ROS-responsive Tellurium-containing Polymers

Stimuli-responsive polymers are defined as polymers whose structure and properties can be changed in response to minor changes in the surrounding physical or chemical environment and have become increasingly attractive as biomaterials. Reactive oxygen species (ROS) are a series of chemically reactive oxygen-containing molecules, which play an indispensable physiological role in cell signal transduction, acting as secondary messengers. It has been suggested that ROS levels in the cancer cells are much higher than those in the normal cells, and thus, ROS have been selected as a starting point or target for cancer therapy. Tellurium belongs to the chalcogen along with sulfur and selenium. Compared to sulfur and selenium, the relatively large atomic size and low electronegativity of tellurium give it many unique properties, such as redox sensitivity and coordination ability. In recent years, our research group pioneered in the research of ROS-responsive tellurium-containing polymers and their application in drug delivery. The work presented in this feature article, starting from the difference of oxidation responsiveness of tellurium and selenium, explored the ultra-sensitive ROS-response of tellurides. Then we studied the application of tellurium-containing polymers in drug delivery, focusing on the delivery of platinum drugs. For example, polymers with tellurium in the main chain can simultaneously deliver Cisplatin and indocyanine green to achieve a combination of cancer chemotherapy and photodynamic therapy, while side-chain tellurium/platinum-containing polymer can realize a combination of cancer chemotherapy and radiotherapy. Besides, the tellurium/platinum assembly can achieve controlled drug release through a dual response mechanism of ROS and coordination. Finally, we put forward the prospect of the development of tellurium-containing polymers, such as the development of controllable synthesis of tellurium-containing polymers based on chain polymerization, the development of tellurium-containing polymers and tellurium/platinum-containing assembly with different topological structures, and the exploration of the long-term toxicity of tellurium-containing molecules in biological applications.