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PubMed2005

Multiple headspace single-drop microextraction-a new technique for quantitative determination of styrene in polystyrene.

Single-drop microextraction (SDME), an emerging miniaturised extraction technique, was for the first time combined with multiple headspace extraction (MHE) to enable the quantitative determination of volatiles in solid matrixes by SDME technique. The concept of multiple headspace single-drop microextraction (MHS-SDME) was then applied for quantitative determination of styrene in polystyrene (PS) samples. Good linearity for the multiple headspace extraction was obtained when the migration of styrene was facilitated by grinding the samples and incubating them for 1 h at 150 degrees C prior the first extraction. Two microlitres of butyl acetate was used as the single-drop microextraction solvent and the extraction time was 5 min per cycle. The relative standard deviation (RSD) for single-drop microextraction of styrene standard at n=6 was 7.6%. Linearity was shown for styrene concentrations between 0.005 and 0.75 microg/ml (R2=0.999). This corresponds to total amount of styrene between 0.1 and 15 microg. The limit of quantitation for styrene standard at S/N 10 was 0.005 microg/ml. The developed method was validated against and showed good agreement with an earlier reported dissolution-precipitation method.

Gas Chromatography-Mass Spectrometry↗

PubMed2005

Separation of branched polystyrene by comprehensive two-dimensional liquid chromatography.

Branched polystyrenes (PS) featuring a bivariate distribution in the molecular weight and in the number of branches were characterized by comprehensive two-dimensional liquid chromatography (2D-LC). The branched PS were prepared by anionic polymerization using n-butyl Li as an initiator and a subsequent linking reaction with p-(chlorodimethylsilyl)styrene (CDMSS). The n-butyl Li initiator yields polystyryl anions with broad molecular weight distribution (MWD) and the linking reaction with CDMSS yields branched PS with different number of branches. For the first dimension (1st-D) separation, reversed-phase temperature gradient interaction chromatography (RP-TGIC) was employed to separate the branched polymer according to mainly the molecular weight. In the second dimension (2nd-D) separation, the effluents from the RP-TGIC separation are subjected to liquid chromatography at chromatographic critical conditions (LCCC), in which the separation was carried out at the critical condition of linear homo-PS to separate the branched PS in terms of the number of branches. The 2D-LC resolution of RP-TGICxLCCC combination worked better than the common LCCCxsize-exclusion chromatography (SEC) configuration due to the higher resolution of RP-TGIC in molecular weight than SEC. Furthermore, by virtue of using the same eluent in RP-TGIC and LCCC (only the column temperature is different), RP-TGICxLCCC separation is free from possible 'break through' and large system peak problems. This type of 2D-LC separation could be utilized efficiently for the analysis of branched polymers with branching units distinguishable by LC separation.

Chromatography, Liquid↗

PubMed2006

Unusual retention behaviour of 4-substituted piperidines on polybutadiene and polystyrene coated zirconia by comparison to reverse phase silica.

The retention properties of a range of N-methylated and N-des-methyl 4-substituted piperidines on polybutadiene (PBD) and polystyrene (PS) coated zirconia have been studied and compared to those of Xterra RP(18) and Genesis C(18) silica. The effect of buffer type and pH are investigated with regard to the elution order on all three stationary phases. The change in the elution order is linked to the degree of substitution of the piperidine nitrogen and appears to be independent of the rest of the structure, indicating that this moiety is most heavily involved in the separation mechanism on the zirconia phases.

Buffers↗

PubMed2005

Orientation and confinement of cells on chemically patterned polystyrene surfaces.

UV/ozone oxidation was combined with a photomasking technique to produce adjacent regions of different chemistry on polystyrene (PS) surfaces. The surface chemistry and topography were studied using AFM, XPS and contact angle measurements. The physicochemical patterns were visualised by the condensation of water vapour upon the surfaces and by the differential attachment of Chinese hamster ovarian (CHO) cells. The orientation of CHO cells on 55 and 125 microm wide oxidised PS strips were measured and found to be highly dependent on the width of the oxidised feature. CHO cells in relatively close proximity to a linear polar/non-polar border showed significant axial alignment along the border. CHO cells can also be confined to specific regions of the polymer surface. Cells attached to larger areas (75 microm x 75 microm) were found to have a smaller average cell size than cells attached to the smaller (56 microm x 56 microm) areas.

Animals↗

PubMed2005

Micropatterning of polystyrene nanoparticles and its bioapplications.

Micropatterning of biomolecules forms the basis of cell culture, biosensor and microarray technology. Currently, the most widely used techniques are photoresist lithography, soft lithography or using robots which all involve multi-step surface modification directly on a planar substrate. Here we report a method to pattern biomolecules through self-assembling polystyrene nanoparticles in arrayed microwells on a solid surface to form well-ordered patterning, followed by attaching biomolecules to the assembled nanoparticles. The formation of colloidal patterns depends on capillary force, surface wettability and physical confinement. This method can be used for micropatterning a variety of biomolecules such as protein and antibody.

Colloids↗

PubMed2006

Immobilization and enzymatic activity of glucose oxidase on polystyrene surface modified with ozone aeration and UV irradiation in distilled water and/or aqueous ammonia solution.

Adsorption condition and enzymatic activity of glucose oxidase (GOD) on polystyrene (PS) film surfaces modified with ozone aeration and UV irradiation (O3/UV) treatment were investigated. The total amount of GOD immobilized on the PS film modified with the O3/UV treatment in distilled water (PS-W film) was approximately twice as large as that on the film treated in an aqueous ammonia solution (PS-A film), whereas the specific activity of GOD on the PS-A film was four times higher than that on the PS-W film. In contrast, no enzymatic activity of GOD on the non-treated PS film was observed because of irreversible denaturation of the adsorbed GOD. We therefore conclude that the PS films modified by the O3/UV treatment in the aqueous media are effective in immobilizing GOD.

Adsorption↗

PubMed2004

Single and multiple exposure tolerance study of polystyrene sulfonate gel: a phase I safety and colposcopy study.

OBJECTIVES: To evaluate symptoms and signs of genital irritation, vaginal leakage and acceptability of polystyrene sulfonate (PSS), which is being studied as a vaginal contraceptive and microbicide. METHODS: Forty-nine women applied 2.5 mL of either 5% PSS, 10% PSS, PSS vehicle, or Conceptrol (a marketed spermicidal product containing 4% nonoxynol-9) for 6 consecutive days. RESULTS: All women completed the study except one in the Conceptrol group who experienced vaginal symptoms after her first use and was discontinued. After both the first use and after all uses, irritation was seen among more women in the Conceptrol group than in the PSS groups, reaching statistical significance with regard to any evidence of irritation, signs of irritation and product-related irritation. There were no adverse events that were serious, unexpected and related to product use in any group. The 5% concentration of PSS may be preferable in terms of leakage and acceptability. CONCLUSION: The results suggest that PSS has a safety profile comparable to that of the marketed nonoxynol-9 product, Conceptrol, and appears to be associated with less genital irritation.

Adolescent↗

PubMed2005

DNA array analysis of Candida albicans gene expression in response to adherence to polystyrene.

Candidiasis is often initiated by the colonization of inert surfaces. In order to elucidate the mechanisms involved in this adherence process, DNA macroarrays were used to analyze the transcriptome of Candida albicans, the main causative agent of this mycoses, in a simple adherence model using germ tubes produced in polystyrene Petri dishes. Non-adherent germ tubes produced on glass surface were used as a control. Analysis of gene expression displayed 77 genes identified as statistically overexpressed in adherent germ tubes. Among these genes, some encoded enzymes participating in metabolism of lipids (such as LIP6), of proteins (such as SAP1) or of carbohydrates (like PGI1, PMI40 and PSA1. Some of these genes have already been reported as playing a role in pathogenesis of C. albicans. However, functions were unknown for a large part (45.5%) of the overexpressed genes which will be analyzed further in order to define their relationship with adherence.

Candida albicans↗

PubMed2006

In vitro effects of micafungin against Candida biofilms on polystyrene and central venous catheter sections.

Long-term inserted and surgically implanted catheters can be colonised by Candida spp. Candida biofilms in vitro are often resistant to antifungal agents. The aim of this study was to investigate the in vitro activity of micafungin (MFG) against six Candida spp. biofilms on polystyrene (PS) and central venous catheter (CVC) sections. Safranin staining and differential interference contrast microscopy were used to demonstrate biofilm production. MFG activity was determined by the reduction in metabolic activity (%RMA) by tetrazolium reduction assay on both substrates. In vitro, Candida albicans, Candida parapsilosis, Candida glabrata, Candida tropicalis, Candida dubliniensis and Candida kefyr produced mature biofilms on PS and CVC sections. MFG was active against C. kefyr (0.5 microg/mL) and C. glabrata (<0.5 microg/mL) on PS. However, MFG displayed resistance (>16 microg/mL) against C. albicans, C. dubliniensis,C. tropicalis and C. parapsilosis. On CVC disks, MFG was active against C. glabrata (1 microg/mL) as well as C. parapsilosis and C. albicans (<0.5 microg/mL). MFG was resistant (>16 microg/mL) against C. dubliniensis, C. tropicalis and C. kefyr. MFG was active in vitro against all six Candida spp. on both substrates. However, MFG could not reduce the metabolic activity completely even at the highest concentration.

AIDS-Related Opportunistic Infections↗

PubMed2005

Calorimetric study of bovine serum albumin dilution and adsorption onto polystyrene particles.

Titration calorimetry was used to investigate the interaction between a model antigen, bovine serum albumin (BSA), and a model particulate carrier, polystyrene (PS). The binding enthalpy was much higher than reported in the literature for a similar system and did not display a sigmoidal binding curve. These experiments may have accessed low coverage surface sites due to the irreversible nature of protein binding and stepwise titration. An important correction is the heat of dilution of the protein solution. Two regimes were observed: at low concentrations of BSA (below ca. 0.3% (w/v)) an exothermic dilution enthalpy of ca. -100 mJ mg-1 was determined, whereas at higher concentrations of BSA values of ca. -20 mJ mg-1 were obtained. Solution rheological data also showed a change at 0.3% (w/v) BSA, so we hypothesise that the fraction of the BSA as monomers, dimers and polymers in solution changes at approximately 0.3% (w/v).

Adsorption↗

PubMed2006

Development of a one-step ELISA method using an affinity peptide tag specific to a hydrophilic polystyrene surface.

Glutathione S-transferase genetically fused with an affinity peptide tag, PS19 (RAFIASRRIKRP) having a specific affinity for a hydrophilic polystyrene (PS) surface, was preferentially immobilized on a hydrophilic PS (phi-PS) plate without suffering from interference by coexisting protein molecules. Furthermore, rabbit IgG chemically conjugated with a peptide, KPS19R10, in which (10)Lys in PS19 was replaced with Arg and one Lys residue was added at the N-terminus as a coupling site for glutaraldehyde, showed a higher immobilization affinity to the phi-PS plate than that conjugated with the PS19 peptide. On the basis of these findings, the use of a phi-PS plate and peptide tag-linked ligand proteins permitted a one-step or two-step enzyme-linked immunosorbent assay (ELISA) to be achieved, resulting in a substantial reduction in operational time compared with the conventional ELISA method using a hydrophobic PS (pho-PS) plate, while maintaining a high sensitivity. Furthermore, the sensitivity was increased to a greater extent compared to the conventional ELISA meihod when the one-step ELISA was applied to the detection of bovine insulin in a sandwich mode, due to the reduced number of washing and incubation steps. The method proposed here would be a versatile method for use in various ELISA techniques such as sandwich and competitive ELISAs using an antigen, an antibody and streptavidin that are genetically fused or chemically conjugated with the PS-specific affinity peptide as the ligand protein.

Affinity Labels↗

PubMed2004

Preparation of silica-polystyrene core-shell particles up to micron sizes.

A method for producing silica-core composite particles with a polystyrene shell is proposed. Silica particles were prepared by the Stöber method through condensation and hydrolysis of tetraethyl orthosilicate in a water-ethanol-ammonia solution. The silica particles were the surface-modified with a coupling reagent, methacryloxypropyltrimethoxysilane (MPTMS), to introduce vinyl groups onto the particle surfaces. Polymerization of styrene was conducted with an initiator, potassium persulfate (KPS), and an anionic monomer, sodium p-styrenesulfonate (NaSS), in the presence of the silica particles. In these coating experiments, the average size of the silica particles was varied from 339 to 1210 nm with the concentration ranges of MPTMS (0-10 mmol/l), NaSS (0-10 mmol/l), KPS (4-12 mmol/l), and styrene (0.12-0.4 mol/l). Selection of reaction conditions enabled the preparation of composite particles that contained one core of silica. The coefficient of variance of size distribution of the composite particles was less than 7%, and shell thickness was in the range 125 to 410 nm.

Particle Size↗

PubMed2005

Adsorption of different amphiphilic molecules onto polystyrene latices.

In order to know the influence of the surface characteristics and the chain properties on the adsorption of amphiphilic molecules onto polystyrene latex, a set of experiments to study the adsorption of ionic surfactants, nonionic surfactants and an amphiphilic synthetic peptide on different latex dispersions was performed. The adsorbed amount versus the equilibrium surfactant concentration was determined. The main adsorption mechanism was the hydrophobic attraction between the nonpolar tail of the molecule and the hydrophobic regions of the latex surface. This attraction overcame the electrostatic repulsion between chains and latex surface with identical charge sign. However, the electrostatic interactions chain-surface and chain-chain also played a role. General patterns for the adsorption of ionic chains on charged latex surfaces could be established. Regarding the shape, the isotherms presented different plateaus corresponding to electrostatic effects and conformational changes. The surfactant size also affects the adsorption results: the higher the hydrophilic moiety in the surfactant molecule the lower the adsorbed amount.

Adsorption↗

PubMed2005

Shifts in polystyrene particle surface charge upon adsorption of the Pluronic F108 surfactant.

Electrical field-flow fractionation (ElFFF) and sedimentation field-flow fractionation (SdFFF) were used in combination to study the adsorption of the triblock polymeric surfactant, Pluronic F108 [(EO)129-(PO)56-(EO)129] to 200 nm polystyrene (PS) latex spheres. The SdFFF technique allowed an accurate determination of the mass of surfactant adsorbed on each particle from a solution of given concentration. To complement this isotherm study, we show that ElFFF can be used to measure fractional coverages of the formed electrically neutral surfactant layers on the charged PS particles. Through a combination of the two techniques it is possible to gain information about the structure of the adsorbate layer. Thus, when Pluronic F108 is taken up by the PS surface from solutions of low concentration, all three blocks appear to adhere to the surface as long as there is free space available. As the solution concentration increases and the fractional coverage reaches approximately 20%, the surface turns crowded enough to let the strongly adsorbing PPO blocks competitively displace the weakly adherent PEO blocks, which gradually rise to extend into the aqueous phase until the surface is fully saturated.

Adsorption↗

PubMed2006

Morphology of hybrid polystyrene-block-poly(ethylene oxide) micelles: analytical ultracentrifugation and SANS studies.

Morphology and structure of aqueous block copolymer solutions based on polystyrene-block-poly(ethylene oxide) (PS-b-PEO) of two different compositions, a cationic surfactant, cetyl pyridinium chloride (CPC), and either platinic acid (H2PtCl6.6H2O) or Pt nanoparticles were studied using a combination of analytical ultracentrifugation (AUC), transmission electron microscopy (TEM), and small angle neutron scattering (SANS). These studies combining methods contributing supplemental and analogous structural information allowed us to comprehensively characterize the complex hybrid systems and to discover an isotope effect when H2O was replaced with D2O. In particular, TEM shows formation of both micelles and larger aggregates after incorporation of platinic acid, yet the amount of aggregates depends on the H2PtCl6.6H2O concentration. AUC reveals the presence of micelles and micellar clusters in the PS-b-PEO block copolymers solution and even larger (supermicellar) aggregates in hybrids (with CPC). Conversely, SANS applied to D2O solutions of the similar species indicates that micelles are spherical and no other micellar species are found in block copolymer solutions. To reconcile the SANS and AUC data, we carried out AUC examination of the corresponding D2O block copolymer solutions. These measurements demonstrate a pronounced isotope effect on micelle aggregation and micelle size, i.e., no micelle aggregation in D2O solutions, revealing good agreement of AUC and SANS data.

Calorimetry, Differential Scanning↗

PubMed2004

Pre-coating with serum albumin reduces receptor-mediated hepatic disposition of polystyrene nanosphere: implications for rational design of nanoparticles.

We evaluated the in vivo disposition characteristics of polystyrene nanospheres (NS) with the particle size of 50 nm (NS-50) pre-coated with human serum albumin (HSA) after intravenous administration in rats. HSA-coated NS-50 showed much longer blood-circulating property and the hepatic uptake clearance for HSA-coated NS-50 was about 1/5 of that for NS-50. In parallel with the results obtained in the in vivo study, liver perfusion experiments also showed that the hepatic disposition of HSA-coated NS-50 was much less than that of NS-50 in the presence of serum in the perfusate. To unravel the mechanism behind the less affinity of HSA-coated NS-50 to the liver, serum proteins associated on the surface was quantitatively and qualitatively assessed. The results indicated that pre-coated HSA impaired subsequent association of serum proteins onto the surface, suggesting that the association of a given serum protein with opsonic activity might be suppressed by HSA pre-coating. From these findings, pre-coating of nanoparticles with serum albumin could be useful to prevent their rapid clearance by mononuclear phagocyte system in vivo.

Animals↗

PubMed2005

Incorporation of low molecular weight biocides into polystyrene-divinyl benzene beads with controlled release characteristics.

Triclosan and phosphonium salt biocides have been separately incorporated into polystyrene-divinylbenzene (PS-DVB) beads by suspension polymerization. Ultraviolet (UV) absorption measurements have been used to monitor the release of these low molecular weight biocides out of the PS-DVB beads immersed in water-ethanol mixtures and in physiological saline. The release of the biocide agents is strongly dependent on either the DVB or/and the antimicrobial composition ratio in the beads. An increase of biocide incorporation in the PS/DVB beads was accompanied by a corresponding enhancement of its concentration in liquid mixtures. On the contrary, higher cross-linking densities hindered the biocide migration out of the beads by diminishing its release rate into either the aqueous ethanol solutions or the natural serum. Moreover, Fourier transform Raman (FT-Raman) spectra and Attenuated Total Reflectance Infrared (ATR-FTIR) measurements of the PS-DVB-Triclosan and PS-DVB-phosphonium salt beads, before and after their immersion in water-ethanol solutions, gave a similar qualitative evidence of the biocide release.

Anti-Infective Agents, Local↗

PubMed2026

Polystyrene microplastics induce auditory neurotoxicity in mammals: Integrated multi-omics profiling reveals oxidative damage and synaptic molecular dysregulation.

Microplastics (MPs) are ubiquitous environmental pollutants, yet their neurotoxic effects on the auditory system remain poorly understood. This study develops an integrated multi-level analytical framework combining auditory neurophysiology, behavioral assessment, tissue biochemistry, transcriptomics, and proteomics to investigate polystyrene (PS)-MPs-induced auditory neurotoxicity in rats. PS-MPs infiltrate the auditory system and significantly impair auditory processing, with central dysfunction emerging earlier and more prominently than peripheral alterations. Multi-omics analyses reveal coordinated suppression of glutamatergic synapse and Wnt signaling pathways in the cochlear nucleus. Mechanistically, PS-MPs perturb the crosstalk between glutamatergic synaptic and Wnt signaling, promoting AMPA receptor (AMPAR) internalization and potentially affecting synaptic plasticity-related processes and neuronal responsiveness. In parallel, PS-MPs trigger oxidative stress, apoptosis, and glial activation, reflecting pronounced neuroinflammatory and redox imbalance. In primary cochlear nucleus neurons (PCNNs), these mechanisms were further validated in vitro, where activation of Wnt signaling by Wnt3a significantly alleviated oxidative injury and reduced AMPAR internalization. Collectively, these findings provide comprehensive preclinical evidence for the neurotoxic potential of MPs and reveal a previously unrecognized PS-MPs-induced auditory neurotoxicity, although further studies are needed for human relevance. Results from the rat model further implicate Wnt-mediated signaling as a potential modulatory pathway underlying MPs-induced synaptic molecular alterations and redox dysfunction.

Animals↗