Bandgap-Engineered Germanene Nanosheets as an Efficient Photodynamic Agent for Cancer Therapy.

Two-dimensional (2D) monoelemental materials (Xenes) show considerable potential in bioapplications owing to their unique 2D physicochemical features and the favored biosafety resulting from their monoelemental composition. However, the narrow band gaps of Xenes prevent their broad applications in biosensors, bioimaging and phototherapeutics. In this study, it is demonstrated that 2D germanene terminated with -H via surface chemical engineering, shows a much broadened direct band gap of 1.65 eV, which enables the material to be used as a novel inorganic photosensitizer for the photodynamic therapy of singlet oxygen. Through theoretical analysis and in vitro studies, H-germanene nanosheets demonstrate a substantially enlarged band gap and favorable biodegradability, demonstrating a substantial cancer treatment capacity. This study demonstrates the feasibility of constructing novel therapeutic photodynamic agents by surface covalent engineering for catalytic tumor therapy.