Silica coating of iron oxide magnetic nanoparticles by reverse microemulsion method and their functionalization with cationic polymer P(NIPAm-co-AMPTMA) for antibacterial vancomycin immobilization

Abstract

Iron oxide nanoparticles (IONPs) have previously been demonstrated as a platform for antibiotic drug carriers in biomedicine. In this work, a new approach has been envisioned to improve the colloidal stability of IONPs in aqueous media as well as drug-nanoparticle interactions through the surface modification with poly[N-isopropylacrylamide-co-(3-acrylamidopropyl) trimethylammonium chloride], P(NIPAm-co-AMPTMA) via a multi-step process. Briefly, surface modification of oleic acid coated nanoparticles (Fe3O4-OA), (prepared by co-precipitation), was carried out with tetraethylorthosilicate (TEOS) using an inverse microemulsion method and subsequently with reactive vinyl group (−CH = CH2) containing [3-(methacryloyloxy)propyl] trimethoxysilane (MPS) by a seed growth process. The MPS containing silica coated iron oxide particles (Fe3O4/SiO2), were used as seed for copolymerization of NIPAm and AMPTMA to obtain the thermally sensitive magnetic nanocomposites (MNCs), Fe3O4/SiO2/P(NIPAm-co-AMPTMA). Analysis of the prepared Fe3O4/SiO2/P(NIPAM-co-AMPTMA) nanocomposites showed well defined magnetic core and a modified silica shell with organic polymer. Changes in temperature resulted in alteration of the hydrodynamic diameter and zeta potential. To evaluate practical use of the MNCs, an antibacterial vancomycin was immobilized, and bacterial growth inhibition demonstrated the potential of these nanocomposites for application in biomedicine.