[Fundamentals of plasma chemistry and its application to drug engineering]

In this review, our novel research works in both low temperature plasma chemistry and solid state plasma chemistry were described. As for low temperature plasma, the ESR study on plasma-induced radicals of several selected conventional polymers was shown including the detailed analyses of the radical structure and the mechanism by which the radicals were formed on typical degradable methacrylic polymers and cross-linkable polystyrene. One of the pharmaceutical applications of the plasma processing for drug delivery system (DDS) was also described, which includes the preparations of double-compressed tablet consisting of drugs as a core material and various types of polymers as a wall material followed by plasma-irradiation on such a tablet. As for solid state plasma, the detailed reaction mechanism of solid state mechanochemical polymerization was shown including the solid state single electron transfer and the special feature of the resulting polymers. The structural criteria for polymerizable monomer derived from the quantum chemical considerations were also established. Based on the above findings, we synthesized various polymeric prodrugs by mechanochemical polymerization and studied the nature of hydrolyses (drug release).