Green Synthesis and Surface Modification of Iron Oxide Nanoparticles with Enhanced Magnetization Using Natural Rubber Latex

Magnetic nanoparticles (MNPs) show great potential for many technological applications due to their superparamagnetic properties. Finding a green approach to producing biocompatible magnetic nanoparticles is of the utmost importance, especially for biomedical purposes. In the present study, the iron oxide nanoparticles were synthesized by a simple green coprecipitation method at a mild temperature, using natural rubber latex (NRL) extracted from Hevea brasiliensis as the capping agent. X-ray diffraction (XRD) patterns revealed a spinel structure of the magnetic nanoparticles (Fe3O4). Transmission electron microscopy (TEM) images showed that the core size of MNPs can be controlled by the NRL concentration. The zeta potential measurement of the NRL-coated and uncoated MNPs revealed higher colloidal stability for the NRL-coated MNPs. Fourier transform infrared spectroscopy (FTIR) suggested the presence of hydroxyl groups in the uncoated MNPs, probably due to residual water at the MNP surface. Absence of hydroxyl groups in the NRL-coated samples suggests that the binding of the MNPs to NRL molecules protects the magnetic cores from water, preventing hydration of the nanoparticle surface. Hall magnetometer measurements revealed that the iron oxide nanoparticles are superparamagnetic and that the NRL-coated magnetic nanoparticles have higher magnetization compared to the bare magnetic nanoparticles. Therefore, these results indicate that the NRL is an effective stabilizing agent to cover magnetic nanoparticles for biomedical applications.