Tunable Fabrication of Molybdenum Disulfide Quantum Dots for Intracellular MicroRNA Detection and Multiphoton Bioimaging

Molybdenum disulfide (MoS 2 ) quantum dots (QDs) (size <10 nm) possess attractive new properties due to the quantum confinement and edge effects as graphene QDs. However, the synthesis and application of MoS 2 QDs has not been investigated in great detail. Here, a facile and efficient approach for synthesis of controllable‐size MoS 2 QDs with excellent photoluminescence (PL) by using a sulfuric acid‐assisted ultrasonic route is developed for this investigation. Various MoS 2 structures including monolayer MoS 2 flake, nanoporous MoS 2 , and MoS 2 QDs can be yielded by simply controlling the ultrasonic durations. Comprehensive microscopic and spectroscopic tools demonstrate that the MoS 2 QDs have uniform lateral size and possess excellent excitation‐independent blue PL. The as‐generated MoS 2 QDs show high quantum yield of 9.65%, long fluorescence lifetime of 4.66 ns, and good fluorescent stability over broad pH values from 4 to 10. Given the good intrinsic optical properties and large surface area combined with excellent physiological stability and biocompatibility, a MoS 2 QDs‐based intracellular microRNA imaging analysis system is successfully constructed. Importantly, the MoS 2 QDs show good performance as multiphoton bioimaging labeling. The proposed synthesis strategy paves a new way for facile and efficient preparing MoS 2 QDs with tunable‐size for biomedical imaging and optoelectronic devices application.