Biodegradable polymeric nanoparticles as drug delivery systems have been investigated in this dissertation. The preparation and character of nanoparticles, the in vitro drug release, cytostatic activity and in vivo pharmacokinetics of drug-loaded nanoparticles were studied. The research was mainly concerned with the following aspects. 1. Doxorubicin-loaded chitosan nanoparticles(1) The chitosan nanoparticles were prepared by the ion cross-linked method. The optimum conditions for preparing smaller nanoparti...