Bioreducible POSS-cored star-shaped polycation for efficient gene delivery.

The bioreducible star-shaped gene vector (POSS-(SS-PDMAEMA)8) with well-defined structure and relatively narrow molecular weight distribution was synthesized via atom transfer radical polymerization (ATRP) of (2-dimethylamino)ethyl methacrylate (DMAEMA) from a polyhedral oligomeric silsesquioxane (POSS) macroinitiator. POSS-(SS-PDMAEMA)8 was composed of a biocompatible POSS core and eight disulfide-linked PDMAEMA arms, wherein the PDMAEMA chain length could be adjusted by controlling polymerization time. POSS-(SS-PDMAEMA)8 can effectively bind pDNA into uniform nanocomplexes with appropriate particle size and zeta potential. The incorporation of disulfide bridges gave the POSS-(SS-PDMAEMA)8 material facile bioreducibility. In comparison with POSS-(PDMAEMA)8 without disulfide linkage, POSS-(SS-PDMAEMA)8 exhibited much lower cytotoxicity and substantially higher transfection efficiency. The present work would provide useful information for the design of new POSS-based drug/gene carriers.