Surface Engineering of MoS Quantum Dots via Cyclodextrin-Based Host-Guest Chemistry as Versatile Platforms for Enhanced Cell Imaging Application.

Transition metal chalcogenide quantum dots (QDs), especially MoS QDs, are an emerging class of novel optical probes for versatile bioanalytical applications owing to their distinct physicochemical properties. However, the reasonable use of these QDs for biological imaging has been largely restricted due to the challenge of controllable surface functionalization. In this work, we report a new strategy to engineer the surface of MoS QDs by taking advantage of cyclodextrin (CD)-based host-guest chemistry. The prepared β-CD-modified QDs (β-CD-MoS QDs) exhibit enhanced fluorescence properties, excellent biocompatibility, and good stability, making them promising as novel optical probes for bioimaging. Cellular imaging experiments revealed that these β-CD-MoS QDs can enter living cells through multiple internalization pathways, which differs significantly from pristine QDs. Particularly, we observed that the intracellular accumulation of MoS QDs in lipid droplets was enhanced owing to the specific binding of β-CD to cholesterol, which was then harnessed for monitoring the lipid metabolism in living cells via fluorescence imaging. Furthermore, we also demonstrated the potential use of β-CD-MoS QDs for targeted cell imaging and microplate-based cell recognition, which can be easily achieved via bioconjugation with functional motifs (e.g., folate acid) through host-guest chemistry. Altogether, these results illustrate the great potential of engineering the surface of MoS QDs and other analogous materials via CD-based host-guest chemistry for advancing their cell imaging applications.