Development of new functionalized composite powders using plasma chemistry and its applications to drug engineering

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Plasma-induced low-density polyethylene (LDPE) radicals were studied in detail by electron spin resonance (ESR) by its comparison with ESR spectra of high-density polyethylene (HDPE). The observed ESR spectra of plasma-irradiated LDPE are largely different in pattern from those of HDPE.The systematic computer simulation disclosed that all these component radicals of LDPE were essentially identical to those of HDPE.One of the most special features unique to plasma-irradiated LDPE, however, is the fact that thermally stable dangling bond sites (DBS) is a major component radical instead of a mid-chain alkyl radical in HDPE.To gain a fundamental insight on elucidation of plasma-induced surface radicals of polycarbohydrates, the ESR study on plasma-irradiated dicarbohydrates, such as cellobiose and maltose, was performed on its comparison with those on amylose and cellulose. The simulated spectra disclosed that the observed spectra of cellobiose and maltose consisted of five and four kinds … More of spectral components, respectively. The special feature of the radical formation in dicarbohydrates is the fact that the formation of surface DBS is negligible.As the application in the development of new pharmaceutically useful materials using plasma-irradiated polymer, the new matrix-type drug delivery system (DDS) was prepared by the mechanochemical reaction of plasma-irradiated polymer in the presence of drug. The radical recombination reaction of plasma-irradiated PE by mechanochemical reaction was examined. It was shown that the radical recombination reaction of plasma-irradiated PE easily underwent by mechanochemical reaction and that the DBS disappeared faster than the mid-chain alkyl radical. Based on these experimental results, the drug release from the powdered sample prepared by mechanochemical reaction of plasma- irradiated PE in the presence of drug was examined. The drug was slowly released from the powdered sample. It is cleared that the matrix-type DDS can be prepared by the mechanochemical radical recombination reaction using plasma-irradiated PE.This method can be applicable to a wide variety of polymer and drug, and is useful for the development of the matrix-type DDS by the totally dry process. Less