Design of Porous Inorganic Nanoparticles Hybridized with Acetal-PEG-b-Polyamine Block Copolymers for High Performance Drug Carrier.

An advanced hybrid drug carrier has been developed using porous nanocrystals of a swellable clay mineral conjugated with a block copolymer containing poly (ethylene glycol) and polyamine segments. Synthetic hectorite (Laponite) or silica nanoparticles modified with α-acetal-poly (ethylene glycol)-block-poly[2- (N,N-dimethylamino) ethyl methacrylate] (acetal-PEG-b-PAMA) produced a homogeneous dispersion of an organic-inorganic hybrid in aqueous solution, which showed flocculation-resistive properties with an elevated ionic strength. The zeta-potential measurement revealed that nonionic PEG brush layers are formed on the surface of the clay nanocrystals since the negative charge of the clay surface was completely shielded by the nonionic PEG segment in the block copolymer. This charge neutralization explains the dispersion stability in solutions of high ionic strength. The average particle size of the PEG-modified hybrid was estimated to be 30-120 nm by dynamic light scattering. Pyrene, used as the model compound of a hydrophobic drug, was incorporated into the nanopores of the clay mineral without any remarkable expansion of the basal spacing. On the basis of these results, hybrids of porous inorganic nanoparticles coupled with acetal-PEG-b-PAMA are promising as new drug carrier systems. [ABSTRACT FROM AUTHOR]