Magnetic Responsive Hydrogel Material Delivery System II

摘要

We have developed a novel route for the synthesis of the thermoresponsive core-shell nanoparticles that consist of the magnetite core and the poly(N-isoproplyacrylamide) (poly(NIPAAm)) shell in aqueous medium. Magnetic nanoparticles (MNPs) were coated with first oleic acid (OA) and then vinyl carboxylic acid-beta-cyclodextrin (MAH-beta-CD). The OA-MNPs and the MAH- beta-CD-MNPs showed mono-dispersion in a n-hexane and aqueous medium, respectively. NIPAAms were successfully polymerized from the vinyl double bonds of the MAH-beta-CD MNPs and cross-linked with N, N-methylenebisacrylamide (MBA) to make the stable thermo-responsive core-shell morphology with the MNP core and the poly(NIPAAm) shell (poly(NIPAAm)-MNP). The aqueous solutions dispersed with poly (NIPAAm)-MNPs showed magnetic heating due to a super paramagnetic property, and the poly (NIPAAm) shell shrank above its LCST temperature. Apart from aqueous dispersed solution PNIPAAm magnetite composite film can also be prepared via photopolymerization using APS as a photo initiator. The film synthesized is cross linked with MBA and thus insoluble in water. When AC magnetic field is applied on such a PNIPAAm nanocomposite film, MNPS oscillate and produce heat and as a result PNIPAAm shrinkage can be observed. The combination of these properties are potentially important in target delivery of therapeutic agent in vivo, hyperthermic treatment of tumors, magnetic resonance imaging (MRI) as contrasting agents, tissue repair, immunoassay, cell separation, biomagnetic separation of biomolecules, etc.