谷口 竜王

© 2016 Elsevier B.V. Luminescent particles have been attracting significant attention because they can be used in biochemical applications, such as detecting and imaging biomolecules. In this study, luminescent polystyrene latex particles were prepared through miniemulsion polymerization of styrene with dissolved europium complexes in the presence of bovine serum albumin (BSA) and poly(ethylene glycol) monomethoxy methacrylate as surfactants. The solubility of the europium complex in styrene has a strong effect on the yield of the particle. Europium tris(2-thenoyl trifluoroacetonate) di(tri-n-octyl phosphine oxide), which has a high solubility in styrene, was sufficiently incorporated into the polystyrene particles compared to europium tris(2-thenoyl trifluoroacetonate), which has a low solubility in styrene. The luminescence property of the europium complex could remain intact even after its incorporation through the miniemulsion polymerization. In the aqueous dispersion, the resulting particles could emit strong luminescence, which is a characteristic of the europium complex. The antibody fragments were covalently attached to BSA-covered particles after a reaction with a bifunctional linker, N-(6-maleimidocaproyloxy)succinimide. The time-resolved fluoroimmunoassay technique showed that 3.3 pg/mL of human α-fetoproteins (AFP) can be detected by using the resulting luminescent particles. An immunochromatographic assay using the resulting particles was also performed as a convenient method to qualitatively detect biomolecules. The detection limit of AFP measured by the immunochromatographic assay was determined to be 2000 pg/mL. These results revealed that the luminescent particles obtained in this study can be utilized for the highly sensitive detection of biomolecules and in vitro biochemical diagnosis.

© 2015 Elsevier B.V. Polystyrene latex particles with controlled size were prepared by polymerization of oil-in-water (O/W) emulsion styrene droplets obtained through the phase inversion temperature (PIT) emulsification using amphiphilic comb-like block polymers, polystyrene-b-poly[oligo(ethylene glycol) methyl ether methacrylate] (PStn-b-POEGMAm-Cl). PStn-b-POEGMAm-Cl block polymers were synthesized by sequential atom transfer radical polymerization (ATRP) of St and OEGMA. The interfacial properties of PStn-b-POEGMAm-Cl in aqueous media were investigated by means of surface tension measurement, fluorescence probe technique, and transmittance measurement. The length of hydrophobic PSt block chain was found to affect the critical micelle concentration, the micelle aggregation number, and the cloud point. O/W emulsions were obtained through the PIT process using PStn-b-POEGMAm-Cl as a surfactant by lowering the temperature of emulsions below the PIT in an ice bath. PSt particles with precisely controlled size in a range between 30 and 120nm were successfully prepared by a free radical polymerization of St droplets initiated by the water- or oil-soluble initiators. FE-SEM observation revealed that the morphology of polystyrene particles was found to depend on the relative PSt chain length of PStn-b-POEGMAm-Cl.

© 2014 Elsevier Ltd. All rights reserved. We prepared the novel fluorescent polymer latex particles which can change their fluorescence intensity in response to the increasing NaCl concentration in water. Core polymer latex particles were synthesized by emulsifier-free emulsion polymerization of styrene and 2-(2-chloroisobutyroyloxy)ethyl methacrylate. Hydrophilic polymer chains containing epoxy groups were grafted from the core particles by surface-initiated atom transfer radical copolymerization of methoxy polyethyleneglycol methacrylate (MEO x MA, x = 4 or 9) and glycidyl methacrylate in aqueous media. After azidation of epoxy groups in graft chains, a water-soluble fluorescent dansyl derivative was successfully coupled with the graft chains by copper-catalyzed azide-alkyne cycloaddition in aqueous media. The wavelength of maximum fluorescence intensity of polymer particles carrying graft chains with longer PEG side chains (x = 9) was slightly blue-shifted (7 nm) and the fluorescence intensity increased (1.35 times) with an increase in NaCl concentration as opposed to polymer particles with shorter PEG chains (x = 4).

A novel technique of particle monolayer fabrication based on hydrophobic interactions in aqueous systems is described in this paper. When alkylated glass plates modified with various silane coupling agents were immersed in aqueous dispersions of submicron-sized polystyrene particles of cationic or anionic surface charges, cationic particle monolayers containing active ester groups were effectively formed at the plate surfaces, whereas no anionic particles were self-organized on the plate surfaces. The coverage of the plates with cationic particles and the morphology of the monolayers varied with the hydrophobicities of the particles and plates as well as with the ionic strength of the medium and temperature. For less hydrophobic methylated glass surfaces modified with methyltriethoxysilane, cationic particles were self-organized at relatively regular intervals, whereas they were self-organized in the form of aggregates for the more hydrophobic octadecylated glass plates treated with n-octadecyltriethoxysilane. Closely packed monolayers were fabricated by adjusting ionic strength and temperature. Fluorescence labelling of cationic particle monolayers was successfully accomplished by the reaction of remaining active ester groups on the monolayers with a fluorescence probe containing amino groups. Cationic particle monolayers were physically stabilized by heating above the glass transition temperature (T-g) of the particles.

Submicron-sized cationic polystyrene shell particles with active ester groups were effectively self-assembled on hydrophobic surfaces of cross-linked polystyrene (PST) particles, uncharged core particles with ca. 8.5-mum diameter in aqueous systems. The hydrophobic interactions between the shell particles and core particles play a key role in heterocoagulation. The resulting heterocoagulates were highly physically stable in water, and the morphology was controlled by several factors including the solid content of latex, self-assembling time, and electrolyte concentration. Composite polymer particles with a core-shell structure were successfully obtained from the heterocoagulates by heat treatment for 3 h at a temperature above the glass transition temperature (T-g) of the cationic polymer shell particles.

The adsorption of anti-a-feto protein (anti-AFP) onto polystyrene-core-poly(N-isopropylacrylamide)-shell particles was investigated as a function of temperature, pH, and salinity. The influence of various physicochemical parameters onto the colloidal and surface properties of such stimuli-responsive particles was first studied. Then, the adsorption of anti-AFP antibody was investigated in order to point out the driving forces involved in the adsorption process. The effects of salinity, pH, and temperature demonstrated that adsorption was mainly governed by electrostatic interactions. In addition, the adsorption isotherms were analyzed on the basis of a Langmuir model leading to the determination of affinity constants. Finally, based on this adsorption study, various covalent coupling methodologies of the antibody were compared by using two different copolymers as a reactive spacer arm. The amount of chemically grafted antibody was obtained after performing the desorption step (by lowering the temperature, changing the pH, or raising ionic strength). The grafted quantity of antibody was found to be related to the adsorbed amount as a function of pH and ionic strength. (C) 2002 Elsevier Science B.V. All rights reserved.

The adsorption of anti-a-feto protein (anti-AFP) onto polystyrene-core-poly(N-isopropylacrylamide)-shell particles was investigated as a function of temperature, pH, and salinity. The influence of various physicochemical parameters onto the colloidal and surface properties of such stimuli-responsive particles was first studied. Then, the adsorption of anti-AFP antibody was investigated in order to point out the driving forces involved in the adsorption process. The effects of salinity, pH, and temperature demonstrated that adsorption was mainly governed by electrostatic interactions. In addition, the adsorption isotherms were analyzed on the basis of a Langmuir model leading to the determination of affinity constants. Finally, based on this adsorption study, various covalent coupling methodologies of the antibody were compared by using two different copolymers as a reactive spacer arm. The amount of chemically grafted antibody was obtained after performing the desorption step (by lowering the temperature, changing the pH, or raising ionic strength). The grafted quantity of antibody was found to be related to the adsorbed amount as a function of pH and ionic strength. (C) 2002 Elsevier Science B.V. All rights reserved.