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

Highlights • UCNPs-MoS 2 nanoassemblies were developed to detect reactive oxygen species (ROS) with a fast response time. • The nanoprobe had been successfully applied in the imaging of exogenous and endogenous ROS in living cells. • The nanoprobe was employed in in vivo visualization of ROS level in zebrafish. Abstract 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)-MoS 2 nanoflakes. In this nanostructure, the positively charged UCNPs could assemble with negatively charged poly(acrylic acid) modified MoS 2 nanoflakes by electrostatic force, which led to the remarkable fluorescence quenching of UCNPs owing to the excellent quenching ability of MoS 2 nanoflakes. In contrast, in the presence of ROS, the fluorescence recovery of UCNPs is successfully realized owing to the decomposition of MoS 2 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-MoS 2 nanoflakes has been successfully used for ROS bioimaging in cells and zebrafish. [ABSTRACT FROM AUTHOR]