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PubMed2006

Electrokinetic transport of a spherical gel-layer model particle: inclusion of charge regulation and application to polystyrene sulfonate.

An electrokinetic gel-layer model of a spherical, highly charged colloid particle developed previously [S. Allison, J. Colloid Interface Sci. 277 (2004) 248], is extended in several ways. The charge of the particle is assumed to arise from deprotonation of acidic groups that are present, in uniform concentration, over a portion (or all) of the gel layer. Free energy considerations coupled with Poisson-Boltzmann theory are used to estimate how the local electrostatic environment of a charged gel layer alters the local pK(a) of the acidic groups. This modulation of the charge of the colloidal particle, or "charge regulation," can be significant even for colloidal particles with strongly acidic groups at moderate pH if the ambient salt concentration is low. The methodology is applied to the viscosity and electrophoretic mobility data of a particular polystyrene sulfonate latex over a broad range of monovalent salt (NaCl) concentration [M.J. Garcia-Salinas, F.J. de las Nieves, Langmuir 16 (2000) 715]. The experimental data can be accounted for by a gel layer model that decreases in thickness, but does not vanish, as the salt concentration is increased. Viscosity data provides valuable information about the degree of solvation of the colloidal particle and the thickness of the gel layer. The mobility data is best explained by a model in which only the outermost portion of the gel layer is charged. Charge regulation is significant at a monovalent salt concentration of 3 x 10(-3) mol/l and increases as the salt concentration decreases.

Journal Article↗
PubMed2006

Kinetics of polyelectrolyte adsorption onto polystyrene latex particle studied using electrophoresis: effects of molecular weight and ionic strength.

The kinetics of the adsorption of a cationic polymer flocculant onto negatively charged polystyrene latex (PSL) particles were measured by means of electrophoresis as a function of the molecular weight of the polyelectrolyte and the ionic strength of the solution. In the experiment, the dispersion of bare PSL particles was mixed with a polyelectrolyte solution by means of end-over-end rotation in which the mixing intensity was evaluated in terms of the collision frequency between the colloidal particles. The rate of electrophoretic mobility of a PSL particle, which remained as a singlet, was measured against the mixing steps, which was equivalent to the time elapsed after the onset of flocculation. The shape of the kinetic curves is typical: a linear increase for a short period followed by a plateau, implying the saturation of the colloidal surface by the adsorbed polyelectrolyte. In the case of low ionic strength, the plateau value was dependent on the molecular weight of the polyelectrolyte. That is, a lower plateau value was detected when the molecular weight of the polyelectrolyte was smaller and its concentration was lower. However, the amount of adsorption was kinetically controlled only for the case of higher molecular weight. In the case of high ionic strength, the plateau value of electrophoresis was constant, regardless of the polyelectrolyte concentration and molecular weight. These data will ultimately be useful in further analysis of the flocculation behavior of colloidal particles with a polyelectrolyte.

Journal Article↗
PubMed2006

In situ synthesis of sulfide-coated polystyrene composites for the fabrication of photonic crystals.

Sulfide (CdS, ZnS, and SnS(2))-coated polystyrene (PS) nanocomposites with a diameter of about 160 nm were synthesized by an in situ synthesis method. The PS spheres adsorbed polyelectrolytes, which were coordinated with Cd(2+) and Zn(2+) reacted with sulfions released through the hydrolysis of thioacetamide in an aqueous bath. As to the SnS(2)-coated PS composite, we introduced a deposition method in which a thin layer of SnS(2) was deposited on the surface of PS spheres. The PS spheres assembled on the patterned substrate of porous aluminum oxide (PAO) were more regular than those on the nonpatterned microslide, so the PS spheres coated with CdS and ZnS composites were assembled into ordered arrays on the PAO substrate, respectively. And the obtained lambda(max) of CdS-coated PS colloid crystal array red-shifted 262 nm compared with that of the pure PS colloid crystal array. All the particles and colloid crystal arrays were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Energy-dispersive X-ray (EDX) was undertaken to determine the elements Cd, S, and Sn.

Journal Article↗
PubMed2026

Paternal exposure to polystyrene nanoplastics induces inter- and transgenerational bronchopulmonary dysplasia-like damage in male offspring by FtMt hypermethylation-mediated ferroptosis.

Bronchopulmonary dysplasia (BPD) is a major cause of chronic lung disease in both preterm infants and adults, but its etiology remains incompletely understood. In this study, F0 generation mice were exposed to polystyrene nanoplastics (PS-NPs), and F1 to F3 generations were obtained by breeding. Multi-omics sequencing including whole genome methylation sequencing, single cell transcriptome sequencing and transcriptome sequencing was performed on the lungs of offspring. The levels of Fe2+, lipid peroxidation products and key gene expression were determined. Male mice exposed to PS-NPs at environmentally relevant doses produced offspring (F1 and F2) that exhibited a typical BPD-like phenotype. Meanwhile, the F0 males showed diminished sperm motility, demonstrating that paternal PS-NPs exposure constituted an etiological factor for BPD in descendants. Mechanistic studies showed that PS-NPs exposure upregulated the expression of DNA methyltransferase Dnmt3a, leading to global hypermethylation of the sperm genome. Importantly, the hypermethylated promoter signature of the mitochondrial ferritin (FtMt) gene partially resisted epigenetic reprogramming and was transmitted to the lungs of offspring, resulting in persistently low FtMt expression in F1 and F2 lungs. This led to increased intracellular Fe2+ levels, subsequently triggered ferroptosis in alveolar epithelial cells, and ultimately impaired alveolarization. Knockdown of FtMt confirmed that FtMt deficiency was sufficient to induce ferroptosis and BPD-like lung injury both in vitro and in vivo. Furthermore, using in vitro fertilization of F0 sperm combined with Dnmt3a siRNA microinjection, we directly demonstrated that Dnmt3a is a key driver for FtMt to escape reprogramming and maintain its hypermethylation. In summary, this study reveals for the first time that paternal PS-NPs exposure causes BPD through a Dnmt3a-FtMt hypermethylation intergenerational and transgenerational axis, providing an epigenetic basis for understanding paternal derived chronic lung disease and potential targets for early intervention.

Animals↗
PubMed2004

As(V) retention and As(III) simultaneous oxidation and removal on a MnO2-loaded polystyrene resin.

Based on KMnO4 oxidative capacity, a polystyrene matrix loaded with manganese dioxide was synthesized from an anionic commercial resin in chloride form. This medium, called R-MnO2, was tested for As(V) retention and for As(III) simultaneous oxidation and removal. Equilibrium was reached in 2 h and isotherms showed that R-MnO2 maximal capacities towards As(III) and As(V) are, respectively, 0.7 and 0.3 mmol/g. Various mechanisms were involved in As(III) retention: oxidation of H3AsO3(0) by MnO2(s) leading to the formation of HAsO4(2)- and Mn2+, fixation of As(V) formed on the resin beads and precipitation of Mn3(AsO4)2 with Mn2+ released. Successive arsenic desorption and retention steps were performed and showed that the quantity desorbed was low compared to the quantity removed during the first stage of the process. A second removal step, carried out under the same conditions as the first one, proved that the matrix second-removal capacity was weak. This solid sorbent, although not reusable, can be considered in field application as arsenic retention is really strong.

Journal Article↗
PubMed2005

Visualization of single-wall carbon nanotube (SWNT) networks in conductive polystyrene nanocomposites by charge contrast imaging.

The morphology of conductive nanocomposites consisting of low concentration of single-wall carbon nanotubes (SWNT) and polystyrene (PS) has been studied using atomic force microscopy (AFM), transmission electron microscopy (TEM) and, in particular, scanning electron microscopy (SEM). Application of charge contrast imaging in SEM allows visualization of the overall SWNT dispersion within the polymer matrix as well as the identification of individual or bundled SWNTs at high resolution. The contrast mechanism involved will be discussed. In conductive nanocomposites the SWNTs are homogeneously dispersed within the polymer matrix and form a network. Beside fairly straight SWNTs, strongly bended SWNTs have been observed. However, for samples with SWNT concentrations below the percolation threshold, the common overall charging behavior of an insulating material is observed preventing the detailed morphological investigation of the sample.

Journal Article↗
PubMed1980

Reversed-phase liquid chromatography of aromatic nitro compounds on a macroporous polystyrene gel.

The retention behaviour of some nitrobenzene derivatives was studied by reversed-phase chromatography on the macroporous polystyrene gel Separon SE with methanol-water, acetonitrile-water, tetrahydrofuran-water and methanol-water with adjusted pH as the eluents. The effect of the mobile phase and the presence of additional polar and non-polar substituents in the molecule of the solute on the retention were investigated. Using methanol-water (80:20) the contribution of the nitro group to the retention of the molecule is positive for substances containing both polar and non-polar functional groups. The contribution of the nitro group did not change if a mobile phase with adjusted pH was used. With acetonitrile-water and tetrahydrofuran-water the situation was more complicated.

Chromatography, Liquid↗
PubMed1980

Peptide separations on substituted polystyrene resins. Effect of cross-linkage.

The effect of copolymer cross-linkage on the resolution of soluble tryptic peptides of human globin (alpha- and beta-chains) separated in columns containing substituted polystyrene resin classified to 11 +/- 1 micrometer has been examined. With both the cation and anion exchange resins, polymers of lower cross-linkage provided better resolution; inferior resolution was obtained with 12% cross-linked resins. It was also observed that microparticle anion-exchange resins could be used in columns maintained at 55 degrees instead of 35 degrees as used traditionally. Resolution and yield with 20 x 1 cm resin beds were generally as good as or superior to much longer columns of crushed bead resin of the same chemical structure.

Anion Exchange Resins↗
PubMed2003

Synthesis of cross-linked core-shell polymer particles by free-radical dispersion copolymerization of 4-vinylpyridine with polystyrene macromonomers in nonaqueous media.

Cross-linked core-shell polymer particles were synthesized by free-radical dispersion copolymerization of 4-vinylpyridine (4VP) and various kinds of cross-linking reagents with methacryloyl-terminated polystyrene (PS) macromonomers in nonaqueous media such as 1,4-dioxane and cyclohexane. Well-defined particles were obtained by copolymerization of 4VP with ethylene glycol dimethacrylate (EGDM) in a dioxane medium. The particle diameters (D(n)=40-990 nm) decreased drastically both with increasing the feed concentration ratio of macromonomer to 4VP, [PS-M]/[4VP], and with increasing molecular weight of PS-M macromonomers. The particle size distribution (D(w)/D(n)) was in the range 1.02-1.10. PS-M macromonomers acted not only as comonomers but also as stabilizers. The particle diameters obtained in dioxane were smaller than those obtained in cyclohexane. Thus, we observed a tendency to smaller particle size as the media became more soluble for PS-M macromonomer.

Journal Article↗
PubMed1998

Aminoglycoside detection using a universal ELISA binding procedure onto polystyrene microtiter plates in comparison with HPLC analysis and microbiological agar-diffusion assay.

The use of enzyme-linked immunosorbent assay for the detection of aminoglycosides has been hindered due to low molecular weight compound adsorption to solid phases. Here, we describe an enzyme-linked immunosorbent assay based on the treatment of polystyrene microtiter plates with Alcian blue prepared in acetic acid prior to coating with the antibiotic. Whereas no detection of tobramycin was possible on commercially treated or untreated enzyme-linked immunosorbent assay plates, the Alcian blue treatment permitted detection of 0.025 and 0.05 microg ml(-1) of tobramycin respectively using 0.05 and 0.1% of Alcian blue with a coefficient of variation of 1.85 and 7.69%, respectively. Comparative studies of five tobramycin samples of unknown quantity using enzyme-linked immunosorbent assay and high-performance liquid chromatography gave equivalent results while those done via microbiological agar-diffusion assay were an overestimation of the actual quantity. The use of the Alcian blue pretreatment enzyme-linked immunosorbent assay procedure has permitted, in previous studies, the measure of antibodies against synthetic peptides and phospholipids. Subsequently, our demonstration of the sensitivity and reliability of this method in the quantification of tobramycin strongly suggests that the use of Alcian blue pretreatment in enzyme-linked immunosorbent assay can be applied universally to avert molecule immobilization problems on solid phases.

Agar↗
PubMed2000

Ultrasonic initiation of polystyrene latex synthesis

Polystyrene latex samples have been synthesised from an oil-in-water (o/w) emulsion of the monomer using ultrasonic irradiation as the initiation source. No added chemical initiators were used in any of the reactions. The free radicals formed from the cavitation process under the action of the ultrasound are sufficient to initiate the polymerisation. In the current study, the effects of varying the input intensity of the ultrasound were investigated. A marked increase in the monomer conversion rate as a function of time was seen as the power was increased. Despite this increase in conversion rate, the increasing intensity did not affect the resultant latex particle sizes. In all cases, the particle diameters at the conclusion of a polymerisation were seen to be in the range of 40 to 50 nm. The effects of changing the concentration of surfactant in the polymerisation medium and of changing the temperature were also probed. Increases in both were seen to lead to an increased rate of conversion at a fixed input intensity. Again, the particle diameters were invariant as a function of changing conditions. The small particle sizes and high conversion rates are thought to be due to a continuous nucleation process that is caused by the scavenging of free radicals throughout the polymerisation by freshly formed small oil droplets.

Journal Article↗
PubMed2002

Single-particle mass spectrometry of polystyrene microspheres and diamond nanocrystals.

High-resolution mass spectra of single submicrometer-sized particles are obtained using an electrospray ionization source in combination with an audio frequency quadrupole ion-trap mass spectrometer. Distinct from conventional methods, light scattering from a continuous Ar-ion laser is detected for particles ejected out of the ion trap. Typically, 10 particles are being trapped and interrogated in each measurement. With the audio frequency ion trap operated in a mass-selective instability mode, analysis of the particles reveals that they all differ in mass-to-charge ratio (m/z), and the individual peak in the observed mass spectrum is essentially derived from one single particle. A histogram of the spectra acquired in 10(2) repetitions of the experiment is equivalent to the single spectrum that would be observed when an ion ensemble of 10(3) particles is analyzed simultaneously using the single-particle mass spectrometer (SPMS). To calibrate such single-particle mass spectra, secular frequencies of the oscillatory motions of the individual particle within the trap are measured, and the trap parameter qz at the point of ejection is determined. A mass resolution exceeding 10(4) can readily be achieved in the absence of ion ensemble effect. We demonstrate in this work that the SPMS not only allows investigations of monodisperse polystyrene microspheres, but also is capable of detecting diamond nanoparticles with a nominal diameter of 100 nm, as well.

Diamond↗
PubMedDate not supplied

Polystyrene-supported triphenylarsine reagents and their use in Suzuki cross-coupling reactions.

Soluble and insoluble polystyrene-bound triphenylarsine reagents have been prepared from 4-styryldiphenylarsine. The utility of these reagents as ligands for palladium in Suzuki cross-coupling reactions is demonstrated. In these applications, the use of polymeric triphenylarsine simplifies the purification of the coupled product and allows for the ligand to be recycled. Furthermore, the soluble polymeric arsine reagent permits the palladium catalyst to be recovered and reused.

Journal Article↗
PubMed2007

Negative differential resistance and memory effect in diodes based on 1,4-dibenzyl C60 and zinc phthalocyanine doped polystyrene hybrid material.

Negative differential resistance (NDR) and memory effect were observed in diodes based on 1,4-dibenzyl C60 (DBC) and zinc phthalocyanine doped polystyrene hybrid material. Certain negative starting sweeping voltages led to a reproducible NDR, making the hybrid material a promising candidate in memory devices. It was found that the introduction of DBC enhanced the ON/OFF current ratio and significantly improved the memory stability. The ON/OFF current ratio was up to 2 orders of magnitude. The write-read-erase-reread cycles were more than 106, and the retention time reached 10,000 s without current degradation.

Journal Article↗
PubMed1998

Preparation and Photophysical Properties of Amide-Linked, Polypyridylruthenium-Derivatized Polystyrene.

The polymer poly(4{2-[N,N-bis(trimethylsilyl)amino]ethyl}styrene), prepared by anionic polymerization and of low polydispersity (M(w)/M(n) = 1.10-1.18), has been derivatized by amide linkage to [Ru(II)(bpy)(2)(4-(CO-)-4'-CH(3)-bpy)-](2+) (bpy is 2,2'-bipyridine; 4-(CO-)-4'-CH(3)-bpy is 4-carbonyl-4'-methyl-2,2'-bipyridine). Unreacted amine sites were converted into acetamides by treatment with acetic anhydride to give derivatized polymers of general formula [PS-CH(2)CH(2)NHCO(Ru(II)(n)()Me(m)())](PF(6))(2)(n)(), where m + n = 11, 18, or 25, PS represents the polystyrene backbone, and Ru(II) and Me represent the attached complex and acetamide, respectively. Spectral and electrochemical properties of the derivatized polymers are similar to those of the model [Ru(bpy)(2)(4-CONHCH(2)CH(2)C(6)H(5)-4'-CH(3)-bpy)](2+) (4-CONHCH(2)CH(2)C(6)H(5)-4'-CH(3)-bpy is 4'-methyl-2,2'-bipyridinyl-4-(2-phenylethylamide)), but emission quantum yields (phi(em)) and time-resolved emission decays are slightly dependent on the level of Ru(II) loading, with nonexponential, irradiation-dependent decays appearing at high loadings. The decays could be fitted satisfactorily to the first derivative of the Williams-Watts distribution function. These results are discussed with reference to possible structural and multichromophoric effects on excited-state decay.

Journal Article↗
PubMed2002

Synthesis of silver nanodisks using polystyrene mesospheres as templates.

We report the synthesis of Ag nanodisk using polystyrene mesospheres as templates. TEM measurements show that the average disk thickness is 9.0 +/- 1.0 nm and the diameter is 36 +/- 8 nm. The particles exhibit an intense electronic spectrum that differs markedly from that for spheres (purple vs yellow solutions). We present electromagnetic theory calculations which exhibit a qualitative match with the observed spectrum, enabling us to assign several of the plasmon resonance features.

Journal Article↗