Redox-sensitive smart nanosystems for drug and gene delivery

Background: Smart stimulus-responsive nanocarriers represent a rapidly growing class of drug-delivery systems for cancer and other diseases. Objective: The alterations of redox potential between the intracellular environment and the extracellular space have been widely utilized as a trigger for delivery of therapeutic agents by smart stimulus-responsive nanocarriers. We set out to review the scientific literature. Method: Published papers between 1980 and the present day were surveyed. Results: The advantages of redox-activated smart delivery of drugs, genes, and imaging agents include: the amplitude of the redox-responsive signal; the simple chemical features needed to trigger the activation process; and the relative simplicity of preparing these nanocarriers with an integrated redox-sensitive triggering element. Redox-sensitive nanovehicles are often sensitive to glutathione (GSH) as a regulator of cellular redox potential, which is a very important redox couple in mammalian cells. Other nanostructures can be designed to respond to oxidation, which may be useful for drug-delivery to sites with oxidative stress. Conclusion: Redox-responsive nanocarriers are a prominent member of the class of smart nanocarriers, and are expected to grow importance in coming years.