Redox Polymers for Drug Delivery
During recent years the number of publications on redox polymers in relation to cancer therapy has been overwhelming. This is very significant since the development of these polymers as controlled-release systems of drugs and genetic material has represented a major achievement. They contain functional groups that respond to the different redox potentials existing in the microenvironments of the tumor cells. Thus, high concentrations of glutathione or reactive oxygen species are present in the endosome of such cells. From redox polymers, micellar, hydrogel and hollow vesicle nanosystems can be obtained. These are able to uptake the drug and release it in the target organ or tissue selectively, in response to the redox stimulus. Among the newest systems are mesoporous materials and metal–organic frameworks, which can not only respond to multiple endogenous stimuli but also to exogenous stimuli and support high drug-loading capacity. In addition, being easily functionalized and displaying good degradability and biocompatibility is an extra bonus.