Pure and Applied Chemistry

Abstract: Plasma-induced surface radicals formed on a variety of organic polymers have been studied by electron spin resonance (ESR), making it possible to provide a sound basis for future experimental design of polymer surface processing (i.e., plasma treatment). On the basis of the findings from such studies on the nature of radical formation and radical reactivity, several novel bioapplications in the field of biomedical and drug engineering have been developed. Applications derived from the nature of plasma-induced surface radical formation include the preparation of a reservoir-type drug delivery system (DDS) of sustained and delayed release, and a floating drug delivery system (FDDS) possessing gastric retention capabilities, the combined findings leading to preparation of a novel “patient-tailored DDS” administered under consideration of the fact that the environment (pH and transit time, etc.) in the gastrointestinal (GI) tract varies with each patient. Applications derived from the reactivity of plasma-induced surface radicals include the preparation of composite powders applicable to a matrix-type DDS by making a mechanical application to the surface radical-containing polymer powders with drug powders, plasma-assisted immobilization of oligo-nucleotides (DNA) onto polymer surfaces applicable to constructing a DNA diagnosis system, and basic study of plasma-assisted preparation of a novel functionalized chemo-embolic agent of non-crosslinked hydrogel, vinyl alcohol-sodium acrylate copolymer (PVA‑PAANa).