Upconversion nanoparticles-MoS2 nanoassembly as a fluorescent turn-on probe for bioimaging of reactive oxygen species in living cells and zebrafish

Nanoassemblies for bioimaging in living cells have attracted much attention. In this work, an efficient and sensitive turn-on fluorescent detection platform for reactive oxygen species (ROS) in living cells has been constructed using the nanoassemblies of upconversion nanoparticles (UCNPs)-MoS2 nanoflakes. In this nanostructure, the positively charged UCNPs could assemble with negatively charged poly(acrylic acid) modified MoS2 nanoflakes by electrostatic force, which led to the remarkable fluorescence quenching of UCNPs owing to the excellent quenching ability of MoS2 nanoflakes. In contrast, in the presence of ROS, the fluorescence recovery of UCNPs is successfully realized owing to the decomposition of MoS2 nanoflakes through the chemical reaction with ROS. The ROS-mediated disassembly of the nanoarchitecture display excellent fluorescent response toward ROS. Furthermore, the disassembly of UCNPs-MoS2 nanoflakes has been successfully used for ROS bioimaging in cells and zebrafish.