Surface Engineering of MoS2 Quantum Dots via Cyclodextrin-Based Host-Guest Chemistry as Versatile Platforms for Enhanced Cell Imaging Application

Transition metal chalcogenide quantum dots (QDs), especiallyMoS(2) QDs, are an emerging class of novel optical probesfor versatilebioanalytical applications owing to their distinct physicochemicalproperties. However, the reasonable use of these QDs for biologicalimaging has been largely restricted due to the challenge of controllablesurface functionalization. In this work, we report a new strategyto engineer the surface of MoS2 QDs by taking advantageof cyclodextrin (CD)-based host-guest chemistry. The prepared beta-CD-modified QDs (beta-CD-MoS2 QDs) exhibit enhancedfluorescence properties, excellent biocompatibility, and good stability,making them promising as novel optical probes for bioimaging. Cellularimaging experiments revealed that these beta-CD-MoS2 QDs can enter living cells through multiple internalization pathways,which differs significantly from pristine QDs. Particularly, we observedthat the intracellular accumulation of MoS2 QDs in lipiddroplets was enhanced owing to the specific binding of beta-CDto cholesterol, which was then harnessed for monitoring the lipidmetabolism in living cells via fluorescence imaging. Furthermore,we also demonstrated the potential use of beta-CD-MoS2 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 surfaceof MoS2 QDs and other analogous materials via CD-basedhost-guest chemistry for advancing their cell imaging applications.