponding Author*E-mail: wujie@nju.edu.cn. Phone/Fax: +86-25-89681923.ORCIDJie Wu: 0000-0003-1379-122XHuangxian Ju: 0000-0002-6741-5302NotesThe authors declare no competing financial interest.

■ ACKNOWLEDGMENTSWe gratefully acknowledge the National Natural ScienceFoundation of China (21575063), and Independent ResearchFoundation from State Key Laboratory of Analytical Chemistryfor Life Science (5431ZZXM1807).

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ACS Applied Materials & Interfaces Research Article

DOI: 10.1021/acsami.9b00605ACS Appl. Mater. Interfaces 2019, 11, 13581−13588

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