Page - (000361) - in Biomedical Chemistry: Current Trends and Developments

2002). Chuan have developed a novel nanosystem consisting of a self- assembling poly(ethyleneglycol)-disulfide-paclitaxel (PEG-SS-PTX/PTX) delivery vector containing free paclitaxel (PTX) and conjugated PTX in the same nanoparticulate system with a redox-triggered drug-release mechanism (Fig. 3.5.5). The principle is based on the instability of disulfide bonds in a reductive environment. The authors were able to improve the drug loading method, obtain programmed drug release, reduce the drug toxicity, and enhance the antitumor efficacy (Chuan, 2014). Figure 3.5.5: Schematic representation of the self-assembly, accumulation at the tumor site, uptake by tumor cells, and triggered intracellular drug release of redox-responsive PEG-SS- PTX/PTX nanoparticles. The programmed drug release undergoes two phases: release of loaded PTX and conjugated PTX. Abbreviations: PTX, paclitaxel, GSH, glutathione, EPR, enhanced permeability and retention effect. Reprinted with permission from (Chuan, 2014). Variations in the composition and expression of local enzymes are other