Ratiometric fluorescent sensor based on MoS2 QDs and AuNCs for determination and bioimaging of alkaline phosphatase.

Abstract Herein, a ratiometric fluorescent sensor based on MoS2 quantum dots (QDs) and glutathione-capped gold nanoclusters (AuNCs) was developed for determination and imaging of alkaline phosphatase (ALP). The sensor was developed by covalently linking QDs with AuNCs to form stable MoS2@AuNCs nanohybrids that exhibited the blue fluorescence of MoS2 QDs and the red fluorescence of AuNCs. In the presence of Ce3+, the fluorescence intensity of AuNCs was increased due to the aggregation-induced emission enhancement (AIEE), while that of MoS2 QDs remained unchanged, thus could be used as a reference signal. After adenosine 5′-monophosphate (AMP) and ALP were introduced into the system, AMP was hydrolyzed to adenosine and phosphate ions (PO43−). Owing to higher affinity between Ce3+ and PO43−, the AIEE effect was inhibited, in turn resulting in the decrease of AuNCs fluorescence. The developed ratiometric fluorescent sensor had a linear response to ALP concentration ranging from 0.5 to 50 U L−1 with a detection limit (LOD) of 0.08 U L−1. Moreover, the sensor had low cytotoxicity and was successfully employed in lysosome localization and bioimaging of intracellular ALP in living cells.