Controlling morphology evolution of titanium oxide-gold nanourchin for photocatalytic degradation of dyes and photoinactivation of bacteria in the infected wound.

ABSTRACT

We report a one-pot, room-temperature, morphology-controlled synthesis of titanium oxide (TiOx)-gold nanocomposites (TiOx-Au NCs) using HAuCl4 and TiCl3 as precursors, and catechin as reducing agent. TiOx-Au NCs have a range of morphologies from star-like to urchin-like shape depending on the concentration of TiCl3 in the reaction mixture. The urchin-shaped TiOx-Au NCs exhibited excellent photocatalytic activity toward dye degradation due to strong light absorption, plasmon-induced excitation, high conductivity of the gold, and reduced hole-electron pair recombination. TiOx-Au NCs have the advantage of a wide range of light absorption and surface plasmon absorption-mediated excitation due to their abundant gold spikes, which enabled the degradation of dyes over 97% in 60 min, using a xenon lamp as a light source. In addition, TiOx-Au NCs are highly efficient for the photoinactivation of Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA), and Candida albicans through the photodynamic generation of reactive oxygen species (ROS) and damage to the bacterial membrane. The catechin derivatives on the NCs effectively promoted curing MRSA infected wounds in rats through inducing collagen synthesis, migration of keratinocytes, and neovascularization.