Abstract
Reactive oxygen species (ROS) play an important role in signal transduction and metabolism. Over‐produced ROS in cells or tissues, however, often leads to oxidation stress that has implications in a series of diseases including cancer, aging, atherosclerosis and inflammation. Driven by the need for on‐demand drug delivery and fuelled by recent development of ROS‐responsive materials and nanomedicine, responsive drug delivery systems (DDSs) have gained increasing research interest. ROS‐responsive DDS is designed to release therapeutic agents only in targets of interest that produce excessive ROS, which may lead to both enhanced therapeutic efficiency and reduced side effects. Multiple‐stimuli responsive DDSs that are also sensitive to other stimuli can further enhance controlled drug release in sites where multiple stimuli coexist. Beyond drug delivery, multifunctional DDSs have great potential in achieving simultaneous imaging, combinatorial therapy and targeting ability by introducing multifunctional elements such as signal reporter, targeting elements and photosensitizer. This review will summarize the latest development of ROS‐responsive DDSs and discuss their design principle and biomedical applications.
Highlights
Tremendous efforts have been devoted for the development of drug delivery systems (DDSs) that can effectively deliver therapeutic agents into disease sites
The results indicate the combined effect of photodynamic therapy (PDT) and Reactive oxygen species (ROS)-triggered drug delivery that contribute to the enhanced therapeutic efficiency
Among the many internal stimuli, ROS represents a unique signature for many pathological conditions, making it an attractive trigger for drug release
Summary
Tremendous efforts have been devoted for the development of drug delivery systems (DDSs) that can effectively deliver therapeutic agents into disease sites. In a typical ROS and pH dual-responsive system, the pH responsive elements generally improve drug release by inducing a morphology change of the drug carrier upon protonation or deprotonation Based on this strategy, a ROS and pH dual-responsive system was reported for drug delivery to inflammatory areas with oxidative stress and reduced pH conditions.[51] The DDS involves a Cy3-labelled pH-responsive N-palmitoyl chitosan (NPCS) which forms NP with a polythioketal and therapeutic agent curcumin (Figure 5A). Another example of ROS and thermal dual-responsive DDS was reported by Chen’s group.[61] The triblock polymer consists of alternating polyethylene glycol (PEG) as the shell and a thermal and oxidation dual-responsive thioether containing polymer as the core The hydrophobic drugs such as Nile red are encapsulated into the collapsed carrier at elevated temperature and released upon ROS exposure.
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