Polystyrene Microparticles Research Articles

Production of Polystyrene Microparticles Using Nonisothermal Polymerization in Supercritical Carbon Dioxide

The process of obtaining and micronization of polymeric materials using an original method of nonisothermal polymerization in the medium of supercritical fluid is investigated. Polystyrene microparticles and fibers are synthesized. The influence of the conditions of the microdispersion process on the morphology of the isolated product is evaluated.

Acoustic manipulation of microparticle in a cylindrical tube for 3D printing

Purpose The capability of microparticle/objects patterning in the three-dimensional (3D) printing structure could improve its performance and functionalities. This paper aims to propose and evaluate a novel acoustic manipulation approach. Design/methodology/approach A novel method to accumulate the microparticles in the cylindrical tube during the 3D printing process is proposed by acoustically exciting the structural vibration of the cylindrical tube at a specific frequency, and subsequently, focusing the 50-μm polystyrene microparticles at the produced pressure node toward the center of the tube by the acoustic radiation force. To realize this solution, a piezoceramic plate was glued to the outside wall of a cylindrical glass tube with a tapered nozzle. The accumulation of microparticles in the tube and printing structure was monitored microscopically and the accumulation time and width were quantitatively evaluated. Furthermore, the application of such technology was also evaluated in the L929 and PC-12 cells suspended in the sodium alginate and gelatin methacryloyl. Findings The measured location of pressure and the excitation frequency of the cylindrical glass tube (172 kHz) agreed quite well with our numerical simulation (168 kHz). Acoustic excitation could effectively and consistently accumulate the microparticles. It is found that the accumulation time and width of microparticles in the tube increase with the concentration of sodium alginate and microparticles in the ink. As a result, the microparticles are concentrated mostly in the central part of the printing structure. In comparison to the conventional printing strategy, acoustic excitation could significantly reduce the width of accumulated microparticles in the printing structure (p < 0.05). In addition, the possibility of high harmonics (385 and 657 kHz) was also explored. L929 and PC-12 cells suspended in the hydrogel can also be accumulated successfully. Originality/value This paper proves that the proposed acoustic approach is able to increase the accuracy of printing capability at a low cost, easy configuration and low power output.

Model-Based Performance Study of Dielectrophoretic Flow Separator

This article presents model-based analysis of a dielectrophoretic microfluidic flow separator in terms of separation efficiency and purity. The device employs interdigitated transducer electrodes on the bottom surface, and they run over the entire width of the microchannel. The device realizes type-based separation, specifically electrical properties, by capturing one type of microscale entity on the electrode surface due to positive dielectrophoresis (DEP) while keeping the other type suspended in the medium due to negative DEP. The model describes the trajectory of microscale entities, electric field potential, and fluid velocity in the microchannel and accounts for forces related to DEP, sedimentation, drag, virtual mass, and inertia. The model is used for parametric study using polystyrene and silica microparticles with radius of 3 μ m; parameters analyzed are flowrate, applied electric potential, number of electrode pairs, and electrode/gap length. Separation efficiency of the levitated microscale entity is 100% for all input parameters, while that of the captured microscale entity varies. Separation purity of the captured microscale entity is 100% for all input parameters, as long as the other type remains levitated, while that of the levitated microscale entity varies. The model developed in this article can help select parameters for achieving the desired level of performance metrics. The model is validated using experimental data on levitation of latex microparticles for voltages of 1–8 Vpp in a microfluidic device with electrode/gap length of 20 μ m and height of 120 μ m. The novelty of the model is that it is dynamic and can model the simultaneous capture and levitation of microscale entities in the microfluidic device.

Acoustic dipole and monopole effects in solid particle interaction dynamics during acoustophoresis.

A method is presented for measurements of secondary acoustic radiation forces acting on solid particles in a plain ultrasonic standing wave. The method allows for measurements of acoustic interaction forces between particles located in arbitrary positions such as in between a pressure node and a pressure antinode. By utilizing a model that considers both density- and compressibility-dependent effects, the observed particle-particle interaction dynamics can be well understood. Two differently sized polystyrene micro-particles (4.8 and 25 μm, respectively) were used in order to achieve pronounced interaction effects. The particulate was subjected to a 2-MHz ultrasonic standing wave in a microfluidic channel, such as commonly used for acoustophoresis. Observation of deflections in the particle pathways shows that the particle interaction force is not negligible under this circumstance and has to be considered in accurate particle manipulation applications. The effect is primarily pronounced when the distance between two particles is small, the sizes of the particles are different, and the acoustic properties of the particles are different relative to the media. As predicted by theory, the authors also observe that the interaction forces are affected by the angle between the inter-particle centerline and the axis of the standing wave propagation direction.

Micro/nano particle-based oxygen sensing film for monitoring respiration of cells cultured in a microfluidic device

Oxygen molecules are essential for producing energy in living organisms, meaning that oxygen measurement is required not only in the medical field, but also in research experiments. Porphyrin dyes in polystyrene microparticles were loaded and embedded in dimethylpolysiloxane to create oxygen sensing film. The lifetime of phosphorescence emitted from the film by laser excitation varied depending on the oxygen concentration, and the oxygen partial pressure was quantified from the lifetime. We revealed that the smaller the microparticle size and film thickness, the shorter the response time to the change in oxygen concentration. Next, the film was placed in cell culture microfluidic devices that can form oxygen gradients in the culture layer, and changes of the gradients due to oxygen metabolism of cells and implanted tumor tissues on the sensing film. From this, we demonstrated the effectiveness of the developed oxygen sensing film for medical and biological applications.

Fluorometric determination of ciprofloxacin using molecularly imprinted polymer and polystyrene microparticles doped with europium(III)(DBM)3phen.

The authors describe a microparticle-based system for the detection of the fluoroquinolone antibiotic ciprofloxacin. The method is using the tris(dibenzoylmethane)(1,10-phenanthroline)europium(III) luminophore in polystyrene microparticles along with a molecularly imprinted polymer (MIP) for ciprofloxacin. If ciprofloxacin is captured by the MIP, it quenches the fluorescence of the luminophores. Fluorescence drops linearly in the 0.5-100μgL-1 ciprofloxacin concentration range, and the detection limit is 92ngL-1. The method was applied to the analysis of fish samples to assess the analytical performance of the probe. Recoveries ranged from 85.4 to 86.6%, and relative standard deviations between 2.1 and 3.9% (for n = 5). Graphical abstract Schematic presentation of a microparticle-based probe using the tris(dibenzoylmethane)(1,10-phenanthroline)europium(III) luminophore in polystyrene particles along with a molecularly imprinted polymer for ciprofloxacin. After removal of template, carboxylic groups left in the probe can bind to ciprofloxacin through hydrogen bonds.

Evaporative deposition of mono- and bi-dispersed colloids on a polydimethylsiloxane (PDMS) surface

Evaporative deposition of mono- and bi-dispersed colloids on a polydimethylsiloxane (PDMS) surface was studied. At particle concentrations of 0.02 and 0.08 wt%, 1.58 μm diameter polystyrene (PS) microparticles were uniformly distributed from mono-dispersed colloids. PS microparticles located at the edge of the deposition increased when the particle concentration increased to 0.32 and 1.28 wt%. Mono-dispersed colloids of 1.21 μm silica microparticles produced a ring-like deposition at particle concentrations ranging from 0.02 to 0.32 wt%. The width of the ring increased with increasing concentration and a mountain-like structure was produced at 1.28 wt%. The settling speed of 1.21 μm silica microparticles is 14 times greater than 1.58 μm PS microparticles resulting in easier settling of silica compared with PS microparticles. Experimental investigations show PS microparticles are dragged inward with the depinning contact line, and the outmost silica microparticles are pinned. The edge of the depositions of bi-dispersed colloids were made up of smaller microparticles and larger microparticles were found far from the edge due to capillary force.

Mie scattering and microparticle-based characterization of heavy metal ions and classification by statistical inference methods.

A straightforward method for classifying heavy metal ions in water is proposed using statistical classification and clustering techniques from non-specific microparticle scattering data. A set of carboxylated polystyrene microparticles of sizes 0.91, 0.75 and 0.40 µm was mixed with the solutions of nine heavy metal ions and two control cations, and scattering measurements were collected at two angles optimized for scattering from non-aggregated and aggregated particles. Classification of these observations was conducted and compared among several machine learning techniques, including linear discriminant analysis, support vector machine analysis, K-means clustering and K-medians clustering. This study found the highest classification accuracy using the linear discriminant and support vector machine analysis, each reporting high classification rates for heavy metal ions with respect to the model. This may be attributed to moderate correlation between detection angle and particle size. These classification models provide reasonable discrimination between most ion species, with the highest distinction seen for Pb(II), Cd(II), Ni(II) and Co(II), followed by Fe(II) and Fe(III), potentially due to its known sorption with carboxyl groups. The support vector machine analysis was also applied to three different mixture solutions representing leaching from pipes and mine tailings, and showed good correlation with single-species data, specifically with Pb(II) and Ni(II). With more expansive training data and further processing, this method shows promise for low-cost and portable heavy metal identification and sensing.

Multi-Scale Study of Branched Electrodeposits

This study concerns the growth of metallic ramified branches formed by galvanostatic electrolysis of a stagnant metal salt aqueous solution inside a horizontal Hele-Shaw (thin gap) cell. Indeed, without supporting electrolyte, the electroneutrality constraint forces the deposit to grow rapidly in the form of long ramified branches made up of crystals whose size might be as lower than 100 nm [1-2] . The presentation focuses on the study of these branches growth, the understanding and the elucidation of the formation mechanisms of its nanostructure (crystals assembly) in order to exploit it as an alternative process for nanoparticles synthesis [2]. Besides, we propose here a new experimental protocol allowing to recover the whole electrodeposit assembly without damages, in order to process to its multiscale characterization and also the determination of the local microscopic morphology in each location of one branch. This presentation focuses specifically on the growth of the branches of copper, silver and iron at i) the macroscale for the branch pattern (10 µm to 1 mm, direct optical visualizations) and ii) also the scale of the nanocrystals (from 50 up to 500 nm, Scanning Electron Microscopy SEM). For each experiment, the branch pattern and structure are collected, and the measurements enabling correlating the impact of large scale transport phenomena on the resulting micro/nano-structure. The data are analysed with the support of theoretical models at both macro and micro scales. The effects of the current density J (16-266 mA/cm2), the electrolyte concentration C (0.1-0.5M), the type of metal (copper, silver, iron) and the cell thickness (25-100 µm) are investigated. At the macroscale, the experimental results are compared to the prediction of a specifically developed growth model based on a “2D dielectric breakdown” [4] scheme assuming a diffusion-limited process for the metallic cation (Mλ +) and taking into account a finite growth velocity vg for the electrodeposit. For low J/C, the experimental and theoretical patterns (see the figure) are fractal up to a cut-off length, corresponding to the diffusion length Ld = D/vg (D: diffusion coefficient). However, there are some differences between the theoretical and experimental apparent density of the deposit as well as in Sand time (time for the full depletion of the cations at the electrode marking the onset of the branch growth). These differences are related to non-diffusive mass flux generated by concentration gradients (natural convection) and the electric field (electroconvection) [5]. The resulting fluid flows have been observed by tracking the motion of polystyrene microparticles (15 µm) into the cell. Exacerbation of each one has been observed varying the cell depth (natural convection) and C (electroconvection). The obtained fluid velocity scales are used to discuss the effect of each of the non-diffusive flux on the branch pattern. At the microscale, the operating parameters affect both the size and the form of the crystals constituting the branches: two distinctive electrocrystallisation growth regimes of the deposit were distinguished, thanks to the SEM observations: one leading to the formation of non-dendritic crystals with well-developed facets and the other giving dendritic crystals (as shown in the figure). Indeed, for all precursors involved (Cu2+, Ag+ and Fe2+) at constant concentration for the deposition under high J, the branches are composed of dendrites, on which small non-dendritic crystals have nucleated and grown. The amount and the size of these non-dendritic crystals decrease when J increases. For Cu and Ag, and for the lower J values investigated, no dendritic structures are observed; the branches are only constituted by piles of non-dendritic crystals with rather wide sizes distribution. Dendrites are always observed in the case of Fe. Using the Fleury’s nucleation model [1] and considering the instability of Mullins Sekerka [6] adapted to the electrochemical case (providing a threshold for the onset of the growth instability, related to the onset of dendrite growth here), it is proposed that these microstructure differences are due to a competition between nucleation and out of equilibrium crystalline growth. This size distribution also differs according to the metal. This is related to their specific surface energies. [1] V. Fleury, Nature, vol. 390, no 6656, p. 145-148,Nov. 1997. [2] A. Iranzo and al, Electrochimica Acta, vol. 250, p. 348-358, Oct. 2017. [3 L. Niemeyer and al, Phys. Rev. Lett., vol. 52, no 12, p. 1033-1036, Mar 1984. [4] J. M. Huth, and al, Phys. Rev. E, vol. 51, no 4, p. 3444-3458, Apr. 1995. [5] W. W. Mullins et R. F. Sekerka, J. Appl. Phys., vol. 34, no 2, p. 323-329, Feb. 1963. Figure 1

Cell Internalization in Fluidic Culture Conditions Is Improved When Microparticles Are Specifically Targeted to the Human Epidermal Growth Factor Receptor 2 (HER2).

Purpose: To determine if the specific targeting of microparticles improves their internalization by cells under fluidic conditions. Methods: Two isogenic breast epithelial cell lines, one overexpressing the Human Epidermal Growth Factor Receptor 2 (HER2) oncogene (D492HER2) and highly tumorigenic and the other expressing HER2 at much lower levels and non-tumorigenic (D492), were cultured in the presence of polystyrene microparticles of 1 µm in diameter, biofunctionalized with either a specific anti-HER2 antibody or a non-specific secondary antibody. Mono- and cocultures of both cell lines in static and fluidic conditions were performed, and the cells with internalized microparticles were scored. Results: Globally, the D492 cell line showed a higher endocytic capacity than the D492HER2 cell line. Microparticles that were functionalized with the anti-HER2 antibody were internalized by a higher percentage of cells than microparticles functionalized with the non-specific secondary antibody. Although internalization was reduced in fluidic culture conditions in comparison with static conditions, the increase in the internalization of microparticles biofunctionalized with the anti-HER2 antibody was higher for the cell line overexpressing HER2. Conclusion: The biofunctionalization of microparticles with a specific targeting molecule remarkably increases their internalization by cells in fluidic culture conditions (simulating the blood stream). This result emphasizes the importance of targeting for future in vivo delivery of drugs and bioactive molecules through microparticles.

Efficient Low Shear Flow-based Trapping of Biological Entities

Capturing cells or biological entities is an important and challenging step toward in-vitro studies of cells under a precisely controlled microscale environment. In this work, we have developed a compact and efficient microdevice for on-chip trapping of micro-sized particles. This hydrodynamics-based trapping system allows the isolation of polystyrene micro-particles with a shorter time while inducing a less hydrodynamic deformation and stress on the particles or cells both after and before trapping. A numerical simulation was carried out to design a hydrodynamic trapping mechanism and optimize the geometric and fluidic parameters affecting the trapping efficiency of the microfluidic network. By using the finite element analysis, the velocity field, pressure field, and hydrodynamic force on the micro particles were studied. Finally, a PDMS microfluidic device was fabricated to test the device’s ability to trap polystyrene microspheres. Computational fluid analysis and experimental testing showed a high trapping efficiency that is more than 90%. This microdevice can be used for single cell studies including their biological, physical and chemical characterization.

Impact dynamics of a polystyrene suspension droplet on nonwetting surfaces measured using a quartz crystal microresonator and a high-speed camera

We investigated the impact dynamics of droplets containing various sizes and concentrations of polystyrene microparticles (PSM) on superhydrophobic surfaces using a high-speed camera and a quartz crystal microresonator (QCM). Gold nanoflake structures were synthesized on QCM surfaces and treated with perfluorooctane ethylthiol molecules to obtain superhydrophobic characteristics. Upon the collision onto the superhydrophobic surface, the droplet spread, retracted, and bounced off the surface due to its nonwetting characteristics. Within the experimental range of PSM size and PSM concentration, the high-speed camera detected only negligible changes in the impact dynamics; however, abnormally large changes in the resonance frequency were observed with the QCM when the concentration or sizes of the PSM exceeded a certain threshold. The abnormal change in frequency was attributed to the formation of a shear-induced PSM structure.

Simultaneous acoustic and photoacoustic microfluidic flow cytometry for label-free analysis

We developed a label-free microfluidic acoustic flow cytometer (AFC) based on interleaved detection of ultrasound backscatter and photoacoustic waves from individual cells and particles flowing through a microfluidic channel. The AFC uses ultra-high frequency ultrasound, which has a center frequency of 375 MHz, corresponding to a wavelength of 4 μm, and a nanosecondpulsed laser, to detect individual cells. We validate the AFC by using it to count different color polystyrene microparticles and comparing the results to data from fluorescence-activated cell sorting (FACS). We also identify and count red and white blood cells in a blood sample using the AFC, and observe an excellent agreement with results obtained from FACS. This new label-free, non-destructive technique enables rapid and multi-parametric studies of individual cells of a large heterogeneous population using parameters such as ultrasound backscatter, optical absorption, and physical properties, for cell counting and sizing in biomedical and diagnostics applications.

Multi-level separation of particles using acoustic radiation force and hydraulic force in a microfluidic chip

Combined with acoustic separation and hydraulic separation technology, a microfluidic chip, which can achieve multi-level particle separation, is proposed in this work. The chip uses the sheath flow on both sides to align the mixed particles in the set area (near the side of the channel) of the separation channel. And then, the mixed particles successively pass through the acoustic surface wave and hydraulic action area, which are generated by modulating interdigital transducers and adjusting the flow ratio, respectively, and finally realize multiple particle separation under the acoustic radiation and hydraulic force. The corresponding separation experiments were carried out using polystyrene (PS) microparticles with diameters of 1 µm, 5 µm, and 10 µm, respectively. Moreover, we explored the influence of the peak-to-peak voltage (Vpp) and flow ratio on the PS microparticles separation effect, and the separation effect is optimal at the flowrate in the main channel is 4 mm/s, Vpp = 25 V, A1 = 0.2, A2 = 0.5. Under these conditions, the separation purity of 1 µm, 5 µm, and 10 µm PS microparticles are 95.60%, 91.67%, 93.75%, respectively, and their separation rates are 96.67%, 89.19%, and 96.77%, respectively. The combined multi-level separation chip has the advantages of simple structure, high separation accuracy, high separation efficiency, and the ability to sort multiple particles, which can be applied to chemical analysis, cell sorting, biomedicine.

An innovative "unlocked mechanism" by a double key avenue for one-pot detection of microRNA-21 and microRNA-141.

The accurate and quantitative detection of microRNAs (miRNAs) as next-generation, reliable biomarkers will provide vital information for cancer research and treatment. However, their unique, intrinsic features pose quite a challenge for miRNA profiling, especially for multiplexed detection. Thus, there is a strong and an ever-growing need to develop an accurate, simple, sensitive and specific miRNA sensing method.Methods: In this study, a simple and novel sensor is presented that uses a flow cytometry (FCM) method based on the double key “unlocked mechanism” and a fluorescence enrichment signal amplification strategy. The “unlocked mechanism” was cleverly designed via using hairpin DNA probes (HDs) labeled by fluorescent particles (FS) as the lock to block part of them, which can specifically hybridize with the probe on polystyrene microparticles (PS). The target miRNA and duplex-specific nuclease (DSN) forming the double key can specifically open the HDs and cleave a single-stranded DNA (ssDNA) into DNA/RNA dimers circularly in order to unlock the special part of the HDs to be specially enriched further on the PS.Results: The designed sensor with a hairpin structure and DSN special performance was found to have a high specificity. The circularly unlocking fluorescent probes and fluorescent signal enrichment can be beneficial for achieving a high sensitivity with a detection limit of 3.39 fM for miRNA-21. Meanwhile, the performance of multiplexing was estimated by simultaneous detection of miR-21 and miR-141, and the method also allowed for miR-21 detection in breast cancer blood samples.Conclusion: The designed sensor based on an “unlocked mechanism” and a signal enrichment strategy resulted in a one-pot, highly specific and sensitive detection of multiplex miRNAs. The whole detection without the need for a complex purification process is based on a FCM and is expected to have a great value in cancer diagnosis and biomedical research.

Measurement of the magnetic susceptibility of subtle paramagnetic solutions using the diamagnetic repulsion of polymer microparticles.

Herein, we described a microfluidic device that enabled the measurement of magnetic susceptibility of a subtle paramagnetic solution that could not be determined by conventional magnetic susceptibility measurement methods such as a superconducting quantum interference device (SQUID). We measured the diamagnetic repelling velocity of polystyrene microparticles suspended in a weak paramagnetic solution including 50-150 mM of gadolinium-diethylenetriamine penta-acetic acid (GD-DTPA) and superparamagnetic iron oxide nanoparticles (SPION) (10 nm in diameter) dispersed in distilled water at various concentrations. The measured diamagnetic repelling velocities correlated with our prediction and also with the magnetic susceptibility of the SPION solution measured by a SQUID magnetometer. Via this approach, we could determine the magnetic susceptibility of the subtle paramagnetic solution of GD-DTPA that could not be measured via the conventional method. This study provides us with the new capability of analyzing weakly paramagnetic solutions such as paramagnetic components or metal contaminants present in environmental liquid samples at low concentrations.

Simulated digestion of polystyrene foam enhances desorption of diethylhexyl phthalate (DEHP) and In vitro estrogenic activity in a size-dependent manner

Marine polychaetes and fish are known to ingest polystyrene microparticles in the environment. Laboratory microplastic feeding experiments have demonstrated that plastic may release endocrine-disrupting compounds such as diethylhexyl phthalate (DEHP), which can cause adverse effects in both vertebrates and invertebrates. In order to determine the influence of size and digestive conditions on the desorption of DEHP and other plasticizers to polychaetes and fish, we exposed polystyrene particles of various sizes under invertebrate and vertebrate digestive conditions (vertebrate mimic; pepsin, pH = 2.0, 24 °C, invertebrate mimic; Na taurocholate pH = 7, 18 °C). Estrogen receptor activation and concentrations of 12 plasticizers were measured in the extracts. DEHP, bisphenol S and 4-tert-octylphenol were the only compounds detected. Simulated vertebrate gut digestion did not significantly enhance the release of chemicals nor estrogenic activity. However, a 6.3 ± 2.0-fold increase in the concentration of DEHP was observed in extracts from invertebrate gut conditions (Mean ± SD; N = 24, p < 0.0001). Additionally, estimated particle surface area was positively correlated with estrogenic activity across all treatment types (r = 0.85, p < 0.0001). Overall, these data indicate an elevated bioaccessibility of DEHP may occur in invertebrates, and size-dependent desorption of uncharacterized estrogenic compounds from plastic suggest additional complexity when considering the risks of MP to aquatic organisms.

Membrane reorganization after photochemical internalization to release transferrin-biofunctionalized polystyrene microparticles

Therapeutic drug carriers can drive their cargo to their target cells. However, an obstacle is usually the entrapment of the drug inside the endolysosomal compartment, which physically impedes its actuation by the impossibility of reaching its molecular site of action. To overcome this hurdle, photochemical internalization (PCI) has been proposed, but the extent of PCI-induced membrane disruption and its capability to allow the release of microparticles is unknown. The aim of the present study was to determine if PCI allows the release of microparticles from the endolysosomal compartment to the cytosol and to analyze at the ultrastructural level the effect of PCI on the membrane surrounding the particles. Confocal microscope allowed us to detect that endolysosomal membranes suffered some disruption after PCI, evidenced by the diffusion of soluble transferrin from the endolysosomes to the cytosol and by a decrease of LAMP1-microparticles co-localization. Transmission electron microscopy (TEM) showed a decrease in the number of well-defined membranes around microparticles after PCI, and scanning TEM combined with energy dispersive x-ray revealed an increase in the width of endolysosomal membranes after treatment. These results suggest that endolysosomal membranes suffered an ultrastructure alteration after PCI, enough to liberate soluble transferrin but not the entire microparticles.

Precise Syntheses of Luminescent Polystyrene Microparticles with Encapsulated Organic Dyes for Novel Colloidal Photonic Crystals

Precise Syntheses of Luminescent Polystyrene Microparticles with Encapsulated Organic Dyes for Novel Colloidal Photonic Crystals

Enhanced Plasmonic Particle Trapping Using a Hybrid Structure of Nanoparticles and Nanorods.

Plasmon-enhanced particle trapping was demonstrated using a hybrid structure of nanoparticles and nanorods. In order to intensify localized surface plasmon resonance (LSPR), gold nanoparticles (AuNPs) were deposited on zinc oxide nanorods (ZnONRs). The synergistic effect caused by the hybrid structure was identified experimentally. Numerical analysis revealed that the LSPR-induced photophysical processes such as plasmonic heating and near-field enhancement were improved by the existence of ZnONRs. The role of the ZnONR in enhancing the particle-trapping velocity was explored by examining the scattered electric field, Poynting vector, and temperature gradient over the nanostructures calculated from the simulation. It was found that polystyrene microparticles and Escherichia coli cells were successfully trapped by using the ZnONR/AuNP plasmonic structure. A relatively high dielectric constant and nanorod geometry of ZnO enabled the hybrid substrate to enhance trapping performance, compared with a control case fabricated using only gold nanoislands.