Protein Degradation and RNA Efflux of Viruses Photocatalyzed by Graphene-Tungsten Oxide Composite Under Visible Light Irradiation

Graphene-tungsten oxide composite thin films with sheetlike surface morphology were fabricated and applied in photoinactivation of viruses under visible light irradiation. Using X-ray photoelectron spectroscopy, it was found that the chemically exfoliated graphene oxide sheets incorporated in the tungsten oxide film reduced through a visible light photocatalytic reduction. In addition, annealing the films at 450 degrees C in air resulted in formation of W-C and W-O-C bonds to obtain graphene-tungsten oxide composite films. The composite films fabricated by this method showed an excellent visible light photocatalytic performance in photoinactivation of bacteriophage MS2 viruses, as compared to tungsten oxide and as-prepared graphene-tungsten oxide films, which contained no W-C and W-O-C bonds. To study the inactivation mechanism of the viruses, breakage of protein capsid and then efflux of the viral RNA enveloped in the protein layer of the viruses were evaluated. The photocatalysis of the viruses on surface of the graphene-tungsten oxide composite film resulted in a nearly complete destruction of the viral protein and a sharp increase in the RNA efflux after 3 h light irradiation at room temperature. The composite film showed <10% reduction in the RNA efflux after 20 measurement cycles indicating stability in its photocatalytic performance up to 60 h irradiation.