Fluorescent latex particles

Acrolein-containing latex particles were used for immobilization of proteins. The latex particles were prepared by emulsifier-free polymerization of acrolein and styrene (Table I). Fluorescent latex particles were prepared by mixing fluorescent dyes such as Hostalux KCB (Hoechst) or coumarin-6 into styrene before the emulsion polymerization (Table I). To increase the immunological sensitivity of the protein-conjugated latex particles, a hexyl group was introduced between the latex particle and the protein (Protein-spacer-latex). Proteins such as human serum albumin (HSA), anti-human serum albumin (anti-HSA-IgG), and a fragmented antibody (anti-HSA-... 

Functional group labeling and detection with fluorescent latex particles Fluorescent dye loaded micro- and nanoparticles. Diagnostic assay use (particularly in immunochromatography tests) and flow cytometry. 33... 

Pappo, J., and Ermak, T. H., 1989, Uptake and translocation of fluorescent latex particles by rabbit Peyer s patch follicle epithelium A quantitative model for M cell uptake, Clin. Exp. Immunol. 76 144-148. 

Protein adsorption has been studied with a variety of techniques such as ellipsome-try [107,108], ESCA [109], surface forces measurements [102], total internal reflection fluorescence (TIRE) [103,110], electron microscopy [111], and electrokinetic measurement of latex particles [112,113] and capillaries [114], The TIRE technique has recently been adapted to observe surface diffusion [106] and orientation [IIS] in adsorbed layers. These experiments point toward the significant influence of the protein-surface interaction on the adsorption characteristics [105,108,110]. A very important interaction is due to the hydrophobic interaction between parts of the protein and polymeric surfaces [18], although often electrostatic interactions are also influential [ 116]. Protein desorption can be affected by altering the pH [117] or by the introduction of a complexing agent [118]. 

The original polymeric latex particles still are widely used for separation and detection. Polymers provide a matrix that can be swollen for embedding other molecules in their core, such as organic dyes or fluorescent molecules. Even nanoparticle quantum dots can be incorporated into larger latex particles to form highly fluorescent composite microparticles. 

Fig. 1. Fluorescence histogram profiles of singlet and doublet 0.92-pm latex particles (A), S. aureus Bioparticles (B), and Zymosan Bioparticles (C).

Fig. 3. Effects of photodetector settings on fluorescence histogram profiles of granulocytes exposed to opsonized 0.92- j,m latex particles. Photodetector settings that are too low (A) or too high (B) are compared with correctly adjusted photodetection (C).

The latexes were ion-exchanged with Dowex 50W(H+) resin and the Dowex 50W(H+)-Dowex 1 (0H ) mixed resin in combination with the Dowex 50W(Na" ")-Dowex 1 (0H ) resin, and the ion-exchanged samples were titrated conductometrically. The samples treated were the latex, the aqueous serum, the latex particles separated from the serum, and the latex particles swollen or dissolved in 80 20 dioxane-water mixture. The total oxygen content was determined by neutron activation and the total sulfur content by X-ray fluorescence. Material balances of acrylic or methacrylic acid found in the serum, on the particle surface, and inside the particle agreed with the amount added to within 5-10%. 

The introduction of a fluorescence dye into the latex particles enabled us to confirm that the association took place specifically between different kinds of latex particles. 

Kato, N., and Caruso, F. (2005). Homogeneous, competitive fluorescence quenching immunoassay based on gold nanoparticle/polyelectrolyte coated latex particles. J. Phys. Chem. B 109 19604-19612. 

While no real labels meet all of these needs, the properties of some of the more recently introduced labelling systems are approaching the ideal. Radioisotopes, once the only type of label used for immunoassays, have clearly been overwhelmed by current applications of fluorescent labeling methods, enzyme labels, and even coenzyme and prosthetic group labels. A variety of alternative labels has also been investigated, including red blood cells, latex particles, viruses, metals, and free radicals. Table 6.1 shows a representative listing of labels used in modem immunoassays.1... 

There continues to be extensive interest in latexes and micellar systems. The structure of acrylic latex particles has been investigated by non-radiative energy transfer by labelling the co-monomers with fluorescent acceptor-donor systems. Phase separations could also be measured in this way. Excimer fluorescence has been used to measure the critical micelle temperature in diblock copolymers of polystyrene with ethylene-propylene and the results agree well with dynamic light scattering measurements. Fluorescence anisotropy has been used to measure adsorption isotherms of labelled polymers to silica as well as segmental relaxation processes in solutions of acrylic polymers. In the latter case unusual interactions were indicated between the polymers and chlorinated hydrocarbon solvents. Fluorescence analysis of hydrophobically modifled cellulose have shown the operation of slow dynamic processes while fluorescence... 

Hydrophobic fluorescent probes have been bound onto copolymers of 2-dialkylaminoethyl methacrylate-N-vinyl-2-pyrrolidone and compared with effects of dye binding l and in an amphiphilic copolymer of jl-styrenesulphonate with butyl methacrylate containing vinyl carbazole as a fluorescent probe only monomer fluorescence was observed especially in water where the polymer formed latex particles . two molecular populations have been observed for an oxadiazole dye in poly(l-trimethylsilyl-l-propyne)353 while a... 

Fluorescent microspheres Yellow-green Huoresbrite polystyrene latex particles (1 J,m) (Polyscience, Inc., Warrington, PA) 1% solids in 5% heat-inactivated FCS and incubated at 37°C for 30 min immediately prior to use. Incubation with FCS allows optimal opsonization. 

FIGURE 44.15 Fluorescence images of 4.7 pm latex particles inside the 75 pm I.D. capillary without (a) and with (b) activated transducer. (Reproduced from Wiklund M., et al., Ultrasonics, 41, 329, 2003. With permission.)... 

Another strategy consists in the use of QDs coated with a cysteine acrylamide, a polymerizable stabilizer [304]. Successful incorporation of hydrophilic cysteine-acrylamide-stabilized QDs into 80-200 nm fluorescent latexes was achieved via emulsion polymerization, as reported by Sherman et al. [308], using two different procedures. In the first, a two-step shot growth surfactant-free emulsion polymerization of styrene and NaSS was performed in the presence of a solution of hydrophilic cysteine-acrylamide-stabilized CdS or CdSe/CdS QDs. In the second approach, CdSe/CdS QDs were first electrostatically modified by vinylbenzyl(trimethyl)-ammonium chloride and subsequently copolymerized with styrene in the presence of SDS. A third approach was also described in this paper coating of cationic PS particles with anionic poly(cysteine acrylamide)-coated QDs through electrostatic-driven interactions. 

Bradley M, Ashokkumar M, Grieser F (2003) Sonochemical production of fluorescent and phosphorescent latex particles. J Am Chem Soc 125 525-529... 

Cross-coupling reactions were carried out in direct aqueous miniemulsions with 1,2,4-tribromobenzene as crosslinker, and Pd as catalyst [147], in order to obtain aqueous latexes of crosslinked poly(p-phenylene ethynylene) with good optoelectronic properties. The Glaser couphng reaction was also used to synthesize fluorescent conjugated particles of poly(arylene diethynylenes) in direct miniemulsions [148]. For this, 4,4 -dinonyl-2,2 -bipyridine was found to be a suitable ligand for solubilizing the copper (I) chloride catalyst in the toluene droplets. In this case, a solution of the monomers in toluene was first mixed with the solution of the catalyst, and the resultant mixture then miniemulsified in an aqueous solution of cationic surfactant. 

The other interesting method utilises fluorescence measurements. This approach has been mainly applied to latex film formation by Winnik and Wang [90]. In this technique, latex is prepared in two different batches. In one batch, the chains contain a donor group, while in the other, an acceptor group is attached. The interdiffusion of polymer chains between neighbouring latex particles is then studied by direct non-radiative energy transfer measurements. 

Polymer latex particles are usually benign in the body and may be functionalised to improve biocompatibility. There are many potential biomedical applications of latexes. Emulsions have potential relevance in the area of controlled-release drug-delivery (246, 253, 259). Because emulsion polymers have substantial interfacial areas, they are potentially useful as supports for use in relatively low-temperature biocatalysis applications (171, 308). Fluorescent-dyed latex particles (218) are... 

The technique of pyrene fluorescence intensity measurements was proposed to study the particle nucleation mechanisms involved in the 0/W microemulsion polymerization (31). The experimental data showed that microemulsion droplets are the major particle nucleation loci for the polymerization system with the more hydrophobic ST as the monomer. This is followed by the flocculation of latex particles with the remaining droplets. In contrast, the polymer reactions taking place initially in the continuous aqueous phase (homogeneous nucleation) plays an important role in the MMA microemulsion polymerization. 

In OM, the spatial resolution both lateral (parallel to the focal plane) and axial (perpendicular to the focal plane) is always a critical issue. As to the lateral resolution, laser scanning confocal fluorescence microscopy (LSCFM) has a high resolution of 0.42A/NA, where NA is the numerical aperture hence, the use of a large NA objective with blue laser hght allows one to achieve a high resolution of less than 200 nm [3]. Polymer films containing coumarine-labeled latex particles with diameters of 500,220, or 100 nm were examined to estimate the resolution of LSCFM [4]. The measurement of a single latex particle proved that the accuracy of the setup was in the order of 200 nm laterally and 400 nm axially. 

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