Preparation of PMMA/acid-modified chitosan core-shell nanoparticles and their potential as gene carriers

The core-shell nanoparticles consisting of poly(methyl methacrylate) (PMMA) cores surrounded by various acid-modified chitosan shells were synthesized using a surfactant-free emulsion copolymerization, induced by a tert-butylhydroperoxide (TBHP) solution. Methyl methacrylate (MMA) was grafted onto four acid-modified chitosans (hydrochloric, lactic, aspartic, and glutamic acids) with MMA conversions up to 64%. The prepared nanoparticles had diameter ranging from 100 to 300 nm characterized by atomic force microscopy and displayed highly positive surface charges up to +77 mV. Transmission electron microscopic images clearly revealed well-defined core-shell morphology of the nanoparticles where PMMA cores were coated with acid-modified chitosan shells. The effect of acid-modified chitosans on particle size, intensity of surface charge, morphology, and thermal stability were determined systematically. The plasmid DNA/nanoparticles complexes were investigated with ζ-potential measurement. The results suggested that these nanoparticles can effectively complex with plasmid DNAs via electrostatic interaction and could be used as gene carriers.