Reusable Fe3O4 and WO3 immobilized onto montmorillonite as a photo-reactive antimicrobial agent

Abstract

Active near-infrared (NIR) tungsten oxide (WO₃) and iron oxide (Fe₃O₄) were immobilized in exfoliated montmorillonite (MMT) by the intercalation of 2-chloro-3′,4′-dihydroxyacetophenone and 1,3-propanesultone quaternized poly(dimethyl amino)ethyl methacrylate (C/S-PDMA) via ionic exchange reaction. UV-Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to confirm the construction of nanocomposites of an enlarged MMT layer with WO₃ and Fe₃O₄ by C/S-PDMA based on catechol chemistry. The metal oxides-immobilized MMT showed the colloidal stability and photothermal effect required for NIR mediated nanocomposites. The NIR mediated nanocomposites showed a high efficiency photothermal effect within 2 min towards both Gram positive (S. aureus) and Gram negative (E. coli) bacteria. Study of the recycled exfoliated MMT by the WO₃ and Fe₃O₄ complexed polymer study disclosed rapid and effective killing for both strains of bacteria within 4 min of NIR irradiation, in which almost 100% of both strains of bacteria were destroyed even after three cycles. This approach is promising for effective, rapid, and stable antibacterial photothermolysis agents.