Polystyrene particles adsorption

Figure 1. Adsorption isotherms of fully hydrolyzed PVA samples on 190nm polystyrene particles (o) Vinol 107 (A) Vinol 325 (D) Vinol 350 open points by adsorption method and shaded points by desorption method.

It is interesting to compare these results with the electrophoretic measurements made under identical electrolyte concentrations. Figure 8 shows that the variation of electrophoretic mobility with sodium chloride concentration is different for the bare and the PVA-covered particles. For the bare particles, the mobility remains constant up to a certain salt concentration, then increases to a maximum and decreases sharply, finally approaching zero. The maximum in electrophoretic mobility-electrolyte concentration curve with bare particles has been explained earlier (21) by postulating the adsorption of chloride ions on hydrophobic polystyrene particles. In contrast, for the PVA-covered particles, the mobility decreases with increasing electrolyte concentration until it approaches zero at high salt concentration. 

Valanne A, Suojanen J, Peltonen J, Soukka T, Hanninen P, Harma H (2009) Multiple sized europium(III) chelate-dyed polystyrene particles as donors in FRET - an application for sensitive protein quantification utilizing competitive adsorption. Analyst 134 980-986... 

St and divinylbenzene (DVB) were polymerized in a dispersion of acryl-amide-methacrylic acid-methylenebisacrylamide terpolymer particles (25). Fine polystyrene particles were formed in/on each seed terpolymer particle. The former was smaller by about one-twentieth than the latter. The distribution of polystyrene particles depended on the cross-link density. Different amounts of St and DVB were charged in the seeded polymerization, and the resulting composite particles were used for protein adsorption measurement to assess the hydrophobicity of the particle surface. The adsorbed amount was almost proportional to the amount of St and DVB charged. In contrast, cells were less stimulated by the 5% St-containing particle than by the 0% St-containing one, that is, the seed particle. This phenomenon is attributed to selective protein adsorption on the 5% St-containing particle (26). 

It is postulated that the main thermodynamic driving force for particle adsorption at the liquid-liquid interface is the osmotic repulsion between the colloidal particles and hydrophilic starch polymer molecules. This leads to an effective depletion flocculation of particles at the boundaries of the starch-rich regions. At the same time, the gelatin has a strong tendency to adsorb at the hydrophobic surface of the polystyrene particles, thereby conferring upon them some degree of thermodynamic... 

It can be seen from these data that the range of concentrations over which coagulation occurs is very narrow and that the c.c.c. is strongly dependent on the chain length of the hydrocarbon tail of the surfactant molecule. Studies of the electrophoretic mobility of the particles confirm that at the c.c.c the particle mobility becomes zero and studies of the adsorption suggest that up to this point the alkyl chains lie flat on the hydrocarbon-like surface of a polystyrene particle (36). 

Fournier C, Leonard M, Lecoqleonard I, Dellacherie E. Coating polystyrene particles by adsorption of hydrophobically-modified dextran. Langmuir 1995, 11, 2344—2347. 

Adsorption of block copolymers onto a surface is another pathway for surface functionalization. Block copolymers in solution of selective solvent afford the possibility to both self-assemble and adsorb onto a surface. The adsorption behavior is governed mostly by the interaction between the polymers and the solvent, but also by the size and the conformation of the polymer chains and by the interfacial contact energy of the polymer chains with the substrate [115-119], Indeed, in a selective solvent, one of the blocks is in a good solvent it swells and does not adsorb to the surface while the other block, which is in a poor solvent, will adsorb strongly to the surface to minimize its contact with the solvent. There have been a considerable number of studies dedicated to the adsorption of block copolymers to flat or curved surfaces, including adsorption of poly(/cr/-butylstyrcnc)-ft/od -sodium poly(styrenesulfonate) onto silica surfaces [120], polystyrene-Woc -poly(acrylic acid) onto weak polyelectrolyte multilayer surfaces [121], polyethylene-Wocfc-poly(ethylene oxide) on alkanethiol-patterned gold surfaces [122], or poly(ethylene oxide)-Woc -poly(lactide) onto colloidal polystyrene particles [123],... 

Much of the early studies of surfactant adsorption at the solid-solution interface were based on classical experimental techniques, such as solution depletion [1, 32], fluorescence spectroscopy [2], and measurements of the differential enthalpy of adsorption [2], Such methods have provided much of the basic initial understanding. However, they provide no direct structural information and are difficult to apply to mixtures [23, 34], However, when combined with other techniques, such as NMR and flow microcalorimetry, they provide some insight into the behaviour of mixtures. This was demonstrated by Thibaut et al. [33] on SDS/C10E5 mixtures adsorbed onto silica and by Colombie et al. [34] on the adsorption of SLS/Triton X-405 mixtures onto polystyrene particles. 

It is a matter of course that the different surfactant coverages are also reflected in the corresponding surface tensions y of the latexes (see Fig. 4b). An increase of the surface tension with increasing diameter is observed. The miniemulsions based on polystyrene particles exceeding 100 nm have a surface tension of close to the one of pure water (72 mN nr1)- This is due to the fact that the bare particle surface is so large that adsorption equilibrium ensures a very low surfactant solution concentration. Smaller particles with their higher sur-... 

The first reported work on the adsorption of ODNs onto charged colloids revealed marked affinity differences between sulfate- and amino-containing polystyrene latexes. In fact, low affinity has been observed for sulfated polystyrene particles, whereas high affinities are exhibited in the case of cationic (amine and amidine) polystyrene latexes (Fig. 2). 

In the case of sulfate charged latexes, the adsorption of ODN was reported to be independent of salinity. Such behavior was attributed to the hydrophobic interaction between the aromatic bases of ODN and the hydrophobic domains on the polystyrene particle surface [23]. 

Particle Concentration Fluorescence Immunoassay. The PCFIA is a solid-phase immunoassay in which proteins are attached to polystyrene particles by adsorption or covalent coupling for the solid phase and fluorescent-labeled reagents are utilized for product detection.22 The general principles of the assay are similar to those of the enzyme-linked immunosorbent assay (ELISA), which has been reviewed extensively elsewhere.23 PCFIAs are performed in specially designed 96-well format Fluoricon assay plates utilizing an automated Screen Machine (Idexx Corporation, Research Product Division, Portland, ME). 

The continuous decrease in A1203 incorporation in copper is also explained by a change in particle surface composition.43 Chloride present as an impurity forms CuCl, which adsorbs on the particles and thereby inhibits the adsorption of copper ions on the particles. This is an effect characteristic for a copper sulfate bath and was not found in nickel or cobalt baths. A different type of aging was reported for the codeposition of aggregated polystyrene particles with zinc.54,76 Polystyrene incorporation increased continuously in successive experiments, where the rotation speed of a cylinder electrode was randomly varied. Thixotropic viscous behavior of the aggregated suspension causes changes in aggregate size and suspension viscosity with rotation speed of the same time-scale as the experiments. 

For incorporation of polystyrene particles in copper55 56 and zinc54 75 76 a deviation from the Langmuir adsorption behavior at high particle bath concentration was observed (Fig. 7). The obtained particle composite content is higher than expected from the extrapolated curve at... 

Polystyrene latex particles, 0.2 p, in diameter, have recently been used as immunochemical markers for sceuining electron microscopyS. (SEM). But applications of such a reagent are limited because the lydrophobic surface of the polystyrene particles makes them stick nonspeciflcally to many surfaces and molecules. The same disadvantage applies to agglutination tests. Furthermore, reliance on weak adsorption forces to hold the antibodies on the particles is not always satisfactoryifi and chemical bonding of antibodies to polystyrene particles is virtually... 

Fig. 4.10. Sketch of adsorption of polydisperse particles at (a) low and (b) high salt concentrations. Dotted lines show the effective particle radius (or interaction distance), (c) Surface coverage of the polystyrene particles versus na ( a is a dimensionless screening parameter, where k is the inverse Debye length and a the particle diameter). The more polydisperse particles (41 versus 107nm) have a slightly increased coverage at high na. Solid curves are approximations derived from the effective hard sphere model (see [89] for further details)...

Fig. 4.16. Fabrication process for making Pt dots on ceria disks (1) adsorption of polystyrene particles on top of a Pt film on a ceria film, (2) melting of the colloids to hemispheres, (3) Ar+ etching through the Pt film and partially into the ceria film, (4) shrinking of the polystyrene hemispheres by a mild O2 plasma. The SEM image shows a 40-nm polystyrene hemisphere on top of a 160-irm Pt particle on a ceria film, (5) continued Ar+ etching into the ceria can be seen by the raised structure in the SEM image, and finally (6) removal of the PS by O2 plasma (from [91])...

The utilization of classical polystyrene particles or hydrophobic latexes for protein concentrations can induce undesirable phenomena such as protein denaturation and low concentration yields, on account of the high adsorption affinity between both species which may lead to a low desorbed amount. In addition, the use of such hydrophobic colloids in the polymerase chain reaction (PCR) of nucleic acid amplification step generally leads to total inhibition of the enzymatic reaction. The inhibition phenomena can be attributed to the denaturation of enzymes adsorbed in large numbers onto hydrophobic coUoids. The utilization of hydrophilic and highly hydrated latex particles (irrespective of temperature) is the key to solving this problem by suppressing the inhibition of enzyme activity. The purpose of this stage is then to focus on the potential apphcation of thermally responsive poly(NIPAM) particles for both protein and nucleic acid concentrations. 

Adsorption onto colloidal polystyrene results in very different behavior because of the hydrophobic nature of that surface. The addition of even a small amount of polystyrene particles to the polymer solution results in the complete disappearance of the excimer emission (Figure 6). In this case, the hydrophobic pyrene groups are strongly attracted to the polystyrene surface thus, the formation of excimers is precluded. A similar disappearance of the excimer was observed upon complexation with PMAA, a result indicating that the hydrophobic character of that polymer may hinder the formation of excimers by adsorbing the pyrene groups into a hydrophobic pocket. This observation is further supported by the fluorescence excitation spectra, presented in the next section. 

Excitation Spectra and Fluorescence Lifetimes. In this section, we further examine adsorption onto colloidal polystyrene by investigating the excitation spectrum of the adsorbed species. In Figure 7a, we show the excitation spectra of Py-PEG-Py(4250) before and after the addition of polystyrene particles. The spectrum undergoes a substantial red shift upon adsorption the main peak moves approximately 4 nm. A similar effect is found in the complexation with PMAA, as shown in Figure 3, where the monomer spectrum is again shifted to higher wavelengths. From these spectral shifts, we infer a spectral sensitivity to the environment. This sensitivity is illus-... 

Kondo, A., Murakami, F. and Higashitani, K. (1992) Circular dichroism studies on conformational changes in protein molecules upon adsorption on ultrafine polystyrene particles. Biotechnology and Bioengineering40, 889-894. 

Fabrication process for OSITs using colloidal lithography, (a) Adsorption of polystyrene particles on a glass substrate, (b) deposition of Al, AljOj, and Pt layers using the particles as evaporation masks, (c) removal of the particles using adhesive tape, and (d) dejxrsition of the organic semiconductor and Au layers. 

The effects of stabilizer molar mass have not often been studied. For use of PEOX to stabilize PMMA particles [21], a molar mass of 500 kg mol produced stable, monodisperse particles at lower concentration than 200 kg mol PEOX. For stabilization of polystyrene particles by HPC [29], it was the low viscosity (i.e. low molar mass) grade which gave the more stable dispersions. The predictions of Paine s grafting models were that the power law dependence of particle size on stabilizer molar mass would lie between the bounds -6 and (l-2d)/2, where b is the exponent relating the radius of gyration to molar mass. For PVP in methanol, h is 0.32 [43] and the predicted bounds are —0.32 to -H3.18. Figure 22.4, for PVP stabilization of PMMA particles in m anol [42], shows exponents of —0.25, —0.19 and —0.14 at 2, 4 and 6% PVP wdiich are closer to Paine s full adsorption model. 

J. Lee, P.A. Martic, and J.S. Tan. Protein adsorption on Pluronic copolymer-coated polystyrene particles. J. Colloid Interface ScL 131 252-266 (1989). 

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