Biomimetic Octopus-like Particles for Ultraspecific Capture and

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Biological and Medical Applications of Materials and Interfaces

Biomimetic Octopus-like Particles for Ultraspecific Capture and Detection of Pathogens Dongmei Lv, Huping Jiao, Jianwei Dong, Li Sheng, Jinsong Liu, Haisi Dong, Ang Su, Mingjun Zhang, Zhiping Xia, James T. Oswald, daxin pang, Junqiu Liu, and Hongsheng Ouyang ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.9b05666 • Publication Date (Web): 31 May 2019 Downloaded from http://pubs.acs.org on May 31, 2019

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ACS Applied Materials & Interfaces

Biomimetic Octopus-like Particles for Ultraspecific Capture and Detection of Pathogens Dongmei Lv,†# Huping Jiao,†# Jianwei Dong,†# Li Sheng,‡ Jinsong Liu,† Haisi Dong,† Ang Su,† Mingjun Zhang,† Zhiping Xia,§ James T. Oswald,‖ Daxin Pang,†* Junqiu Liu†* and Hongsheng Ouyang†*

†College of Animal Science, Jilin University, Changchun, 130062, China; State Key

Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, China

‡Petrochemical Research Institute, PetroChina, Beijing, 102206, China

§Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of

Military Veterinary, Changchun 130122, China

ACS Paragon Plus Environment

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‖School of Nanotechnology & Chemical Engineering, University of Waterloo, Waterloo

ON, Canada

Keywords: octopus-like structure, multiarm, multivalent interaction, pathogens, capture and detection

Abstract: Infectious diseases caused by pathogenic bacteria (such as sepsis and meningitis) seriously threaten public health, rapid and accurate identification of target bacteria is urgently needed to prevent and treat bacterial infections. Although technologies including plate-counting and polymerase chain reaction have been established to detect the pathogenic bacteria, they are either time-consuming or sophisticated. Herein, a biomimetic octopus-like structure integrated merits of multiarm and multivalent interaction is designed for ultra-specific capture and detection of pathogens. The flexible polymeric arms and multivalent ligands work together to mimic the arm-sucker coordination of octopus in effectively grasping of targeting pathogens, leading to a remarkably high capacity and specificity for target capture (above 98%, 10


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CFU mL−1) without nonspecific absorption of background pathogens. The captured bacteria can be identified point-of-care by the surface-enhanced Raman spectroscopy (SERS) method with a detection limit of 10 cells mL−1.

1. INTRODUCTION

Infectious diseases caused by pathogenic bacteria seriously threaten public health.1, 2 To prevent and treat bacterial infections effectively, rapid and accurate identification of target bacteria is urgently needed.3, 4 More importantly, purification of the target bacteria from the complicated practical samples is indispensable for further culture to carry out drug sensitivity or virulence tests in treatment and therapy process.5 However, traditional culture-based methods such as plate-counting method or multiple-tube fermentation technique are usually too time-consuming and labor-intensive.6 The high throughput sequencing and microarray can realize multiple bacteria detection simultaneously, but these technologies also require bacterial DNA isolation in advance, complex process for enzyme reaction preparation and expensive equipments for nucleic acid amplification.7


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As alternatives, biosensors have received extensive attention due to their integrated design of recognition, signal transduction and visualized output that enable sensitive sensing of pathogenic bacteria.8,

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However, biosensors usually require signal

amplification, which could lead to false positives, a strategy to enrich and separate the targets directly from the mixture before detecting would benefit for minimal detection background and maximum accuracy. Moreover, biosensors are rarely used for bacterial removal, which would provide prompt treatment to reduce or even eliminate bacterial infections in the case of emergency or preventive treatment.10

Recently, bacterial capture system built based on the synergistic effect of local topographic interactions between the nanostructures and nanoscale extracellular organelles have been reported, most of them employed stiff inorganic nanowires made of Si or NiCo(OH)2CO3,11-13 the common feature of these existing separation techniques is that the stiff materials only introduce point contacts and relatively weak interaction forces,14 hence, increasing the contact area and interactions between bacteria and capture platforms becomes a key point for improving capture efficiency. Enlightened by


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the physiology and predation of octopus, biomimetic well-defined patterns resemble to the octopus’ arm-sucker structure have been designed for adhesion and biomedical applications.15-17 For example, Chen et al. have fabricated octopus-shaped hydrogel to maximize available capture area and improved the cell-capture efficiency.18 Baik et al. found that the artificial architecture similar to the suction cups of octopus exhibit outstanding adhesion ability.19 With these in mind, we hypothesize that the octopus mimic would be a rational design to optimize the bacterial-capture efficiency. However, the realization of design for manufacturability and the elucidation of mechanism for attachment behavior still need continued efforts.

In this work, we develop a facile strategy based on a novel synthetic method to mimic the octopus-like architecture on a large scale to achieve a highly effective and specific capture of bacterial pathogens. The bio-inspired octopus-like beads have multiple polymeric arms and many ligands distribute along each arm playing roles as the octopus’ suckers do. The biomimetic arms with a diameter of about 30 nm and an easily customizable length are very flexible, easy to curl and move around freely, leading to


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more opportunities to contact target pathogens. On the other hand, the ligands modified on each arm provide multivalent binding sites for the bacterial cell surface on a molecular scale, the cooperative multivalent ligand-receptor interactions result in dramatically enhanced binding that let the octopus-like beads successfully capture target bacteria once they have adhered. The synergistic effect of multiarm topography and multivalent interactions significantly increases bacterial attachment and improves the efficiency of bacterial capture, as a result, the octopus-like multivalent scaffold architecture have enormous potential for competitively and effectively capture of target bacteria.

2. EXPERIMENTAL SECTION

2.1. Preparation of octopus-like multiarm structure (MAS). The MAS particles were prepared via a facile method according to the previous work.20 Briefly, 0.40 g of initial magnetic cores were dispersed in 100 mL heptane solution which contained 0.2 wt.-% of nonionic surfactant (Span80) by ultrasonication for a few minutes, until the initial magnetic cores were resuspended uniformly in the solution. Subsequently, BFEE (0.2 wt.-%) was added and dispersed under ultrasound for 3 min, then monomers (DVB, 2.0 wt.-%) were


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added to begin the polymerization. After 20 min, 10 mL ethanol was added to terminate the reaction, finally, the MAS particles were collected by magnetic separation and dried under vacuum.

2.2. Preparation of MAS-Ligands conjugates (MAS-Ls): The as-prepared MAS (10 mg), AIBN (2.5 mg) and thiol-functionalized aptamers (20 OD) were added in a round-bottom flask containing 10 mL DMSO and 2 mL deionized water. The flask was tightly sealed using a rubber septum, and then the solution was shaked well and degassed by nitrogen bubbling for 20 min. Subsequently, the solution was reacted for 48 h at 72 °C to complete conversion. Finally, the expected MAS-Ls was obtained and washed with DMSO and water successively, then the product was resuspended in 1 mL phosphate buffer and stored at 4 oC in refrigerator for further use. For preparation of MAS-PEG, MAS (10 mg), AIBN (2.5 mg) and thiol-functionalized PEG2000 (3 mg) were added in a round-bottom flask containing 10 mL DMSO. The flask was tightly sealed using a rubber septum and the solution was shaked well and degassed with nitrogen for 20 min. The solution was further reacted for 48 h at 72 °C to complete conversion. Finally, the MAS-PEG was


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washed with DMSO and water successively, then resuspended in 1 mL phosphate buffer and stored at 4 oC in refrigerator for further use.

2.3. Capture and separation of bacteria by MAS-Ls. Typically, 1×108 bacterial cells were washed and then diluted to 103 CFU mL-1. 0.1 mL of the diluted (103 CFU mL-1) bacterial cells were re-suspended in 1 mL binding buffer (mixture of PBS (100 mM) and blood or food samples was also utilized during the spiked experiments). The resuspended solution was mixed with varied amount of MAS-Ls at 4 oC for 40 minutes with gentle shaking. After washing away the unbound cells by magnetic separation, bound bacterial cells were collected and resuspended in PBS (10 mM) buffer. The capture efficiency was calculated by plate counting method after growing for 10 hours on agar plates (Capture efficiency (%) = (Number of captured cells / Number of spiked cells) ×100%).

For enrichment assay, 1×108 S. aureus cells were washed and then diluted to 103 CFU mL-1. 0.1 mL of the diluted bacterial cells were added to the beaker containing the appropriate amount of binding buffer so that the volumes of enrichment were 0.5 mL, 1 mL, 5 mL, 10 mL, 20 mL, 50 mL and 100 mL, respectively. Then 0.5 mg MAS-Ls was


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added to each beaker with gentle shaking at 4 oC for 10 hours. After washing away the unbound cells by magnetic separation, bound bacterial cells were collected and resuspended in PBS buffer, then were calculated by plate counting method after growing for 10 hours on agar plates.

2.4. Mixture sample detection. S. aureus with any combination of E. coli, L. mono and

S. flexneri (at desired concentration, 500 μL aliquot) were added into a centrifuge tube and mixed evenly. The mixture was incubated with 0.5 mg mL-1 of MAS-Ls at 4 oC for 40 minutes with gentle shaking. After washing away the unbound cells by magnetic separation, bound bacterial cells were collected and resuspended in binding buffer. The MAS-Ls binding bacteria (MAS-Ls-S. aureus) was stored at 4°C for further SERS characterization, or released and subjected to Gram staining method.

2.5. SERS characterization. 100 μL of prepared AgNPs were pipetted into 100 μL of MAS-Ls-S. aureus and vortexed several seconds to make the mixture evenly mixed. The resulting sample (30 μL) was taken and put on a glass slide with a groove, the Raman spectrum was recorded.


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3. RESULTS AND DISCUSSION

3.1. Synthesis of octopus-like multiarm structure. Generally, magnetic particle is used to emulate the head of an octopus, after encapsulating the ‘head’ with polymeric multiarm shell, ligands are subsequently immobilized on each arm via thiol-ene click reaction, achieving biomimetic octopus-like structure with multiarms and multivalent ligands. The design and preparation process of the octopus-like structure are illustrated in Scheme 1.

Scheme 1. Schematic representation of the synthesis process for MAS-Ls.


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This strategy employs magnetic particles as a separation medium and crosslinked poly(divinylbenzene) (PDVB) shells with customizable arms as a reactive matrix. The terminal-functionalized aptamers decorated on the shell as affinity ligands are not only for specific binding to targets through multivalent interactions, but also make the hydrophobic particles more water dispersible. The synthetic route for PDVB shell and conjugation of ligands is shown in Figure S1. With the help of an external magnetic field, the captured pathogens can be easily separated for further detection or culture. To the best of our knowledge, this is the first demonstration of an octopus-like structure that combined with multiarm and multivalency toward the design of magnetic particles in pathogen research. This unprecedented approach has the advantages of simple operation, extremely short synthesis and reaction time and mild conditions. These factors could facilitate the mass production of highly specific and efficient capture agents for commercial uses in rapid and accurate bacterial testing at the point-of-care test.

For more details about the synthesis of MAS, firstly, magnetic particles were dispersed uniformly in heptane with the assistance of a nonionic surfactant under ultrasound. Note


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that the ratio of surfactant-to-particles should be controlled in a proper range. Secondly, initiator, boron fluoride ethyl ether (BFEE), was added to the mixture under ultrasound. It then took two minutes to stabilize the system, ensuring the immiscible initiator had immobilized on the particles’ surfaces. The concentration of BFEE would be controlled precisely to avoid the creation of single initiator droplets, which may lead to solid homogeneous structure (Figure S2), causing adverse effects on the separation behavior of MAS particles in the magnetic field. Finally, with the addition of heptane-soluble monomer, divinylbenzene (DVB), the color of the reaction system quickly turned dark brown and flocculent as the polymerization progressed. The products could be easily separated with the help of an external magnetic field, followed by structural characterization through electron microscopy.


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Figure 1. (a) SEM and (b) TEM images of the typical MAS particles, synthesized with concentration of 0.2 wt.-% of span-80, 0.2 wt.-% of BFEE, 2.0 wt.-% of DVB, 0.2 g of magnetic particles in 50 mL heptane, polymerized for 20 min; (c) TEM image of the arm of a MAS particle; (d) Schematic illustration of grafting ligands to MAS; (e) Suspension study for MAS (left) and MAS-Ls (middle) in water, and separation of MAS-Ls in an external magnetic field (right).

The successful preparation of MAS was confirmed by SEM (Figure 1a). The observed uniform morphologies suggest a uniform growth of arms from the surface of the cores. In addition, it can be seen that the curly arms lay freely on particles’ surface, indicating the


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arm was quite flexible. Another proof for the successful coating of the functional shell was the lower saturation magnetization of the composite particles compared with the bare ones (Figure S3). The morphology evolution of MAS intermediates was also obtained (Figure S4), suggesting the controllability of the arms’ length. TEM result clearly shows the magnetic core-polymeric shell hybrid structure of the particles (Figure 1b) and we found that the polymer component can be divided into two different ordered structures: a spherical shell with a thickness of about 50 nm and arms (nanofibers) with diameters of 30~50 nm (Figure S4a), suggesting the mechanism is distinct when compared with the classical ‘graft from’ method. Figure 1c shows the porous structure of PDVB nanofibers, which further verified the formation of crosslinked networks during the polymerization.

3.2. Conjugation of ligands. So far, we have demonstrated the strategy of the multiarm shells encapsulating the magnetic particle cores rather than being directly anchored to the surface of the core as described in normal chemical graft or physical adsorption methods. This unique formation mechanism endows outstanding stability between the core and multiarm structure, and the integrated properties including magnetism and high


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surface-to-volume ratio of pliable nanofibers make MAS particles an appropriate material for adsorption and separation applications. Moreover, the crosslinked PDVB nature endowed MAS an outstanding stability when performed further chemical modification. Taking these advantages, we tend to build an efficient platform to realize the capture, enrichment, detection and release of target bacteria based on the novel robust structures. Considering ligand and receptor interactions as an essential part of biological recognitions, a further surface modification was performed to immobilize the polymer substrate with the commercial thiol-functioned aptamers via thiol-ene click chemistry (Figure 1d). The reasons we chose aptamers as the targeting ligands were as following: 1) high affinity to the target, 2) lower cost and good stability and 3) helpful to improve the water dispersibility of MAS particles.21, 22 FT-IR spectrum in Figure S5a shows that there are abundant double bonds existing in the polymer matrix, the characteristic vibration bands of which was observed at 1630 cm-1. After the click reaction, the signal of double bonds had decreased and new ones assigned to the aptamers appeared, suggesting the successful grafting of the probes. Figure 1e shows the suspension studies before and after surface modification, MAS and MAS-Ls microparticles were respectively stirred for


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3 minutes in deionized water. Prior to the aptamer functionalization, the particles accumulated on the water surface and adhered to the wall of the glass vial, suggesting a hydrophobic property. In contrast, the ligand grafted particles exhibited good water dispersibility, demonstrating an appealing gain of hydrophilicity. Furthermore, EDS and XPS analysis were performed to analyze the surface chemical composition of the modified MAS (Figure S5b and S5c), and the results show that the grafted MAS-Ligands (MAS-Ls) display additional elements of sulfur and phosphorus atoms as expected for an aptamer-containing surface. Zeta potential analysis was also performed to prove the attachment of aptamers, the results show that the zeta potential distribution of aptamer and MAS-Ls is in agreement with each other (Figure S6), again demonstrate the success of aptamer attachment. The multiple ligands modified on the arms are similar to the armsucker structure of octopus, capable of targeting and binding to an ensemble of acceptors on the bacterial cell surface (multivalent interactions), orient strengthening the interaction between the multivalent interfaces on the molecular level, leads to better adhesion behavior and capture efficiency.


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3.3. Capture and enrichment of bacteria. The octopus-like structure was then applied to evaluate the bacterial capture capacity against Staphylococcus aureus (S. aureus), a model Gram-positive pathogen that can cause food poisoning and various infectious diseases,23 and its highly specific binding with the chosen ligands has already been verified.24 When the MAS-Ls conjugates were introduced to the targeted cells, the flexible arms on the particles’ surface stretched and contact with the cell, while the ligands on the arms interact with the target through multivalent interactions and held it firmly. As shown in Figure 2a, the MAS-Ls exhibited high bacterial-capture efficiency (up to 98%) in binding buffer calculated by plate-counting technique (Figure S7), the dosage of MAS-Ls was optimized to 0.5 mg mL-1 so that the capture efficiency was optimal (Figure S8). Compared with the capture strategies reported before, the less dosage of MAS-Ls realized higher capture efficiency (Table S1), which resulted from the beneficial effect of the multiarms that provide MAS-Ls more opportunities to contact and interact with bacteria. Keeping both the dosage of MAS-Ls and bacterial concentration constant, we examined the binding specificity of MAS-Ls by replacing S. aureus to other bacteria such as Listeria monocytogenes (L. mono), Escherichia coli (E. coli) and Shigella Flexneri (S.


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flexneri). It can be clearly seen from the plate-counting results (Figure 2b) that the MASLs had no binding affinity toward any control bacteria. The Gram stain method was also performed in mixed bacterial solutions. As expected, the MAS-Ls only captured the S.

aureus cells (blue) and none of E. coli cells (red) was observed by optical microscopy, demonstrating its excellent ability to carry out the reliable capture of targets without an undesired interferential background (Figure 2c and 2d). Additionally, we found that the trapped bacteria can be released from MAS-Ls by simply dispersing the conjugated samples in water, as proved by the staining approach under optical microscopic observation (Figure S9). Note that the above results reflect mainly the performance of MAS-Ls in binding buffer, and it’s well known that the shortcoming associated with magnetic beads is the nonspecific adsorption of various components in practical samples as reported by a few literatures.25, 26 We further tested the capture capacity of MAS-Ls in blood as well as several food samples by spiking S. aureus cells at a concentration of 102 cells mL-1. As depicted in Figure S10, the MAS-Ls showed adaptable bacterial-capture efficiency and specificity for S. aureus in a wide range of complex samples, implying that the octopus-like particles have feasibility and practicability of being used in real samples.


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Figure 2. (a) Capture efficiency of S. aureus, L. mono, E. coli and S. flexneri by MAS-Ls in binding buffer, with bacteria concentration of 102 cells mL-1, MAS-Ls concentration of 0.5 mg mL-1; (b) Traditional plate count method for characterization of the capture specificity: (I) S. aureus, (II) L. mono (III) E. coli and (IV) S. flexneri; Gram staining method for (c) mixed samples of S. aureus (103 cells mL-1) and E. coli (103 cells mL-1) and (d) the captured S. aureus from the mixed samples by MAS-Ls.


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Figure 3a shows SEM image of MAS-Ls-S. aureus complexes and demonstrates that

S. aureus is indeed trapped by the functional multiarm structures. The stretched form of the arms which bind to the bacterial surface grasp the target bacteria firmly like the tentacles of octopus (Figure 3b). Each MAS-Ls provides enough space for trapping a certain amount of bacteria due to the multiarm structure of the shell, which account for the splendid capture capacity. Apparently, the arm length plays a key role in the capturing process. As shown in Figure S4f, when the arm is short (less than 300 nm), the specific area is lower and decrease the contact chance between MAS-Ls and S. aureus, which consequently lower the capture capacity by roughly 20%. However, when increased the arm length to a certain degree (more than 1 μm), the arms tend to intertwist together, resulting in poor dispersibility and decrease the capture capacity slightly. On the other hand, the amount of attached aptamers would directly affect the strength of multivalent interaction, and therefore affects the efficiency. As shown in Figure S11, when the grafting degree was decreased from 18.10 to 10.99 μg per milligram MAS, the capture efficiency was down to 75% correspondingly. PEG modified MAS (MAS-PEG) without aptamers was also applied to test the specificity of ligands to S. aureus. As expected, few S. aureus


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were captured by the MAS-PEG particles, suggesting the key role of the ligands in highly specific capture.

Based on above discussion, the specific capturing mechanism of MAS-Ls is illustrated in Figure 3c. In the bacterial suspension, the stretched ultra-thin arms with high specific surface area provide MAS-Ls more opportunities to contact with all kinds of bacteria. The non-target bacteria were repelled due to steric hindrance27-29 while the target one was trapped owing to the strong multivalent interaction between aptamers and bacteria. When the arms attach the bacteria, they can bend to fit the curved surface of targets for more contact regions and adhere the bacteria firmly. The MAS-Ls-S. aureus complexes can be easily isolated from the suspension using a permanent magnet. These promising results prompted us to perform enrichment assays. Keeping the total number unchanged, 102 cells of S. aureus were diluted in different volumes (0.5~100 mL) to achieve various concentrations and then enriched by 0.5 mg MAS-Ls, the result shows that the MAS-Ls can capture 102 cells in 20 mL volume with high bacterial-capture efficiency (above 95%) as shown in Figure 3d, and the efficiency would be higher with increased amount of MAS-


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Ls. According to this, the unique functional multiarm structure makes the MAS-Ls possible to detect trace pathogens with high sensitivity, which can be used in rapid bacterial detection techniques involving enrichment step before detection.

Figure 3. SEM images of (a) MAS-Ls-S. aureus and (b) the local enlarged images of interaction between the arms and bacteria cell, the pseudocolored cell in image (a) to visualize the topographic interaction between the captured cell and MAS-Ls; (c) Schemetic illustration for specific capture of S. aureus by MAS-Ls; (d) Enrichment of 102

S. aureus cells by 0.5 mg MAS-Ls in varied volumes; (e) SERS detection of target bacteria after capture and separation: SERS spectrum of MAS-Ls binding with S. aureus, L. mono,


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E. coli, S. flexneri and blank samples, respectively, with bacteria concentration of 107 CFU mL-1.

3.4. Identification of S. aureus by Surface-enhanced Raman spectroscopy (SERS). To meet the requirement of real-time detection in a practical application, the trapped bacterial cells can be rapidly identified by SERS, a molecular vibration spectroscopy technique that can provide greatly enhanced information about the structural characteristics of a molecule with the help of heavy metal nanomaterials, which make SERS techniques have potential applications in trace detection and quantitative analysis.30,

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Specifically, the

isolated MAS-Ls-S. aureus complexes were first purified and re-dispersed in water, then mixed with prepared Ag nanoparticles (Ag NPs) (Figure S12). The SERS spectra of resultant mixture are shown in Figure 3e. Several emission peaks at 735cm-1, 1337cm-1 and 1458 cm-1 can be seen in the S. aureus captured Raman spectra, especially the peaks at 735 cm-1 increased significantly.32 The same strategy was used for the negative samples, the results show there is no enhanced Raman spectra, indicating the Raman signal is affected only by the target bacteria. A series of dilutions of S. aureus were used


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to measure binding with MAS-Ls and provide the bacteria with a few gradient samples, the S. aureus suspension was further serially diluted to 10 cells per milliliter, the MAS-Ls-

S. aureus and Ag NPs were mixed and further analyzed by SERS to determine whether it contained bacteria or not. The Raman spectra of these samples show that the SERS spectra decrease along with the decreasing of the S. aureus amount (Figure 4a), the linear regression was made between the peak intensity of 735 cm-1 and the S. aureus concentration, and the linear equation was Y=2776*X+470 (R2=0.94) (Figure 4b). Specifically, when the S. aureus concentration was 10 CFU mL-1, the peak at 735 cm-1 could also be distinguished, demonstrating this system is highly sensitive that can detect as few as 10 bacterial cells per milliliter without centrifugation or filtration. By employing the SERS mapping technology, even single-cell detection is expected to be realized (Figure 4c and 4d).33, 34 Thus, the MAS-Ls coupled with SERS method can serve as a perfect candidate for trace pathogen analysis due to its usability, sensitivity and economy.


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Figure 4. (a) SERS detection of target bacteria after capture and separation: SERS spectra take from samples with various S. aureus concentrations (107, 106, 105, 104, 103, 102, 10 CFU mL-1), after being captured by 0.5 mg MAS-Ls; (b) Calibration curve of SERS spectra of MAS-Ls-S. aureus at 735 cm-1 with samples obtained from (a); SERS mapping


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images: (c) Single cell detected by MAS-Ls-S. aureus SERS mapping and its bright field counterpart; (d) SERS mapping of MAS-Ls and its bright field counterpart.

4. CONCLUSIONS

In conclusion, we developed a facile strategy to mimic the arm-sucker coordination of octopus in grasping, fabricated highly specific and efficient bacterial capture agents based on ligands functionalized hierarchical 3D multiarm particles. The flexible arms and multivalent ligands together enhance the interactions between the MAS-Ls conjugates and target bacteria, enables the MAS-Ls highly specific and efficient capture of bacterial pathogens. Taken S. aureus as an example, MAS-Ls could capture targeting bacteria with high efficiency (above 98%) at low concentration (10 CFU mL-1) without obviously nonspecific absorption of background pathogens. The captured bacteria can achieve point-of-care test followed by convenient magnetic separation and real-time SERS identification, as well as can be released or cultured for further analysis. Interference experiments have also been conducted and the results demonstrate that the octopus-like particles have the ability for handling real samples. This strategy is believed suitable for


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many other bioanalytical techniques which involved enrichment step towards microorganism, protein, nucleic acid or cell. In the future, the proposed bioassay is expected to have important applications in clinic diagnosis and treatment.

ASSOCIATED CONTENT

Supporting Information

The Supporting Information is available free of charge on the ACS Publications website. Materials and chemicals, characterization of MAS-Ls, detailed experiments and figures (PDF).

AUTHOR INFORMATION

Corresponding Author [email protected]; [email protected]; [email protected]

Author Contributions D. M. Lv and H. P. Jiao conceived the experiments and wrote the manuscript. D. X. Pang, J. Q. Liu and H. S. Ouyang supervised the project. J. W. Dong, J. S. Liu, H. S. Dong and


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A. Su carried out the experiments. L. Sheng, M. J. Zhang, Z. P. Xia and J. T. Oswald provided support for characterization and analysis. All authors have given approval to the final version of the manuscript. #These authors contributed equally.

Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT

This work was supported by the Program for JLU Science and Technology Innovative Research Team (2017TD-28), the Keypoint Research and Invention Program (AWS17J016) and Open Project of State Key Laboratory of Supramolecular Structure and Materials (sklssm201721).

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Biomimetic Octopus-like Particles for Ultraspecific Capture and

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