Preparation And Properties Of Functional Polymer Nanoparticles

The purpose of this work is to prepare nanoparticles with thermosensitive or bio-adhesive properties for drug delivery.Copolymers of poly(N-isopropylacrylamide) (PNIPAAm) and polyelectrolytes are expected to respond both to temperature and pH. When charged copolymers of PNIPAAm and polyelectrolytes interact with oppositely charged polymers, robust thermosensitive particles can be formed. After loading a certain drug by physical adsorption, the particles can exhibit a thermosensitive drug release property. Poly(allylamine)-g-PNIPAAm was synthesized by condensation between poly(allylamine) (PAH) and PNIPAAm-COOH. The copolymers exhibited the same lower critical solution temperature (LCST) regardless of their grafting ratios. A temperature cycle revealed completely reversible polymer aggregation and dissolution around the LCST. The LCST of the copolymers decreased linearly as a function of NaCl concentration. The particle size decreased along with the increase of pH. Robust PAH-g-PNIPAAm/PSS particles were prepared by physical crosslininking of the PAH-g-PNIPAAm nanoparticles by poly(styrene sulphonate) (PSS). A temperature cycle caused completely reversible particle deswelling and swelling. Different release performance of Rhodamine 6G at the swelling and deswelling states of the particles indicated the internal volume of the polymer network was temperature-tunable. The existence of amino and hydroxyl groups in the molecular chains of chitosan can give rise to hydrogen bonding with substances having hydroxyl groups, while the cationic nature of chitosan could provide electrostatic interaction with negatively charged surfaces. Therefore, chitosan is a promising candidate material for tooth adhesive drug delivery by the loading and release of toothpaste actives, so that the effect of the actives can be prolonged. Bio-adhesive chitosan nanoparticles were prepared via emulsification-crosslinking method. Cetylpyridine chloride and NaFwere loaded, showing sustained release properties. Both blank and active loadedchitosan nanoparticles had good adhesive properties on hydroxyapatite or glasssurface. Furthermore, blank and NaF loaded chitosan nanoparticles showed goodstability within the toothpaste matrix.