Research progress in endogenous H 2 S‐activatable nanoplatforms for cancer theranostics

Hydrogen sulfide (H 2 S) is a critical signaling molecule that exists in a wide variety of organizational categories, which has significant influences on several physiological functions containing vasodilatory modulation and neurotransmitter regulation. Dysregulated production and abnormal contents of H 2 S are considered to be the characteristics of different types of disease occurrence; the detection and real‐time monitoring of endogenous H 2 S in tissues and living cells is of great significance. However, most conventional H 2 S detection methods still suffer from some inevitable drawbacks including low bioavailability, accuracy, and sensitivity, making them difficult to apply in visualizing endogenous H 2 S in vivo. Optical probes constructed with the features of fast responsive time, excellent selectivity and sensitivity, as well as noninvasive performance, providing the possibility of detecting and monitoring H 2 S in real‐time at the cellular and mouse levels. Such methods show the application prospect, which could avoid the defects of conventional detection approaches. Furthermore, a certain concentration of H 2 S can influence the therapeutic efficacy, for example, anti‐inflammation and protection against oxidative stress, during the treatment of cancer and neurodegenerative diseases. Because the generation of overexpressed exogenous H 2 S is closely tied to the tumor formation, the development of H 2 S‐responsive theranostic nanoplatforms is highly needed for H 2 S‐related tumor diagnosis and treatment. The theranostic nanoplatforms are expected to maximize therapeutic effectiveness and minimize side effects to normal tissues. In this review article, the current research progress, challenges, and future possibilities of H 2 S‐activatable nanoplatforms for H 2 S detection and malignant tumor theranostics are summarized.