Surface Of Polystyrene Microspheres Research Articles

Polystyrene microspheres with ultra-rough surfaces engineered using RIE technique and applied using SERS.

In this study, we successfully fabricated two ultra-rough surfaces based on polystyrene (PS) microspheres by employing the reactive ion etching (RIE) technique. Elemental analysis confirmed a stable AlF3 composition of the structures of these surfaces. We proposed the mechanism of the formation of these surfaces and performed SERS-related tests; the prepared substrates exhibited excellent SERS performance.

Surface interaction of vancomycin with polystyrene microplastics and its effect on human serum albumin

Microplastics have a well-documented ability to adsorb various chemicals and contaminants found in the environment. By similar mechanisms, when medicines are stored in plastic packaging, the leaching of plastics into the contents poses the risk of possible toxicity and decreased drug efficacy. The work thus examines the presence of two categories of anthropogenic materials – microplastics (MPs) and medications - with their possible combined effects and fate in biological systems. A study on the kinetics and isotherm of the adsorption of vancomycin hydrochloride on the surface of polystyrene microspheres is performed, and the best-fitting models are obtained respectively as the pseudo-second-order model and the Temkin isotherm. Further, the interaction of each of, the drug, MPs and drug-adsorbed MPs with human serum albumin (HSA), the model protein chosen to validate the potential toxicity in humans, is determined by fluorescence spectroscopy. A thermodynamic analysis of this protein-ligand interaction shows that the process is spontaneous, endothermic and entropically favoured, and that hydrophobic forces operate between the interacting species. An unfolding of HSA is observed, disrupting its functions like the esterase activity. Competitive binding experiments with Warfarin and Ibuprofen as specific site markers on HSA reveal that all the studied ligands bind non-specifically to HSA.

Conductometric and Potentiometric Titration of Carboxyl Groups in Polymer Microspheres

A laboratory procedure has been suggested for determining the concentration of carboxyl groups at the surface of polystyrene microspheres at the latex concentration of a few hundredths of weight percentage (the COOH groups concentration below 4 × 10−4 mol/L). The procedure is based on conductometric and potentiometric titration. The influence of polymer particles concentration in the system, ionic strength of the solution, titration duration, and the system inertness on the obtained values of the carboxyl groups concentration and the determination accuracy have been investigated.

Latex Agglutination as an Alternative to Hemagglutination Reaction of Influenza Viruses

As an alternative to the classical method of erythrocyte hemagglutination, a latex agglutination assay based on the interaction of influenza viruses with the sialoglycoprotein fetuin immobilized on the surface of polystyrene microspheres, has been developed. Twelve influenza A virus strains of different subtypes and two influenza B viruses of different lines were tested. Simultaneous titration of viruses using the classical hemagglutination test and the proposed latex agglutination assay showed similar sensitivity and a high degree of correlation (R = 0.94). The obtained microspheres can be used for titration of viruses that recognize and bind sialylated glycans as receptors. In particular, latex aggregation was also induced by the Newcastle disease virus.

Sandwich like poly(ionic liquid)s functionalized microspheres: Efficient interfacial catalysts for preparation of biodiesel

Smart photo-responsive nanospheres azo-p(St-TMGILs)-OEt with sandwich like structure were prepared by introducing alkaline ionic liquids (TMG ILs) and a pioneering photo-responsive monomer (azo-TEPIC) on the surface of polystyrene microspheres by one-pot soap-free emulsion polymerization with free radical polymerization. Then the as-prepared nanoparticles were used as interfacial catalysts for constructing Pickering emulsions, wherein, azo-TEPIC was first obtained by using organosilane to functionalize azobenzene. Pickering emulsions can be reversibly switched between emulsification and breakage by alternate exposure to UV and visible light. The Pickering emulsion was used for the transesterification of soybean oil and ethanol to produce biodiesel and was found to give yields above 97% under mild reaction conditions with superior cycling stability of the catalyst.

Latex Agglutination as an Alternative to the Hemagglutination Reaction of Influenza Viruses

As an alternative to the classical method of erythrocyte hemagglutination, a latex agglutination assay based on the interaction of influenza viruses with the sialoglycoprotein fetuin immobilized on the surface of polystyrene microspheres has been developed. Twelve influenza A virus strains of different subtypes and two influenza B viruses of different lines were tested. Simultaneous titration of viruses using the classical hemagglutination test and the proposed latex agglutination assay showed similar sensitivity and a high degree of correlation (R = 0.94). The obtained microspheres can be used for titration of viruses that recognize and bind sialylated glycans as receptors. In particular, latex aggregation was also induced by the Newcastle disease virus.

Preparation and characterization of a homogeneous immunoassay for point-of-care testing (POCT) of procalcitonin (PCT).

Procalcitonin (PCT) has been recognized as a specific and early marker for microbial infection and sepsis. Sensitive measuring interaction-triggered luminescence experiment (SMILE), a homogeneous immunoassay method, was established for point-of-care testing (POCT) of PCT. SMILE is achieved through the principle of double antibody sandwich, where two antibodies immobilized on the surface of polystyrene microspheres (donor and acceptor beads) bind to the PCT antigen. The donor bead contains phthalocyanine dye (luminol chemiluminescent substance) and the acceptor bead contains dimethylthiophene derivatives and Eu chelates. Therefore, singlet oxygen can be transferred when the distance between donor and acceptor beads is within 200 nm, generating detectable luminescent signals. Scanning electron microscopy (SEM) was used to detect the diameter and polymer dispersity index (PDI) of microspheres before and after binding with antibodies to characterize the immobilization of antibodies. The reaction conditions for antibody immobilization including pH, mass ratio and reaction time have also been optimized. The limit of quantitation (LOQ) of the SMILE method (0.01 ng mL-1) was lower than that of the LFI method (0.1 ng mL-1), the working range (0.01-500 ng mL-1) was wider than that of the LFI method (0.1-50 ng mL-1), and the assay time (10 min) was shorter than that of the LFI method (15 min). So, SMILE is more suitable for POCT of PCT compared with lateral flow immunochromatography (LFI), which is the most used measuring method, due to its advantages of simple operation, saving time, convenience, wide detection range, and high sensitivity and accuracy.

Tyramine signal amplification on polystyrene microspheres for highly sensitive quantification of Aflatoxin B1 in peanut samples

Aflatoxin B1 (AFB1) is the most toxic mycotoxin in contaminated food, which poses a serious threat to food safety and human health. Hence, a novel microparticle counting immunosensor was proposed for sensitive AFB1 detection mediated by polystyrene microspheres (PS) and tyramine signal amplification (TSA). Magnetic nanoparticles were used as immune carriers. Tyramine (Ty) molecules were decorated on the surface of PS (PS-Ty). In the presence of H2O2, horseradish peroxidase converted tyramine to a short-lived radical intermediate, thus forming stable covalent bonds between the immune carrier and PS-Ty. After magnetic separation, the coupled magnetic immune complexes act as the immune carrier to trigger changes in the number of unreacted PS-Ty. The proposed novel immunosensor was able to discriminate as low as 2 pg/mL of AFB1 and exhibited approximately a 13.8-fold increase in detection limit compared to the conventional enzyme-linked immunosorbent assay. Taking advantage of tyramine signal amplification and magnetic separation, the sensitivity of this sensor has been improved by 1–2 orders of magnitude. The TSA-based signal enhancement system significantly improved the performance of the immunosensor for trace detection of risk factors from complex food matrices.

Yersinia pestis Surface Antigens in Reception of Specific Bacteriophages.

The significance of Yersinia pestis surface antigens in adhesiveness to specific bacteriophages has been studied with the use of two methodological approaches. It was shown that Ail protein immobilized on the surface of polystyrene microspheres (but not in the solution), can bind both the Pokrovskaya phage and pseudotuberculous diagnostic phage. YapF autotransporter interacted with both phages in a water-soluble form, but YapF bound to polystyrene microspheres interacted only with the Pokrovskaya phage. An assumption was made that Ail and YapF proteins can be the primary receptors providing non-specific reversible binding to the phages used in this work.

Surface PEGylation of ionophore-based microspheres enables determination of serum sodium and potassium ion concentration under flow cytometry.

We present here an ionophore-based ion-selective optode (ISO) platform to detect potassium and sodium concentrations in serum through flow cytometry. The ion-selective microsensors were based on polyethylene glycol (PEG)-modified polystyrene (PS) microspheres (PEG-PS). Ratiometric response curves were observed using peak channel fluorescence intensities for K+ (10-6M to 0.1M) and Na+ (10-4M to 0.2M) with sufficient selectivity for clinical diagnosis. Due to the matrix effect, proteins such as albumin and immunoglobulin caused an obvious increase in response for serum sample determination. To solve this problem, 4-arm PEG chains were covalently attached onto the surface of PS microspheres through a two-step reaction, which improved the stability and combated pollution of microspheres. As a preliminary application, potassium and sodium concentrations in human serums were successfully determined by the PEG-PS microsensors through flow cytometry.

Amphiphilic copolymers grafted on monodisperse magnetic microspheres as an efficient adsorbent for the extraction of safrole in the plasma

Polystyrene (PS) microsphere is a kind of attractive extracting medium due to its high stability in different matrices and its particle size can be controlled. The attachment of amphiphilic copolymers to the PS microsphere surface can overcome the drawback of PS relevant to its hydrophobic nature and low wettability. In our previous work, the magnetic composite based on PS microsphere (5 µm) and poly (divinylbenzene-co-N-vinylpyrrolidone, DVB-co-NVP) shell was successfully fabricated and applied for the extraction of safrole in cola drinks. However, the large size and ease of sedimentation limited its application in the enrichment of safrole from blood samples. Considering the adjustability of PS microsphere size, we synthesized the porous PS microspheres with the uniform size of 3 µm and then functionalized with Fe3O4 nanoparticles and poly (DVB-co-NVP) layer in this work. Using the proposed material as extraction sorbent, a simple and fast magnetic solid phase extraction (MSPE) method coupled with HPLC was developed for quantification of safrole in the plasma. Under the optimized conditions, the response to safrole was linear in the range of 0.02–12 µg mL−1, and the limit of detection (LOD) was 0.006 µg mL−1. Satisfactory recoveries were obtained between 85.67% and 97.74% (spiked at 0.05, 0.2, 2 µg mL−1) and the relative standard deviations (RSDs) for the above spiked levels of the analyte were below 3.9% (n = 6). The adsorbent can be reused for 6 cycles without a significant loss of extraction capability.

Mesoporous Silica Nanosheets with Tunable Pore Lengths Supporting Metal Nanoparticles for Enhanced Hydrogenation Reactions

The channel lengths of mesoporous materials have a crucial impact on the catalytic performances of as-loaded active components. However, it remains a challenge to precisely tune the mesochannel length in a wide range from ≤50 nm to 200 nm. In this paper, we developed a top-down strategy, that is to say, crushing hollow microspheres, for preparing mesoporous silica nanosheets (MSSs) with perpendicular mesochannels and tunable thicknesses. Owing to the heterogeneous growth of the mesoporous silica layer on the surfaces of polystyrene microspheres (hard template), it was achieved to regulate the mesochannel length continuously in the range of 20–200 nm. The obtained materials were characterized by X-ray diffraction (XRD), nitrogen sorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of channel lengths on the catalytic activity of metal nanoparticles was then investigated in the selective hydrogenation reaction of nitroarenes. It was found that a short channel not only favored dispersing metal nanoparticles uniformly and then avoiding pore blocking, but also improved the accessibility of metal nanoparticles largely during reactions.

Synthesis of Positively Charged Polystyrene Microspheres for the Removal of Congo Red, Phosphate, and Chromium(VI).

Uniform positively charged polystyrene microspheres were synthesized and further examined as a new sorbent for water remediation. The structures of the resulting sorbent were characterized by field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, and 1H nuclear magnetic resonance spectroscopy. The adsorption performance of the sorbent was evaluated using three typical pollutants, namely, Congo red, phosphate, and Cr(VI). The adsorption isotherms were fitted by the Langmuir and Freundlich models, while the adsorption kinetics was analyzed by the pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations. The thermodynamic parameters of the adsorption process including changes of enthalpy, entropy and Gibbs free energy, and binding constant were obtained by isothermal titration calorimetry measurements. The effects of solution pH and competitive ions on the adsorption process were investigated. The adsorption isotherms could be better fitted by the Langmuir model, yielding maximum adsorption capacities of 18, 6.2, and 1.1 mg g–1 for the adsorption of Congo red, Cr(VI), and phosphate, respectively. The adsorption kinetics could be best described by the pseudo-second-order equation. The spent sorbent was regenerated by washing with 1 M KOH and showed outstanding long-term cyclic performance. The findings suggested that the positive charges at the surface of polystyrene microspheres could serve as effective sites for the immobilization of anionic pollutants in solutions owing to the electrostatic attraction.

Facile fabrication of raspberry-like polystyrene/ceria composite particles and their catalytic application

Herein we present a facile approach to the attachment of ceria nanoparticles (CeO2 NPs) onto polystyrene (PS) microspheres in a one-step process based on the decrease in total Gibbs free energy of colloidal system. This synthetic method has the advantage of eliminating the complex surface functionalizations or modifications of support microsphere, which are usually necessary in the established synthesis of polymer-supported CeO2 NPs. Scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetry have been employed to characterize the as-prepared PS/CeO2 composite particles. The size and amount of CeO2 NPs deposited on the surface of PS microspheres can be easily controlled by changing the concentration of Ce(NO3)3·6H2O and reaction temperature. Furthermore, the resultant PS/CeO2 composite particles are tested for catalytic degradation of methyl orange (MO) in the presence of hydrogen peroxide (H2O2). Significantly, these composite particles are proved to be an efficient catalyst for catalyzing the oxidation degradation of MO and also show good stability in a recyclable manner.

Ultrasensitive electrochemical detection of tumor cells based on multiple layer CdS quantum dots-functionalized polystyrene microspheres and graphene oxide – polyaniline composite

In this work, a novel ultrasensitive electrochemical biosensor was developed for the detection of K562 cell by a signal amplification strategy based on multiple layer CdS QDs functionalized polystyrene microspheres(PS) as bioprobe and graphene oxide(GO) -polyaniline(PANI) composite as modified materials of capture electrode. Due to electrostatic force of different charge, CdS QDs were decorated on the surface of PS by PDDA (poly(diallyldimethyl-ammonium chloride)) through a layer-by-layer(LBL) assemble technology, in which the structure of multiple layer CdS QDs increased the detection signal intensity. Moreover, GO-PANI composite not only enhanced the electron transfer rate, but also increased tumor cells load ratio. The resulting electrochemical biosensor was used to detect K562 cells with a lower detection limit of 3 cellsmL−1 (S/N = 3) and a wider linear range from 10 to 1.0 × 107 cellsmL−1. This sensor was also used for mannosyl groups on HeLa cells and Hct116 cells, which showed high specificity and sensitivity. This signal amplification strategy would provide a novel approach for detection, diagnosis and treatment for tumor cells.

Facile fabrication of polystyrene microsphere supported gold-palladium alloy nanoparticles with superior catalytic performance for the reduction of 4-nitrophenol in water

Herein a simple method is reported for depositing gold-palladium alloy nanoparticles (NPs) with various chemical compositions on the surface of polystyrene microspheres (abbreviated as PS/Au-Pd composite particles) based on a thermodynamic effect. Noticeably, surface pretreatments of PS microspheres and Au-Pd alloy NPs are not required at all for achieving the self-assembly of preformed heterogeneous particles. The Au-Pd alloy NPs act as steric stabilizer and attach spontaneously onto the surface of the PS microspheres to reduce the Gibbs free energy of the colloidal system. Afterwards, we investigate the catalytic properties of PS/Au-Pd composite particles for the reduction of 4-nitrophenol, which is of industrial significance for converting 4-nitrophenol (a water pollutant with high toxicity) into 4-aminophenol (an important intermediate of various industries). We have found that the catalytic activity of PS/Au-Pd composite particles is remarkably affected by the chemical composition of supported Au-Pd alloy NPs. The maximum activity is achieved in the case of supported alloy NPs having the Au/Pd molar ratio of 54:46, which is much higher than that of pure Au NPs and Pd NPs supported on the PS microspheres. Furthermore, these PS/Au-Pd composite particles can be easily recovered owing to the large size of PS microspheres and reused three times without significant loss of catalytic activity.

Investigation on Formation Mechanism of Magnetic Nanoparticles-coated on Polystyrene Microspheres in Aqueous Solution of Anhydrous Ethylenediamine and Hexamethylene Tetramine

The monodispersed polystyrene (PS) microspheres were modified by concentrated sulfuric acid to obtain PS microspheres with negative charges, and then polystyrene/magnetic composite microspheres were fabricated by a simple and novel method in aqueous solution of anhydrous Ethylene diamine (EDA) and Hexamethylenetetramine (HMTA). Through serials of contrast experiments (based on different precursor ratios) and characteristic investigations of target samples, we have discovered the functions of EDA and HMTA, respectively. EDA not only acted as a weak base providing OH- ions, but also acted as a chelating combining with Fe2+ ions, which could control the concentration of Fe2+ ions, and resulted in the pure Fe3O4 nanoparticle coated on the surface of PS microspheres. Otherwise, the typical XRD peaks of FeOOH and Fe3O4 appeared, simultaneously, if HMTA played an action in the formation magnetic nanoparticles-coated PS microspheres. It indicated that HMTA could provide OH- ions and make Fe2+ to become FeOOH and Fe3O4, simultaneously, which could be confirmed the reaction mechanism suggested by us. Finally, the corresponding possible reaction mechanisms of EDA and HMTA for fabricating magnetic composite microspheres have been suggested in detail by combining SEM, XRD, FTIR analysis together.

Preparation and photothermal study of polystyrene coated with gold nanoshell composite particles

Polystyrene coated with gold nanoshell composite particles, with good photothermal properties, were prepared by electrostatic self-assembly. Firstly, polystyrene (PS) microspheres were synthesized by emulsifier-free emulsion polymerization, and it is determined that the PS microsphere has an average diameter of 165 nm, carboxyl on the surface, and its surface potential turned into +38.3 mV after modified by polyallylamine hydrochloride (PAH). Secondly, gold seeds, with an average diameter of 5.14 nm and surface potential of −10.7 mV, were prepared via sodium borohydride reducing chloroauric acid. Then, gold seeds were adsorbed on the surface of PS microspheres by electrostatic self-assembly and the composite particles were obtained after gold seeds grew multiple times. Finally, 0.3 mg/mL composite particles dispersion was irradiated with a near-infrared (NIR) light source and the temperature of the dispersion increased 13 °C after 5 min.

Silver nanoparticles embedded in polystyrene-polyvinyl pyrrolidone nanocomposites using γ-ray irradiation: Physico-chemical properties

γ-Ray irradiation is used for the synthesis of silver–Polystyrene polyvinyl pyrrolidone nanocomposite microspheres with a controlled shape, size, and functional properties. A monodispersed polystyrene microsphere was synthesized using dispersion polymerization induced by γ-ray irradiation. A polystyrene microsphere surface was used to attract Silver (Ag) nanoparticles in which it is created on it via the continuous reduction of Ag+ by γ-ray irradiation. Transmission Electron Microscopy, X-ray Diffraction Analysis, Ultraviolet–Visible Absorption, Thermal Gravimetric Analysis and Fourier Transform Infrared Spectroscopy are used for characterization of the final product. The discussion focuses on the physical–chemical aspects of the method. Special attention is paid to the preparation of nanocomposites with individual (non-aggregated) nanoparticles with a narrow size distribution and versatile morphologies, including the design of nanoparticles and nanocomposites that can perform multifunctional purposes. The focus was also on the problem of the spatial arrangement of nanoparticles and the elucidation of the role of polymers using this method. The synergistic role of the ingredients on the performance of nanocomposites was also discussed.

Facile synthesis of gold nanoparticle-coated polystyrene composite particles templated from Pickering emulsion

Abstract Herein we develop a facile and controllable strategy for the preparation of composite particles composed of polystyrene (PS) microspheres decorated with gold nanoparticles (AuNPs) through Pickering emulsion template. The oil-in-water Pickering emulsion is prepared using unmodified citrate-stabilized AuNPs and toluene solution of unfunctionalized PS as stabilizer and dispersion phase, respectively. After the evaporation of toluene from the Pickering emulsion, the AuNP-coated PS composite particles are obtained. The resultant AuNP-coated PS composite particles have been characterized extensively by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. Significantly, our method enables easy and effective control over the size and surface coverage of AuNPs on the surface of PS microspheres. Furthermore, the proposed method does not only allow the easy deposition of other noble metal (Ag, Pt, and Pd) nanoparticles onto the surface of PS microspheres but also can be directly applicable to the employed PS polymers derived from different approaches. In addition, the AuNP-coated PS composite particles as an example exhibited excellent catalytic activity and recyclability in the reduction of rhodamine B by NaBH4.