DEXTRAN STABILIZED POLY(METHYL METHACRYLATE) LATEX-PARTICLES AND THEIR POTENTIAL APPLICATION FOR AFFINITY PURIFICATION OF LECTINS

Stable poly(methyl methacrylate) latex particles (220-360 nm in diamet er) using dextran as the protective colloid were prepared and characte rized in this study. Such an emulsion polymerization system follows Sm ith-Ewart Case III kinetics (i.e., the average number of free radicals per particle is greater than 0.5) due to the relatively large latex p article size. The carbohydrate content of these dextran modified emuls ion polymers shows a maximum around 5% dextran based on total monomer weight. The latex stability during polymerization is closely related t o the carbohydrate content of these latex particles, and it is control led by the ratio of the thickness of the dextran adsorption layer to t hat of the electric double layer of the latex particles. The critical flocculation concentration (CFC) of the latex products correlates well with the latex stability during polymerization. The greater the total scrap produced during polymerization (i.e., the stronger the bridging flocculation), the lower is the CFC of the latex products. The affini ty precipitation of concanavalin A (a model lectin used in this study) by the dextran modified PMMA latex particles is also illustrated in t his study. The specifically adsorbed concanavalin A increases with the carbohydrate content of the dextran modified latex particles.