Facile functionalization and phase reduction route of magnetic iron oxide nanoparticles for conjugation of matrix metalloproteinase

A protocol for the simultaneous functionalization and phase reduction route of iron oxide magnetic nanoparticles (MNPs) and its further bioconjugation is presented. It was found that surface functionalization of maghemite (γ-Fe₂O₃) nanoparticles with mercaptopropyltrimethoxysilane (MPTMS) under anoxic environment at above 80 °C promotes in situ conversion to magnetite (Fe₃O₄). Full conversion to Fe₃O₄, as probed by Mössbauer spectroscopy, with accompanied increase in the composite saturation magnetization, was achieved at 120 °C. By controlling the MPTMS concentration, the resultant silane-MNPs morphology can be tuned from having homogeneous thin layer (2-weighted MRI contrast can be achieved simultaneously. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.