Facile technique for preparing organic–inorganic composite particles: Monodisperse poly(lactide-co-glycolide) (PLGA) particles having silica nanoparticles on the surface

This paper presents a facile technique for preparing organic–inorganic composite particles. The technique involves coating 50-nm silica nanospheres as model composites on the surface of monodisperse PLGA particles. Monodisperse poly(lactide-co-glycolide) (PLGA) particles (size: 2.0 μm) with molecular weights (Mw) of 5000, 10,000, 15,000, and 20,000 are first prepared using a Shirasu porous glass (SPG) membrane emulsification technique and a solvent evaporation method. Monodisperse PLGA particles (sizes: 0.70, 1.00, 2.00, and 3.00 μm, Mw: 20,000) are also prepared by varying the pore size of the SPG membrane used. The surfaces of the prepared PLGA particles are modified by the adsorption of a polyelectrolyte having counter-ions, which results in the formation of positively charged PLGA particles from the original anionic particles. Silica nanospheres (size: 50 nm) are coated on the surface of the modified PLGA particles via electrostatic interaction in order to prepare the organic–inorganic composite particles. Compared with simple PLGA particles, the prepared composite particles have a unique functionality for biological applications.