Immobilization of protein on Fe3O4 nanoparticles for magnetic hyperthermia application.

We report a facile approach for the preparation of protein conjugated glutaric acid functionalized Fe3O4 magnetic nanoparticles (Pro-Glu-MNPs), having improved colloidal stability and heating efficacy. The Pro-Glu-MNPs were prepared by covalent conjugation of BSA protein onto the surface of glutaric acid functionalized Fe3O4 magnetic nanoparticles (Glu-MNPs) obtained through thermal decomposition. XRD and TEM analyses confirmed the formation of crystalline Fe3O4 nanoparticles of average size ~5 nm, whereas the conjugation of BSA protein to them was evident from XPS, FTIR, TGA, DLS and zeta-potential measurements. These Pro-Glu-MNPs showed good colloidal stability in different media (water, phosphate buffer saline, cell culture medium) and exhibited room temperature superparamagnetism with good magnetic field responsivity towards the external magnet. The induction heating studies revealed that the heating efficacy of these Pro-Glu-MNPs was strongly reliant on the particle concentration and their stabilizing media. In addition, they showed enhanced heating efficacy over Glu-MNPs as surface passivation by protein offers colloidal stability to them as well as prevents their aggregation under AC magnetic field. Further, Pro-Glu-MNPs are biocompatible towards normal cells and showed substantial cellular internalization in cancerous cells, suggesting their potential application in hyperthermia therapy.