Reversible Antimicrobial Photoswitching in Nanosilver

A reversible antimicrobial photoswitching of nanosilver using an optical wavelength-selective technique was reported. Finely dispersed nanosilver on semiconductor support (TiO₂) was synthesized rapidly through a one-step flame spray pyrolysis (FSP) of silver benzoate and titanium isopropoxide co-dissolved in acetonitrile/xylene. The results show that only a very minimal extent of nanosilver particle size increase takes place during the UV-A induced reduction due to its mild an dry condition. The nanometallic silver is found to be responsive to the visible light through its surface plasmon resonance, resulting in the excitation and reverse electron flow from the silver deposits to the conduction band (CB) of TiO₂. Switching-off of the sample by re-irradiating with UV-A for 40h results in fully reversible and indefinite cyclic characteristics of the Ag/TiO₂.