Magnetically-Triggered Release of Entrapped Bioactive Proteins from Thermally Responsive Polymer-Coated Iron Oxide Nanoparticles for Stem Cell Proliferation

Nanoparticles could conceal bioactive proteins during therapeutic delivery, avoiding side effects. Superparamagnetic iron oxide nanoparticles (SPIONs) coated with a temperature-sensitive polymer were tested for protein release. We show that coated SPIONs can entrap test proteins and release them in a temperature-controlled manner in a biological system. Magnetically heating SPIONs triggered protein release at bulk solution temperatures below polymer transition. The entrapped growth factor Wnt3a was inactive until magnetically-triggered release, upon which it could increase mesenchymal stem cell proliferation. Once chemically adjusting polymer transition above body temperature this system could be used for targeted cell stimulation in model animals and humans.