Fabrication of magnetite-hydrogel nanocomposites with clustered magnetite cores and poly(N-isopropylacrylamide-co-acrylic acid) shells for drug delivery application.

Magnetite-hydrogel nanocomposites were fabricated through the combination of sol-gel process and radical polymerization. The incorporation of magnetite clusters into silica matrix was facilely conducted by the sol-gel reaction of APTMS-complexed CMNPs (citrate-stabilized magnetites) and tetraethoxysilane (TEOS) in ethanol solution. The core-shell magnetic nanoparticles were further encapsulated with poly(N-isopropylacrylamide-co-acrylic acid) hydrogeals via a free radical polymerization. The magnetic nanoparticles exhibited superparamagnetic characteristics with negligible remanence and coercivity. Hydrogel-encapsulated magnetic nanoparticles showed systematic changes of particle size corresponding to the alteration of pH and temperature. The resulting nanocomposites can be a smart drug delivery agent with magnetic and stimuli (pH, temperature)-sensitive properties.