pH-sensitive chitosan-based hydrogel nanoparticles through miniemulsion polymerization mediated by peroxide containing macromonomer

New type of hydrogel nanoparticles (HNp) based on chitosan are synthesized by the free radical graft-copolymerization reaction of peroxide containing chitosan derivative and 1-vinyl-2-pyrrolidone (VP) in the inverse miniemulsion droplets. Free radicals are formed upon thermal decomposition of the peroxide groups that are attached to the chitosan chain. After introduction of the cross-linker N,N-methylenebisacrylamide, more densely cross-linked HNp with a lower pH-dependant swelling rate are produced. The release behavior is investigated by fluorescence measurements using HNp loaded with either anionic sulforhodamine 101 or cationic rhodamine 123 fluorescent dye. The obtained results revealed that the crucial points in the release kinetic are the nature of used "payload" molecules and their interaction with the hydrogel matrix. Synthesized HNp are of potential interest for diverse biomedical applications including controlled drug release and diagnostic.