Diameter Polystyrene Research Articles

High-Performance and Environmentally-Friendly Bulk-Wave-Acoustofluidic Devices Driven by Lead-Free Piezoelectric Materials.

Bulk-wave-acoustofluidic devices provide strong acoustic fields and high device efficiency, thereby offering high-throughput capability when processing biological samples. Such devices are typically driven by lead zirconate titanate (PZT) transducers, which contain a high content of lead, inevitably resulting in environmental and biocompatibility issues. Replacing PZT with lead-free piezoelectric materials in various ultrasonic devices is considered challenging mainly due to the inferior piezoelectric properties lead-free materials possess compared to those of PZT. In this study, through both experiments and numerical simulations, it is demonstrated that the performance of the bulk-wave-acoustofluidic devices driven by (Bi,Na)TiO3-BaTiO3-(Bi,Na)(Mn,Nb)O3 (BNT-BT-BNMN) can match that of PZT-driven devices at low power and is superior at intermediate power. It is found that the low acoustic impedance and the weak transverse mode in BNT-BT-BNMN compensate for the inferior piezoelectric properties at low power. The fact that the BNT-BT-BNMN devices outperform at intermediate power is consistent with the superior performance of the Mn-doped BNT-based piezoelectric materials compared to PZT at high power. Perfect focusing on 5- -diameter polystyrene particles at a flow rate of up to 10 mL min-1 is achieved using the BNT-BT-BNMN device at input power of 1W.

Recycled Polystyrene Waste to Triboelectric Nanogenerators: Volumetric Electromechanically Responsive Laminates from Same‐Material Contact Electrification

Millions of tonnes of polystyrene (PS) are produced annually, with only an estimated 12% being recycled. Herein, the upcycling of expanded or foamed PS waste into electromechanically responsive triboelectric laminates (TLs) is described. These TLs possess internal triboelectric dipoles offering an alternative to ferroelectric fluoropolymers, and, when manufactured into triboelectric nanogenerators (TENGs), are able to generate over 200 V and 12 μA from motion. This energy harvesting is enabled by electrospinning alternating layers of small and large diameter PS fibers, which upon friction establish an effective dipole moment within the TL. The PS‐TENG shows remarkable stability and is able to charge a 0.47 μF capacitor to 15 V in 200 s of vibration from same material contact electrification, with piezoelectric contact‐mode testing showing that a single PS laminate is comparable to state‐of‐the‐art piezoelectric fluoropolymers for overall electromechanical conversion.

Beyond two dimensions: Exploring 3D dielectrophoresis for microparticle control using carbon electrodes.

This study explores the frontiers of microparticle manipulation by introducing an actuator platform for the three-dimensional positioning of microparticles using dielectrophoresis (DEP), a technique known for its selectivity and ease of integration with microtechnology. Leveraging advancements in carbon-based devices due to their biocompatibility and electrochemical stability, our work extends the application of DEP from two-dimensional constraints to precise 3D positioning within microvolumes, employing a photolithography-based fabrication process known as Carbon-MEMS technology (C-MEMS). We present the design, finite element simulation, fabrication, and testing of this platform, which utilizes a unique combination of planar and 3D carbon microelectrodes individually addressable on a transparent substrate. This setup enables the application of DEP forces, allowing for high-throughput manipulation of multiple microparticles simultaneously, as well as displacement of individual microparticles in any desired direction. Demonstrated with spherical 1μm and 10μm diameter polystyrene microparticles, this platform features straightforward fabrication and is suitable for batch industrial production. The study concludes with a discussion of the platform's advantages and limitations, marking a significant step toward a valuable tool for studying complex biological systems.

Polystyrene Microplastics Exacerbate Candida albicans Infection Ability In Vitro and In Vivo.

Plastic pollution is an important environmental problem, and microplastics have been shown to have harmful effects on human and animal health, affecting immune and metabolic physiological functions. Further, microplastics can interfere with commensal microorganisms and exert deleterious effects on exposure to pathogens. Here, we compared the effects of 1 µm diameter polystyrene microplastic (PSMPs) on Candida albicans infection in both in vitro and in vivo models by using HT29 cells and Galleria mellonella larvae, respectively. The results demonstrated that PSMPs could promote Candida infection in HT29 cells and larvae of G. mellonella, which show immune responses similar to vertebrates. In this study, we provide new experimental evidence for the risk to human health posed by PSMPs in conjunction with Candida infections.

Fano Resonance-Assisted All-Dielectric Array for Enhanced Near-Field Optical Trapping of Nanoparticles.

Near-field optics can overcome the diffraction limit by creating strong optical gradients to enable the trapping of nanoparticles. However, it remains challenging to achieve efficient, stable trapping without heating and thermal effects. Dielectric structures have been used to address this issue but usually offer weak trap stiffness. In this work, we exploit the Fano resonance effect in an all-dielectric quadrupole nanostructure to realize a 20-fold enhancement of trap stiffness, compared to the off-resonance case. This enables a high effective trap stiffness of 1.19 fN/nm for 100 nm diameter polystyrene nanoparticles with 4.2 mW/μm2 illumination. Furthermore, we demonstrate the capability of the structure to simultaneously trap two particles at distinct locations within the nanostructure array.

Surface light propagating in a dielectric thin film generated via micro-spheres.

Light orbiting through total internal reflection within dielectric spheres or disks is called the whispering gallery mode (WGM). Recently, we have reported anomalously enhanced Raman spectra at the periphery of 3 µm diameter polystyrene (PS) microspheres on a silicon nitride (SiN) film using Raman microscopy. Here, we performed Raman measurements and optical simulation analysis of 3 µm PS spheres on a SiN film using a three-dimensional (3D) model and found that the circumferential light was generated up to 650 nm from the outer circumference of the sphere. Furthermore, a portion of the light circling the sphere travelled to the SiN film and became surface propagating light. These properties are expected to lead to development of new devices such as highly sensitive sensors, quantum optical qubits, and optical integrated circuits.

Exposure to polystyrene nanoparticles leads to changes in the zeta potential of bacterial cells

Polymer molecules, the main components of plastics, are an emerging pollutants in various environmental compartments (water, air, soil) that may induce several ecotoxicological effects on live organisms. Therefore, understanding how plastic particles interact with bacterial cell membranes is crucial in analysing their associated risks in ecosystems and human microbiota. However, relatively little is known about the interaction between nanoplastics and bacteria. The present work focuses on Staphylococcus aureus and Klebsiella pneumoniae, representing the Gram-positive and Gram-negative bacteria respectively, exposed to 100 nm diameter polystyrene nanoparticles (PS NPs). The nanoparticles attach to the cells’ membranes of both bacteria, changing their electrical charge, but without the effect of killing the cells. PS NPs caused a change in zeta potential values (both species of bacterial strains), dependent on particle concentration, pH, as well as on exposure time of bacteria to them. Through the application of AFM and FTIR techniques, the presence of PS NPs on bacterial surfaces was detected, suggesting the affinity of the particles to bacterial components, but without any changes in the morphology of the tested bacteria. The zeta potential can be more widely used in the study of interactions between nanostructures and cells.

Thermal bubble-driven impedance-based high-throughput cell counting chip design

Cell identification and enumeration are important methods within clinical and research laboratories for rapid diagnosis of relevant diseases. However, there are still many shortcomings in the current cell counting methods. In order to improve the performance of cell counting, a novel impedance-based cell counting chip based on thermal bubble drive was designed in this study. The chip is fabricated by whole-wafer processing and provides the driving force for cells through a combination of thermal bubble nozzles and microfluidic channels, integrating 100 individual detection units on a 38 mm2 size chip. Experimental and theoretical analyses have demonstrated that the chip can achieve high throughput detection of 45 000 beads/s under extreme conditions. A fourfold difference in detection voltage was obtained for both 14 and 7 µm diameter polystyrene beads. The linear fit coefficient of determination between the cell number measured by the chip and the cell number observed in reality was above 0.999 for both polystyrene beads and 211H cells, and the counting accuracy exceeded previous studies. It turns out that the chip achieves portable, low-cost, high-throughput, and high-accuracy cell counting, which is conducive to the development of impedance cell counting.

Accurate Sizing of Nanoparticles Using a High-Throughput Charge Detection Mass Spectrometer without Energy Selection.

The sizes and shapes of nanoparticles play a critical role in their chemical and material properties. Common sizing methods based on light scattering or mobility lack individual particle specificity, and microscopy-based methods often require cumbersome sample preparation and image analysis. A promising alternative method for the rapid and accurate characterization of nanoparticle size is charge detection mass spectrometry (CDMS), an emerging technique that measures the masses of individual ions. A recently constructed CDMS instrument designed specifically for high acquisition speed, efficiency, and accuracy is described. This instrument does not rely on an ion energy filter or estimates of ion energy that have been previously required for mass determination, but instead uses direct, in situ measurements. A standardized sample of ∼100 nm diameter polystyrene nanoparticles and ∼50 nm polystyrene nanoparticles with amine-functionalized surfaces are characterized using CDMS and transmission electron microscopy (TEM). Individual nanoparticle masses measured by CDMS are transformed to diameters, and these size distributions are in close agreement with distributions measured by TEM. CDMS analysis also reveals dimerization of ∼100 nm nanoparticles in solution that cannot be determined by TEM due to the tendency of nanoparticles to agglomerate when dried onto a surface. Comparing the acquisition and analysis times of CDMS and TEM shows particle sizing rates up to ∼80× faster are possible using CDMS, even when samples ∼50× more dilute were used. The combination of both high-accuracy individual nanoparticle measurements and fast acquisition rates by CDMS represents an important advance in nanoparticle analysis capabilities.

High-Resolution Dielectric Characterization of Single Cells and Microparticles Using Integrated Microfluidic Microwave Sensors

Microwave sensors can probe intrinsic material properties of analytes in a microfluidic channel at physiologically relevant ion concentrations. While microwave sensors have been used to detect single cells and microparticles in earlier studies, the synergistic use and comparative analysis of microwave sensors with optical microscopy for material classification and size tracking applications have been scarcely investigated so far. Here we combined microwave and optical sensing to differentiate microscale objects based on their dielectric properties. We designed and fabricated two types of planar sensor: a Coplanar Waveguide Resonator (CPW) and a Split-Ring Resonator (SRR). Both sensors possessed sensing electrodes with a narrow gap to detect single cells passing through a microfluidic channel integrated on the same chip. We also show that standalone microwave sensors can track the relative changes in cellular size in real-time. In sensing single 20-micron diameter polystyrene particles, Signal-to-Noise ratio values of approximately 100 for CPW and 70 for SRR sensors were obtained. These findings demonstrate that microwave sensing technology can serve as a complementary technique for single-cell biophysical experiments and microscale pollutant screening.

Microplastic pollution destabilized the osmoregulatory metabolism but did not affect intestinal microbial biodiversity of earthworms in soil

Metabolomic and gut microbial responses of soil fauna to environmentally relevant concentrations of microplastics indicate the potential molecular toxicity of microplastics; however, limited data exist on these responses. In this study, earthworms (Eisenia fetida) were exposed to spherical (25–30 μm diameter) polystyrene microplastic-contaminated soil (0.02%, w:w) for 14 days. Changes in weight, survival rate, intestinal microbiota and metabolic responses of the earthworms were assessed. The results showed that polystyrene microplastics did not influence the weight, survival rate, or biodiversity of the gut microbiota, but significantly decreased the relative abundance of Bacteroidetes at the phylum level. Moreover, polystyrene microplastics disturbed the osmoregulatory metabolism of earthworms, as indicated by the significantly decreased betaine, myo-inositol and lactate, and increased 2-hexyl-5-ethyl-furan-3-sulfonic acid at the metabolic level. This study provides important insights into the molecular toxicity of environmentally relevant concentrations of polystyrene microplastics on soil fauna.

Stable Negative Optical Torque in Optically Bound Nanoparticle Dimers.

Negative optical torque is a counterintuitive optomechanical phenomenon that can emerge in light-assembled nanoparticle (NP) clusters (i.e., optical matter) under circular polarization. However, in experiments, stable negative torque was limited to optical matter with 3 or more NPs. Here, we show that by increasing the particle size, the sign of optical torque can be reversed in optical matter dimers, where stable negative torque arises in dimers of 300 nm diameter Au or 490 nm diameter polystyrene NPs. Our computational analysis reveals that the multipolar resonances in large NPs can enhance the forward scattering along the spin angular momentum (SAM) direction of light, creating a recoil negative torque due to momentum conservation. The observation of stable negative torque in dimers pushes the limit to the smallest optical matter, demonstrating the universal existence of negative torque in such a system. The underlying principle also provides new strategies for making light-driven nanomotors.

Optimization of a leaky plasmonic metal–insulator–metal nanopillar array for low concentration biosensing applications

The research focuses on optimization of a leaky metal–insulator–metal (MIM) nanopillar array design for the detection of sub-100 nm viruses. Here we have explored different MIM nanopillar and array geometries along with the insulator layer material to tune the plasmonic field leakage. For the optimized design, we observe a sensitivity of the surface refractive index change of − 101.68 n m R I U − 1 . Using 100 nm diameter polystyrene particles, a sensitivity of 17.66 nm/decade was achieved with a detection limit of one particle. The optimized structures thus demonstrate a homogeneous surface sensitivity over a large active sensing area for sub-100 nm virus detection.

Measuring nanoparticles in liquid with attogram resolution using a microfabricated glass suspended microchannel resonator

The use of nanoparticles has been growing in various industrial fields, and concerns about their effects on health and the environment have been increasing. Hence, characterization techniques for nanoparticles are essential. Here, we present a silicon dioxide microfabricated suspended microchannel resonator (SMR) to measure the mass and concentration of nanoparticles in a liquid as they flow. We measured the mass detection limits of the device using laser Doppler vibrometry. This limit reached a minimum of 377 ag that correspond to a 34 nm diameter gold nanoparticle or a 243 nm diameter polystyrene particle, when sampled every 30 ms. We compared the fundamental limits of the measured data with an ideal noiseless measurement of the SMR. Finally, we measured the buoyant mass of gold nanoparticles in real-time as they flowed through the SMR.

Robust and High‐Efficient Fabrication of Gold Triangles Array on Optical Fiber Tip for Laser Mode Locking

AbstractThe plasmonic metasurfaces composed of gold triangles (GTAs) array have been directly fabricated onto the optical fiber tip (OFT) using a modified self‐assembly nanosphere lithography technology, featuring intrinsic good compatibility, high‐quality, low‐cost, time‐saving, and large‐scale fabrication. Then, the first experimental realization of all‐fiber mode‐locked lasers based on GTAs array as saturable absorber is reported. The linear transmission spectra of the different‐sized GTAs array fabricated using different‐sized polystyrene (PS) microspheres (diameter: 1000, 1100, 1300, and 1600 nm) demonstrate highly tunable localized surface plasmon resonance (LSPR) across a broad spectral range from 1295 to 1985 nm, and its nonlinear transmission spectra present a larger modulation depth (maximum: 11.5%) when the LSPR is close to the 1550 nm. When inserting the GTAs@OFT samples fabricated using 1100‐nm diameter and 1300‐nm diameter PS microspheres into a fiber‐ring cavity, the all‐fiber picosecond (≈3.7 ps) soliton mode‐locked lasers with high output power (>10 mW) are successfully achieved at optical communication wavelength of 1.5 µm. The findings expand the scopes of plasmonic metasurface composed of GTAs array as saturable absorber, and may pave the way for mass production of ultrafast all‐fiber lasers and novel all‐fiber devices for optical communications, bio‐sensing, and bio‐imaging.

Strategy for optimizing experimental settings for studying low atomic number colloidal assemblies using liquid phase scanning transmission electron microscopy

Observing processes of nanoscale materials of low atomic number is possible using liquid phase electron microscopy (LP-EM). However, the achievable spatial resolution (d) is limited by radiation damage. Here, we examine a strategy for optimizing LP-EM experiments based on an analytical model and experimental measurements, and develop a method for quantifying image quality at ultra low electron dose De using scanning transmission electron microscopy (STEM). As experimental test case we study the formation of a colloidal binary system containing 30 nm diameter SiO2 nanoparticles (SiONPs), and 100 nm diameter polystyrene microspheres (PMs). We show that annular dark field (DF) STEM is preferred over bright field (BF) STEM for practical reasons. Precise knowledge of the material's density is crucial for the calculations in order to match experimental data. To calculate the detectability of nano-objects in an image, the Rose criterion for single pixels is expanded to a model of the signal to noise ratio obtained for multiple pixels spanning the image of an object. Using optimized settings, it is possible to visualize the radiation-sensitive, hierarchical low-Z binary structures, and identify both components.

Targeting inflammatory monocytes by immune-modifying nanoparticles prevents acute kidney allograft rejection

Inflammatory monocytes are a major component of the cellular infiltrate in acutely rejecting human kidney allografts. Since immune-modifying nanoparticles (IMPs) bind to circulating inflammatory monocytes via the specific scavenger receptor MARCO, causing diversion to the spleen and subsequent apoptosis, we investigated the therapeutic potential of negatively charged, 500-nm diameter polystyrene IMPs to prevent kidney allograft rejection. Kidney transplants were performed from BALB/c (H2d) to C57BL/6 (H2b) mice in two groups: controls (allo) and allo mice infused with IMPs. Groups were studied for 14 (acute rejection) or 100 (chronic rejection) days. Allo mice receiving IMPs exhibited superior survival and markedly less acute rejection, with better kidney function, less tubulitis, and diminished inflammatory cell density, cytokine and cytotoxic molecule expression in the allograft and lower titers of donor-specific IgG2c antibody in serum at day 14, as compared to allo mice. Cells isolated from kidneys from allo mice receiving IMPs showed reduced Ly6Chi monocytes, CD11b+ cells and NKT+ cells compared to allo mice. IMPs predominantly bound CD11b+ cells in the bloodstream and CD11b+ and CD11c-B220+ marginal zone B cells in the spleen. In the spleen, IMPs were found predominantly in red pulp, colocalized with MARCO and expression of cleaved caspase-3. At day 100, allo mice receiving IMPs exhibited reduced macrophage M1 responses but were not protected from chronic rejection. IMPs afforded significant protection from acute rejection, inhibiting both innate and adaptive alloimmunity. Thus, our current experimental findings, coupled with our earlier demonstration of IMP-induced protection in kidney ischemia-reperfusion injury, identify IMPs as a potential induction agent in kidney transplantation.

SERS using nanostar‐in‐cavity structures

AbstractParticle in cavity nanostructures were produced by sedimentation of silver nanostars (AgNSs) onto sphere segment void (SSV) cavity structures produced by electrodeposition of gold around templates formed by assembling close packed monolayer arrays of 220 or 600 nm diameter polystyrene spheres. The resulting AgNS@SSV nanostructures were characterized by scanning electron microscopy and their performance as substrates for surface enhanced Raman spectroscopy (SERS) was examined. The enhancement factors obtained for the different structures were evaluated using benzenethiol as Raman probe, which adsorbs on Ag and Au to form a monolayer with uniform coverage, so allowing the enhancement to be quantified. Higher enhancements were obtained for the AgNSs@SSV substrates as compared with the gold SSV structures. The greatest enhancements were obtained when matching cavity and nanostar dimension so that only one nanostar could be accommodated in the cavity. The AgNS@SSV substrates were then shown to be promising substrates for the highly sensitive detection of dyes and, particularly, for the lake‐pigment cochineal lake, providing useful information and novel analytical tool for application in the field of cultural heritage diagnostics and conservation.

Understanding the Effect of Pore Size on Electrochemical Capacitive Performance of MXene Foams.

Wearable electronics demand energy storage devices with high energy density and fast charging-discharging rates. Although various porous electrodes have been constructed, the effect of pore size on the capacitive performance of 2Dnanomaterials has been rarely studied. Herein, flexible MXene foams with significantly different pore structures are fabricated using varying diameter polystyrene (PS) spheres (80, 310, and 570nm), whichshows uniform pores and interconnected pores providing enough active sites and a good electrical connection for electron transfer. Noteworthy, when MXene flakes and templates (310nm) have a similar size, the foam delivers the highest gravimetric capacitance of 474± 12 F g-1 at 2mV s-1 than others. Additionally, the mass ratio between MXene and PS controls the packing density of foams influencing the inner resistance of foam electrodes. A carbon nanotube is introduced to further improve the electrical conductivity of foams to achieve a capacitance of 462± 8 F g-1 at 2mV s-1 and retains 205± 10 F g-1 at 1000mV s-1 , demonstrating promises in energy storage applications and providingan insightful guidance for designing 2D nanomaterials-based porous electrodes for supercapacitors.

Theoretical and experimental analysis of negative dielectrophoresis‐induced particle trajectories

Many biomedical analysis applications require trapping and manipulating single cells and cell clusters within microfluidic devices. Dielectrophoresis (DEP) is a label‐free technique that can achieve flexible cell trapping, without physical barriers, using electric field gradients created in the device by an electrode microarray. Little is known about how fluid flow forces created by the electrodes, such as thermally driven convection and electroosmosis, affect DEP‐based cell capture under high conductance media conditions that simulate physiologically relevant fluids such as blood or plasma. Here, we compare theoretical trajectories of particles under the influence of negative DEP (nDEP) with observed trajectories of real particles in a high conductance buffer. We used 10‐µm diameter polystyrene beads as model cells and tracked their trajectories in the DEP microfluidic chip. The theoretical nDEP trajectories were in close agreement with the observed particle behavior. This agreement indicates that the movement of the particles was highly dominated by the DEP force and that contributions from thermal‐ and electroosmotic‐driven flows were negligible under these experimental conditions. The analysis protocol developed here offers a strategy that can be applied to future studies with different applied voltages, frequencies, conductivities, and polarization properties of the targeted particles and surrounding medium. These findings motivate further DEP device development to manipulate particle trajectories for trapping applications.