Poly(N-isopropylacrylamide)-gated Fe3O4/SiO2 core shell nanoparticles with expanded mesoporous structures for the temperature triggered release of lysozyme.

Core-shell nanoparticles comprised of Fe3O4 cores and a mesoporous silica shell with an average expanded pore size of 6.07 nm and coated with a poly(N-isopropylacrylamide) (PNIPAM) layer (CS-MSNs-EP-PNIPAM) were prepared and characterized. The nanoparticles was loaded with (Ru(bipy)3(2+)) dye or an antibacterial enzyme, lysozyme, to obtain CS-MSNs-EP-PNIPAM-Ru(bipy)3(2+) and CS-MSNs-EP-PNIPAM-Lys, respectively. The lysozyme loading was determined to be 160 mg/g of nanoparticle. It was seen that Ru(bipy)3(2+) and lysozyme release was minimal at a room temperature of 25 °C while at physiological temperature (37 °C), abrupt release was observed. The applicability of the CS-MSNs-EP-PNIPAM-Lys was further tested with two Gram-positive bacteria samples, Bacillus cereus and Micrococcus luteus. At physiological temperature, the nanoparticles were shown to reduce bacterial growth, indicating a successful release of lysozyme from the nanoparticles. This nanoparticle system shows potential as a nanocarrier for the loading of similarly sized proteins or other species as a drug delivery platform.