Preparation and Characterization of Thermoresponsive Poly(N-isopropylacrylamide-co-acrylic acid)-Grafted Hollow Fe3O4/SiO2 Microspheres with Surface Holes for BSA Release

Thermoresponsive P(NIPAM-AA)/Fe3O4/SiO2microspheres with surface holes serving as carriers were prepared using p-Fe3O4/SiO2microspheres with a thermoresponsive copolymer. The p-Fe3O4/SiO2microspheres was obtained using a modified Pickering method and chemical etching. The surface pore size of p-Fe3O4/SiO2microspheres was in the range of 18.3 nm~37.2 nm and the cavity size was approximately 60 nm, which are suitable for loading and transporting biological macromolecules. P(NIPAM-AA) was synthesized inside and outside of the p-Fe3O4/SiO2microspheres via atom transfer radical polymerization of NIPAM, MBA and AA. The volume phase transition temperature (VPTT) of the specifically designed P(NIPAM-AA)/Fe3O4/SiO2microspheres was 42.5 °C. The saturation magnetization of P(NIPAM-AA)/Fe3O4/SiO2microspheres was 72.7 emu/g. The P(NIPAM-AA)/Fe3O4/SiO2microspheres were used as carriers to study the loading and release behavior of BSA. This microsphere system shows potential for the loading of proteins as a drug delivery platform.Keywords:P(NIPAM-AA);Fe3O4/SiO2hollow microspheres;holes;drug release