Polystyrene Spheres Research Articles

Lipid Corona Formation on Micro- and Nanoplastic Particles Modulates Uptake and Toxicity in A549 Cells.

Plastic waste is a global issue leaving no continents unaffected. In the environment, ultraviolet radiation and shear forces in water and land contribute to generating micro- and nanoplastic particles (MNPP), which organisms can easily take up. Plastic particles enter the human food chain, and the accumulation of particles within the human body is expected. Crossing epithelial barriers and cellular uptake of MNPP involves the interaction of plastic particles with lipids. To this end, we generated unilamellar vesicles from POPC (1-palmitoyl-2-oleoyl-glycero-3-phosphocholine) and POPS (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine) and incubated them with pristine, carboxylated, or aminated polystyrene spheres (about 1 µm in diameter) to generate lipid coronas around the particles. Lipid coronas enhanced the average particle sizes and partially changed the MNPP zeta potential and polydispersity. In addition, lipid coronas led to significantly enhanced uptake of MNPP particles but not their cytotoxicity, as determined by flow cytometry. Finally, adding proteins to lipid corona nanoparticles further modified MNPP uptake by reducing the uptake kinetics, especially in pristine and carboxylated plastic samples. In conclusion, our study demonstrates for the first time the impact of different types of lipids on differently charged MNPP particles and the biological consequences of such modifications to better understand the potential hazards of plastic exposure.

Synthesis of microporous hollow spherical polystyrene carbons for the highly efficient CO2 adsorption and selectivity

Carbon materials with economic and high adsorption capacity attract much attention to reducing fossil fuel and industrial CO2 emissions. For this purpose, porous hollow spheres with high surface area and micropore volume, morphologically resembling fullerene or soccer balls, were first produced from the synthesized polystyrene by hydrothermal and conventional activation. The highest micropore volume and BET surface area were found in PS-hydroHCl with 0.61 cm3/g and 1481 m2/g, respectively. The CO2 adsorption capacities of PS-hydroHCl at 0 and 25 °C were relatively high and were obtained as 6.25 and 3.62 mmol/g, respectively. It was determined that all microporous spheres were influential in the isosteric heat of adsorption range of 17–26 kJ/mol, that is, typical CO2 physical adsorption. It has been found that hydrothermally synthesized PS-hydro and PS-hydroHCl contain higher amounts of oxygen than PS and PSHCl produced according to the conventional method. In addition, CO2/N2 selectivity at 25 °C, PS-hydroHCl, was three times more effective than PSHCl. As a result, it can be said that the synthesis of porous hollow microspheres is simple, and the starting material (polystyrene) is cheap and abundant; high CO2 adsorption and effective CO2/N2 selectivity will be promising for industrial applications.

Thickness control of dispersion in opal photonic crystals

Opals are naturally occurring photonic crystals which can be formed easily using low-cost self-assembly methods. While the optical behaviour of opals has received significant attention over the last number of decades, there is limited information on the effect of crystal thickness on the optical properties they display. Here, the relationship between volume fraction and crystal thickness is established with an evaporation-induced self-assembly (EISA) method of formation. The extent to which thickness can be used to manipulate the optical properties of the crystals is explored, focusing on the change in the photonic band gap (PBG). Microscopical structural characterization and angle-resolved transmission spectroscopy are used to examine the quality of the photonic crystals formed using different volume fractions of polystyrene spheres, with thicknesses up to 37 layers grown from volume fractions of 0.125%. This work provides a direct correlation between sphere solution volume fraction and crystal thickness, and the associated optical fingerprint of opal photonic crystals. Maximum thickness is examined, which is shown to converge to a narrow range over several evaporation rates. We identify the criteria required to achieve thickness control in relatively fast evaporation induced self-assembly while maintaining structural quality, and the change to the spectroscopic signature to the (111) stopband and higher order (220) reflections, under conditions where a less ordered photonic crystals are formed.

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.

Using optimized particle imaging of micro-Raman to characterize microplastics in water samples

Characterizing the chemical properties, morphologies, size, and quantities of microplastics (MPs) in water samples with high precision is critically important for understanding the environmental behaviors of MPs. Traditional detection methods, such as Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy point-by-point detection, provide worthy reference techniques but are time- and labor-consuming. We established a super time-saving and high-precision technique to characterize MPs using micro-Raman automatic particle identification (MR-API). Based on the identification of PS spheres, screen magnification, exposure time, and the number of scans are selected as crucial detection parameters for MR-API analysis, which highly affect the precision of the results. Detecting particles down to 1 μm requires magnification of the mosaic until the scale showed 200 μm. The recommended setting parameters were 83.33 or 100 ms exposure time, 20 scans, 7 mW laser power, and 1 μm image pixel size, suitable for polystyrene (PS), polypropylene (PP), polyethylene terephthalate (PET), polyethylene (PE), polyvinyl chloride (PVC), and polyamide (PA) particles detection. With the complete procedure of MR-API measurements, the recovery of MPs was 61.67–90.00 %. To validate the feasibility of the MR-API, the method was used to detect samples of known plastic types (mask leachates) and unknown plastic types (urban lake). A total of 4540 particles in the sample of mask leachates consuming 35 h 50 min 43 s, and 0.92 ± 0.49 % of particles were identified as MPs. The urban river sample efficiently identified PP, PET, PE, PVC, PS, EVA, and VC/VAC MPs using this method. The detected MPs size ranged from 8.3 to 5000 μm, saving 75.03 % and 58.38 % of the time compared to the conventional micro-FTIR and micro-Raman point-by-point methods, respectively. Therefore, this method is effective for detecting MPs in the environmental samples and has excellent prospects.

Spreading Solution Additives Governs the Quality of Polystyrene Particle-Based Two-Dimensional Opals.

Two-dimensional polystyrene sphere opals are important materials for nanotechnology applications and fundamental nanoscience research. They are a facile and inexpensive nanofabrication tool, but the quality factor of these opals has drastic differences between reports. Additives like ethanol, ions, and organic molecules in the aqueous particle spreading solution are known to affect the quality factor and growth efficiency of the produced opals. However, a systematic study on the effect and optimization of some of the most effective additives has not been reported until now. Here, we investigate the influence of additives on the growth efficiency and quality factor of such monolayers formed at the air-water interface without the use of a Langmuir-Blodgett trough. The additives induced large variations in the monolayer quality factor and growth efficiency, and we found that the ideal additive content of the spreading agents is 30 wt % < cethanol < 70 wt %, 0 < cH2SO4 < 30.5 mM, and 0 < csty < 255.0 mM. This study provides a guideline for the rational composition and additive content of the spreading solution to obtain high-quality two-dimensional opals for further applications in nanofabrication and photonics and will enable researchers and application engineers to produce standardized nanofabrication materials.

Combined effects of salinity and polystyrene microplastics exposure on the Pacific oysters Crassostrea gigas: Oxidative stress and energy metabolism

Microplastics (MPs) pollution and salinity variation are two environmental stressors, but their combined effects on marine mollusks are rarely known. Oysters (Crassostrea gigas) were exposed to 1 × 104 particles L−1 spherical polystyrene MPs (PS-MPs) of different sizes (small polystyrene MPs (SPS-MPs): 6 μm, large polystyrene MPs (LPS-MPs): 50–60 μm) under three salinity levels (21, 26, and 31 psu) for 14 days. Results demonstrated that low salinity reduced PS-MPs uptake in oysters. Antagonistic interactions between PS-MPs and low salinity mainly occurred, and partial synergistic effects were mainly induced by SPS-MPs. SPS-MPs induced higher lipid peroxidation (LPO) levels than LPS-MPs. In digestive glands, low salinity decreased LPO levels and glycometabolism-related gene expression, which was related to salinity levels. Low salinity instead of MPs mainly affected metabolomics profiles of gills through energy metabolism and osmotic adjustment pathway. In conclusion, oysters can adapt to combined stressors through energy and antioxidative regulation.

Antireflection Structures for VIS and NIR on Arbitrarily Shaped Fused Silica Substrates with Colloidal Polystyrene Nanosphere Lithography.

Antireflective (AR) nanostructures offer an effective, broadband alternative to conventional AR coatings that could be used even under extreme conditions. In this publication, a possible fabrication process based on colloidal polystyrene (PS) nanosphere lithography for the fabrication of such AR structures on arbitrarily shaped fused silica substrates is presented and evaluated. Special emphasis is placed on the involved manufacturing steps in order to be able to produce tailored and effective structures. An improved Langmuir-Blodgett self-assembly lithography technique enabled the deposition of 200 nm PS spheres on curved surfaces, independent of shape or material-specific characteristics such as hydrophobicity. The AR structures were fabricated on planar fused silica wafers and aspherical planoconvex lenses. Broadband AR structures with losses (reflection + transmissive scattering) of <1% per surface in the spectral range of 750-2000 nm were produced. At the best performance level, losses were less than 0.5%, which corresponds to an improvement factor of 6.7 compared to unstructured reference substrates.

The effect of planktivorous fish (juvenile Perca fluviatilis) on the taxonomic diversity of microplastic particles-colonized bacterial community

Very few studies have investigated the influence of fish on the degradation rate of microplastic particles (MPs). It could be expected that their effect might be not only direct, through digestion and passage through the gut, but also indirect, through the alteration of the density and composition of the bacterial community on the surface of MPs. This study aims to test the short-term effects of fish presence altering the water chemical parameters and the abundance and genetic diversity of the aquatic bacteria colonising MPs, which may contribute to their faster degradation. This was tested in a triplicate experiment, with each replicate lasting 10 days in the presence or absence of spherical MPs, polystyrene (Ps) or polyethylene (Pe) and the presence or absence of a perch. The animal was separated from the MPs with a plankton net. We determined the chemical parameters of the water, the number of bacteria in the water and on the MPs’ surface, the taxonomic diversity of bacteria in the water and those present on the MPs using 16S rRNA gene (16S rDNA) sequencing, and the alterations of the MPs’ surface using a scanning electron microscope. The exposure to fish increased the concentration of ammonium, nitrates, and orthophosphates and the number of bacteria in the water, which in turn resulted in an increase in the abundance of bacteria and the number of taxa at the family level on the MPs’ surface. The positive effect of fish exudates on the abundance of bacteria on MPs’ surface was greater in the case of Pe than in Ps. The observed effects did not affect the MPs’ surface in any of the types of plastic during the experiment, but they may play a significant role in MPs decomposition over a longer than applied time period.

Investigations on the optical forces from three mainstream optical resonances in all-dielectric nanostructure arrays.

Light can exert radiation pressure on any object it encounters, and the resulting optical force can be used to manipulate particles at the micro- or nanoscale. In this work, we present a detailed comparison through numerical simulations of the optical forces that can be exerted on polystyrene spheres of the same diameter. The spheres are placed within the confined fields of three optical resonances supported by all-dielectric nanostructure arrays, including toroidal dipole (TD), anapoles, and quasi-bound states in continuum (quasi-BIC) resonances. By elaborately designing the geometry of a slotted-disk array, three different resonances can be supported, which are verified by the multipole decomposition analysis of the scattering power spectrum. Our numerical results show that the quasi-BIC resonance can produce a larger optical gradient force, which is about three orders of magnitude higher than those generated from the other two resonances. The large contrast in the optical forces generated with these resonances is attributed to a higher electromagnetic field enhancement provided by the quasi-BIC. These results suggest that the quasi-BIC resonance is preferred when one employs all-dielectric nanostructure arrays for the trapping and manipulation of nanoparticles by optical forces. It is important to use low-power lasers to achieve efficient trapping and avoid any harmful heating effects.

Quantification of Very Low Concentrations of Colloids with Light Scattering Applied to Micro(Nano)Plastics in Seawater

The detection and quantification of micro(nano)plastics in the marine environment are essential requirements to understand the full impacts of plastic pollution on the ecosystem and human health. Here, static light scattering (SLS) and dynamic (DLS) light scattering techniques are assessed for their capacity to detect colloidal particles with diameters between d = 0.1 and 0.8 µm at very low concentrations in seawater. The detection limit of the apparatus was determined using model monodisperse spherical polystyrene latex particles with diameters of 0.2 µm and 0.5 µm. It is shown that the concentration and size of colloids can be determined down to about 10−6 g/L. Light scattering measurements on seawater obtained from different locations in Western Europe show that colloidal particles were detected with DLS in seawater filtered through 0.8 µm pore size filters. The concentration of these particles was not higher than 1 µg/L, with an average diameter of about 0.6 µm. We stress that these particles are not necessarily plastic. No particles were detected after filtration through 0.45 µm pore size filters.

Ефективна пластична поведінка пористих матеріалів зі структурою інверсного опалу

Based on the theoretical principles of the mechanics of composites, the effective plastic behavior of a porous material with a periodic inverse opal structure under uniaxial loading was studied in detail by means of finite element modeling. The creation of such materials is based on the inversion of pores and skeleton of partially sintered dense packing of polystyrene spheres. Electrodeposited nickel was used as the skeleton of the porous material. According to the macroscopic uniaxial loading or unloading, was finding a stress-strain state at the meso-level. For this, equilibrium equations were solved at the meso-level using special boundary conditions for a periodic unit cell. Such boundary conditions relate the problem of equilibrium at the meso-level with the "effective" deformations of the composite. This made it possible to calculate macroscopic residual strains after a cycle of uniaxial loading and unloading and iteratively find the value of effective stress corresponding to residual strains of 0.2%. In this way, the yield strength of inverse opal for uniaxial loading is calculated. At the same time, as a result of finite-element calculations, the transverse deformations coefficient (plastic Poisson ratio) is determined. This coefficient, in turn, makes it possible to approximate the general plastic behavior of the metamaterial by an elliptic yield curve in the plane of invariants of the stress tensor. Invariants mean average pressure and von Mises stress. These calculations were performing for several cases of the inverse opal structure, both with and without an additional coating. Yield stresses under any type of material loading are very sensitive to porosity. In particular, the application of an additional coating, even with a thickness less than 0,05 of the diameter of the spherical pores (initial polymer particles), causes an increase in the yield strength several times. Keywords: metamaterials, inverse opal, porous plasticity model, micromechanics, theory of plasticity.

Novel efficient solar spherical evaporators with adjustable pores to control water supply and evaporation

Solar-driven interfacial evaporation is a promising seawater desalination technique. The limited evaporation rate in evaporators used up to now is due to the poor balance between the water supply, and the evaporation rate at the solar absorber evaporation surface. Here, we report the fabrication of novel and efficient spherical solar evaporators, whose adjustable pore size and porosity accelerate water evaporation. These evaporators are porous coating made of vertical array carbon nanotubes (VACNT) / cellulose nanofibers (CNF) / polyvinyl alcohol (PVA), which are wrapped around light-expanded polystyrene (EPS) spheres. The experimental results show that the drying time and the PVA content decisively determine the pore size and, subsequently, the water content. The optimized evaporators manifest a high evaporation rate of 1.23 kg·m−2·h−1 and efficiency of 76.3 % under 1 sun illumination, which is 3.2 times higher than the evaporation rate of pure water under the same conditions. The fabricated evaporators are applied to produce clean water from simulated seawater, and the results show that the metal ion concentrations in the collected water are far below the upper levels of the WHO (World Health Organization) International Standards.

Self-organized patterning on azo molecular glass film via optical near-field effect

Self-organized surface patterning has attracted great research interest ranging from scientific understanding to various applications. Here, we report a unique patterning behavior observed on an azo molecular glass film with polystyrene microspheres on the surface upon irradiation with a circularly polarized laser beam. Photoinduced submicron hillocks are found to organize into concentric arrays around isolated polystyrene spheres, while more complex patterns are observed around two or more spheres close to each other. The irradiation first creates surface relief rings encircling the spheres and then the rings split into hillocks arranged in circular arrays with increasing exposure time. Pattern formation is shown to be controlled by synergy from the optical near-field of polystyrene spheres with the spontaneous hillock formation characteristics of the molecular glass film upon light irradiation. This work is beneficial to deepening the understanding of light–matter interactions and is expected to be applied in different areas.

Modeling and Experiments of Droplet Evaporation with Micro or Nano Particles in Coffee Ring or Coffee Splat.

Experimental and numerical experiments were carried out to study the coffee rings or coffee splats formed by droplet evaporation with micro or nano polystyrene sphere particles (Dp = 10 μm or 100 nm). Particle image velocimetry (PIV) and a high-resolution camera were used in this experiment, along with a temperature-controlled heater and a data-acquisition computer. The results showed that a nano particle could form a homogeneous coffee splat, instead of the common coffee ring formed when using micro particles. In order to account for this phenomenon, this paper developed a complex multiphase model, one which included the smooth particle hydrodynamics (SPH) fluid model coupled with the van der Waals equation of state for droplet evaporation, the rigid particle model of finite-size micro particles, and the point-particle model of the nanometer particles. The numerical simulation was operated on a GPU-based algorithm and tested by four validation cases. A GPU could calculate 533 times the speed of a single-core CPU for about 300,000 particles. The results showed that, for rigid solid particles, the forms emerged spontaneously on the wall, and their structure was mainly affected by the boundary wettability, and less affected by the fluid flow and thermal condition. When the wall temperature was low, it was easier for the particles to be deposited on the contact line. At high wall temperature, the coffee ring effect would be weakened, and the particles were more likely to be deposited in the droplet center. The hydrophilic surface produced a larger coffee ring compared to the hydrophobic surface. The experimental and numerical results proved that particle size could play a significant role during the particle deposition, which may be a possible route for producing uniform-distributed and nano-structure coatings.

Magnetic relaxation switching immunoassay based on “limited-magnitude” particles for sensitive quantification of aflatoxin B1

Aflatoxin B1 (AFB1) is a highly toxic and carcinogenic chemical substance that endangers food safety and human health. Magnetic relaxation switching (MRS) immunosensors are utilized in a variety of applications in food analysis due to its resistance to matrix interferences, but they often suffer from magnetic separation-based multi-washing steps and low sensitivity. Herein, we propose novel MRS strategy for the sensitive detection of AFB1 using “Limited-Magnitude” size particles: a single millimeter sized polystyrene spheres (PSmm) and 150 nm superparamagnetic nanoparticles (MNP150). Only a single PSmm is used as the microreactor to enhance all of the magnetic signal on its surface in high concentration by an immune competitive response, successfully preventing signal dilution, which can be transferred by pipette, simplifying the process of separation and washing. The established single polystyrene sphere magnetic relaxation switch biosensor (SMRS) was able to quantify AFB1 from 0.02 to 200 ng/mL with a detection limit of 14.3 pg/mL. SMRS biosensor has been successfully used for the detection of AFB1 in wheat and maize samples, and the results in agreement with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS). Benefiting from high sensitivity and convenient operation, the simple and enzyme-free method is promising in trace small molecules applications.

Evaluations of nanoparticle capture and transport methods in dielectric bowtie core capillaries.

We propose a flexibly tunable and low-loss optical burette with an all-dielectric bowtie core capillary structure, where nanoparticle arrays can be transported bidirectionally with incident light from one end. Multiple hot spots, acting as optical traps, are periodically distributed at the center of the bowtie cores along the propagation direction because of the mode interference effect of guided lights. By adjusting the beam waist position, the hot spots continuously move across the entire capillary length; thus, trapped nanoparticles also transfer with the hot spots. The bidirectional transfer can be realized simply by changing the beam waist in the forward or backward direction. We confirmed that nanosized polystyrene spheres can be bidirectionally moved along a capillary length of ≈ 20 µm. Furthermore, the magnitude of the optical force can be adjusted using the incident angle and beam waist width, whereas the trapping period can be adjusted using the incident wavelength. These results were evaluated using the finite-difference time-domain method. We believe that this new approach can be extensively used in the field of biochemical and life sciences because of the properties of an all-dielectric structure, bidirectional transportation, and single incident light.

Electrochemically active porous carbon nanospheres prepared by inhibition of pyrolytic condensation of polymers

Porous carbon is a pivotal material for electrochemical applications. The manufacture of porous carbon has relied on chemical treatments (etching or template) that require processing in all areas of the carbon/carbon precursor. We present a unique approach to preparing porous carbon nanospheres by inhibiting the pyrolytic condensation of polymers. Specifically, the porous carbon nanospheres are obtained by coating a thin film of ZnO on polystyrene spheres. The porosity of the porous carbon nanospheres is controlled by the thickness of the ZnO shell, achieving a BET-specific area of 1,124m2/g with a specific volume of 1.09cm3/g. We confirm that under the support force by the ZnO shell, a hierarchical pore structure in which small mesopores are connected by large mesopores is formed and that the pore-associated sp3 defects are enriched. These features allow full utilization of the surface area of the carbon pores. The electrochemical capacitive performance of porous carbon nanospheres was evaluated, achieving a high capacitance of 389 F/g at 1 A/g, capacitance retention of 71% at a 20-fold increase in current density, and stability up to 30,000 cycles. In particular, we achieve a specific area-normalized capacitance of 34.6 μF/cm2, which overcomes the limitations of conventional carbon materials.

In-Plane Rotation of Prolate Colloids Adhered to a Planar Substrate in the Presence of Flow.

Micron-size spherical polystyrene colloidal particles are mechanically stretched to a prolate geometry with desirable aspect ratios. The particles in an aqueous medium with specific ionic concentration are then introduced into a microchannel and allowed to settle on a glass substrate. In the presence of unidirectional flow, the loosely adhered particles in the secondary minimum of surface interaction potential are easily washed off, but the remnant in the strong primary minimum preferentially aligns with the flow direction and exercises in-plane rotation. A rigorous theoretical model is constructed to account for filtration efficiency in terms of hydrodynamic drag, intersurface forces, reorientation of prolate particles, and their dependence on flowrate and ionic concentration.

Critical gaps in nanoplastics research and their connection to risk assessment.

Reports of plastics, at higher levels than previously thought, in the water that we drink and the air that we breathe, are generating considerable interest and concern. Plastics have been recorded in almost every environment in the world with estimates on the order of trillions of microplastic pieces. Yet, this may very well be an underestimate of plastic pollution as a whole. Once microplastics (<5mm) break down in the environment, they nominally enter the nanoscale (<1,000nm), where they cannot be seen by the naked eye or even with the use of a typical laboratory microscope. Thus far, research has focused on plastics in the macro- (>25mm) and micro-size ranges, which are easier to detect and identify, leaving large knowledge gaps in our understanding of nanoplastic debris. Our ability to ask and answer questions relating to the transport, fate, and potential toxicity of these particles is disadvantaged by the detection and identification limits of current technology. Furthermore, laboratory exposures have been substantially constrained to the study of commercially available nanoplastics; i.e., polystyrene spheres, which do not adequately reflect the composition of environmental plastic debris. While a great deal of plastic-focused research has been published in recent years, the pattern of the work does not answer a number of key factors vital to calculating risk that takes into account the smallest plastic particles; namely, sources, fate and transport, exposure measures, toxicity and effects. These data are critical to inform regulatory decision making and to implement adaptive management strategies that mitigate risk to human health and the environment. This paper reviews the current state-of-the-science on nanoplastic research, highlighting areas where data are needed to establish robust risk assessments that take into account plastics pollution. Where nanoplastic-specific data are not available, suggested substitutions are indicated.