Layer-by-layer assembly of silver nanoparticles embedded polyelectrolyte multilayer on magnesium alloy with enhanced antibacterial property

Functionalization of magnesium alloy (Mg alloy) with multiple bioactivities is desired to obtain surfaces with improved biocompatibility and antibacterial property. In this article, an anticorrosive and antimicrobial coating was prepared on Mg alloy surface by layer-by-layer (LbL) assembly of polyelectrolytes. A polycationic copolymer (P(DOP-co-DMAEMA+)) bearing dopamine (DOP) and 2-(methacryloxy)ethyl trimethylammonium chloride (DMAEMA+) was synthesized and deposited on the surface of micro-arc oxidation (MAO) treated Mg alloy substrate as the first layer. The presence of DOP units ensure a strong anchoring on Mg alloy substrate, and the -N+(CH3)3 groups are sources of positive charge, providing electrostatic interaction with polyanion electrolyte. Negatively charged colloidal silver particles were prepared by using dextran sulfate (DS) as a stabilizer to precede chemical reduction by dextrose and served as a polyanion electrolyte. The functional polyelectrolyte multilayered films were obtained by alternating deposition P(DOP-co-DMAEMA+) and DS-stabilized silver colloid (DS-Ag) in a spin-assisted LbL assembly manner. The prepared nanosized silver colloids and functionalized Mg alloy were characterized by ultraviolet-visible (UV-vis) spectroscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Potentiodynamic polarization test confirmed that corrosion resistance of modified Mg alloy significantly increased and the fabricated polyelectrolyte multilayer films showed significant antibacterial activity.