6‐Mercaptopurine‐Induced Fluorescence Quenching of Monolayer MoS2 Nanodots: Applications to Glutathione Sensing, Cellular Imaging, and Glutathione‐Stimulated Drug Delivery

Abstract

AbstractMolybdenum disulfide (MoS2) nanodots (NDs) with sulfur vacancies have been demonstrated to be suitable to conjugate thiolated molecules. However, thiol‐induced fluorescence quenching of MoS2 NDs has been rarely explored. In this study, 6‐mercaptopurine (6‐MP) serves as an efficient quencher for the fluorescence of monolayer MoS2 (M‐MoS2) NDs. 6‐MP molecules are chemically adsorbed at the sulfur vacancy sites of the M‐MoS2 NDs. The formed complexes trigger the efficient fluorescence quenching of the M‐MoS2 NDs due to acceptor‐excited photoinduced electron transfer. The presence of glutathione (GSH) efficiently triggers the release of 6‐MP from the M‐MoS2 NDs, thereby switching on the fluorescence of the M‐MoS2 NDs. Thus, the 6‐MP‐M‐MoS2 NDs are implemented as a platform for the sensitive and selective detection of GSH in erythrocytes and live cells. Additionally, thiolated doxorubicin (DOX‐SH)‐loaded M‐MoS2 NDs (DOX‐SH/M‐MoS2 NDs) serve as GSH‐responsive nanocarriers for DOX‐SH delivery. In vitro studies reveal that the DOX‐SH/M‐MoS2 NDs exhibit efficient uptake by HeLa cells and greater cytotoxicity than free DOX‐SH and DOX. In vivo study shows that GSH is capable of triggering the release of DOX‐SH from M‐MoS2 ND‐based nanomaterials in mice. It is revealed that the DOX‐SH/M‐MoS2 NDs can be implemented for simultaneous drug delivery and fluorescence imaging.