Titania nanotubes with aminated reduced graphene oxide as efficient photocatalysts for antibacterial application under visible light
Kyoung-Suk Moon, Ji‐Myung Bae, Eun Joo Choi, Seunghan Oh
Abstract
Titania and reduced graphene oxide (rGO) are well-known materials with excellent photocatalytic properties, but research on the photocatalytic-based antibacterial effects of their combination remains limited. This study explored the suitability of titania nanotubes (TiO 2 NTs) combined with rGO and two terminal functional groups (nonfunctional and aminated groups (NH 2 )) as efficient photocatalysts for antimicrobial applications under visible light irradiation. Field-emission scanning electron microscopy observations revealed that rGO covered the entire surface of the TiO 2 NTs. Tauc plots calculated from the spectra of diffuse reflectance spectroscopy showed that the band gaps of the nonfunctional and amine functional groups of rGO-coated TiO 2 NTs were 2.40 and 2.21 eV, respectively. Therefore, all rGO-coated TiO 2 NTs exhibited photocatalytic activity under 470 nm visible light irradiation. An antibacterial colony forming unit test using S. aureus and P. aeruginosa , and two enzymatic activity tests (superoxide dismutase and catalase) on the same bacteria, showed that the aminated rGO-coated TiO 2 NTs showed excellent antibacterial activity under 470 nm visible-light irradiation compared to nonfunctional rGO-coated TiO 2 NTs and uncoated TiO 2 NTs groups. In addition, the MTT assay showed that the aminated rGO-coated TiO 2 NTs enhanced cell viability after visible light irradiation. Therefore, the combination of aminated rGO-coated TiO 2 NTs and visible-light-triggered photocatalytic activity has significant potential for expressing antibacterial properties in dental applications.