RESUMEN
Titanium dioxide nanoparticles codoped with nitrogen and silver (Ag(2)O/TiON) were synthesized by the sol-gel process and found to be an effective visible light driven photocatalyst. The catalyst showed strong bactericidal activity against Escherichia coli (E. coli) under visible light irradiation (λ > 400 nm). In X-ray photoelectron spectroscopy and X-ray diffraction characterization of the samples, the as-added Ag species mainly exist as Ag(2)O. Spin trapping EPR study showed Ag addition greatly enhanced the production of hydroxyl radicals (â¢OH) under visible light irradiation. The results indicate that the Ag(2)O species trapped e(CB)(-) in the process of Ag(2)O/TiON photocatalytic reaction, thus inhibiting the recombination of e(CB)(-) and h(VB)(+) in agreement with the stronger photocatalytic bactericidal activity of Ag(2)O/TiON. The killing mechanism of Ag(2)O/TiON under visible light irradiation is shown to be related to oxidative damages in the forms of cell wall thinning and cell disconfiguration.
Asunto(s)
Antiinfecciosos/farmacología , Escherichia coli/efectos de los fármacos , Escherichia coli/efectos de la radiación , Luz , Nitrógeno/farmacología , Plata/farmacología , Titanio/farmacología , Catálisis/efectos de los fármacos , Catálisis/efectos de la radiación , Cristalografía por Rayos X , Desinfección , Espectroscopía de Resonancia por Spin del Electrón , Escherichia coli/ultraestructura , Radical Hidroxilo/química , Cinética , Pruebas de Sensibilidad Microbiana , Viabilidad Microbiana/efectos de los fármacos , Oxidación-Reducción/efectos de los fármacos , Oxidación-Reducción/efectos de la radiación , Óxidos/farmacología , Compuestos de Plata/farmacología , Espectrofotometría Ultravioleta , Detección de Spin , Factores de TiempoRESUMEN
Palladium-modified nitrogen-doped titanium dioxide (TiON/PdO) foams were synthesized by a sol-gel process on a polyurethane foam template. The TiON/PdO foam was tested for microbial killing using Escherichia coli cells as a target. Under visible-light illumination, the TiON/PdO foam displayed a strong antimicrobial effect on the bacteria cells in water. The antimicrobial effect was found to be dependent on the palladium content and the calcination temperature. In a flow-through dynamic photoreactor, the new photocatalyst efficiently inactivated E. coli within a short contact time (< 1 min), the shortest ever reported for photocatalytic killing of bacteria. The strong antimicrobial functions of the TiON/PdO foam were related to the charge trapping by PdO and to the high contact efficiency of the foam structure.