Graphene oxide/polyvinylpyrrolidone composite coating on 316L SS with superior antibacterial and anti-biofouling properties

Abstract

Here, we report the fabrication of a graphene oxide (GO)/polyvinylpyrrolidone (PVP) (GP) composite coating on 316L stainless steel (SS) with superior antibacterial and anti-biofouling performance using electrophoretic deposition (EPD). At an optimal EPD condition (10 V, 60 s), PVP and GO concentrations of 0.03 and 0.1 wt%, respectively, a uniform crack free coating with superior antibacterial and anti-biofouling properties is obtained. The morphology and composition of the composite coating were characterized by field emission scanning electron microscope (FESEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. The absence of COOH peak in GO and GP specimen found in the XPS and FTIR confirm the partial reduction of GO by oxidative decarboxylation during the EPD. The shift in the >NCO bond to a higher binding energy, as compared to the pure PVP, indicated the presence of intermolecular hydrogen bonding between the PVP and GO. The antibacterial activity of the coated specimens using marine bacterial isolates of Gram-negative Pseudomonas sp. and Gram-positive Bacillus sp. showed a four order reduction in bacterial density, and a significant decrease in the biofilm thickness on the GP specimens. The enhanced antibacterial activity was due to the disruption of cell membranes by sharp edges of GO surface and oxidative stress imparted due to reactive oxygen species. The enhanced surface hydration by PVP inhibited the adhesion and growth of organic molecules on GP coating. Further, the enhanced photocatalytic activity of GO due to the presence of PVP also increased the generation of H2O2 in GP coatings as compared to GO coating. These results show that GP composite coating is a promising candidate to tailor 316L SS surface with excellent antibacterial and anti-biofouling properties.