Functionalized ZnS quantum dots as cancer theranostics: A cornerstone for precision onco-targeting

Cancer is among the leading causes of death globally. Early diagnosis and therapy provide cancer patients with the highest chance of survival. Despite recent significant advances in understanding the complex pathways that contribute to cancer progression and metastasis, researchers are still unable to adequately treat cancer progressing to many crucial organs. As cancer cells and tumor microenvironments are highly complex, the mechanisms of tumor invasion, tumor development, and metastasis remain incompletely understood. Therefore, to grasp the complex molecular information behind biological behavior of tumors, novel technologies for cancer detection and real-time observation are urgently needed. Quantum dots (QDs) are indeed luminous semiconductor materials in the nanometric size range. Considering their unique optical traits including excellent luminescence, simultaneous acquisition of numerous signals, stability over time, and tunable emission spectra, QDs are appealing as possible cancer theranostic devices. Zinc sulfide (ZnS) QDs are frequently employed as a cornerstone for precision onco-targeting owing to their high quantum yield, low toxicity, biocompatibility, and versatility for diverse surface modifications. ZnS QDs are now showing great promise for cancer bioimaging and anticancer drug delivery. The present review describes the frontiers of surface modifications and theranostic applications of ZnS QDs in the treatment of various cancers.