Upconversion luminescent sensor for endogenous H2O2 detection in cells based on the inner filter effect of coated silver layer

We design and construct an upconversion luminescence sensor for hydrogen peroxide detection based on lanthanide-doped nanoparticles (LDN-OA). After modification with an electron-donating ligand, the silver was coated on the surface of LDN-OA in-situ by photo-induced free-electron reduction under the excitation of ultraviolet light. Then, the core-shell structure of upconversion nanoparticles growing with the silver metal surface is formed and modified with polyethylene-glycol, leading to the final hydrogen peroxide biosensor (denoted as LDN@Ag-PEG). The sensor is constructed based on the luminescence inner filter effect, using the LDN-OA as an energy donor and the coated silver layer as an energy acceptor. The confocal images were analyzed in vitro as well, presenting that the LDN@Ag-PEG sensor could achieve the sensing of endogenous hydrogen peroxide under 980 nm excitation. Thus the upconversion luminescence sensor provides a powerful idea for the development of intracellular biomolecule sensors upon near-infrared light irradiation as well.