Given the increasing evidence indicates that many pathological conditions are associated with elevated reactive oxygen species (ROS) levels, there have been growing research efforts focused on the development of ROS‐responsive carrier systems because of their promising potential to realize more specific diagnosis and effective therapy. By judicious utilization of ROS‐responsive functional moieties, a wide range of carrier systems has been designed for ROS‐mediated drug delivery. In this review article, insights into design principle and recent advances on the development of ROS‐responsive carrier systems for drug delivery applications are provided alongside discussion of their in vitro and in vivo evaluation. In particular, the discussions in this article will mainly focus on polymeric nanoparticles, hydrogels, inorganic nanoparticles, and activatable prodrugs that have been integrated with diverse ROS‐responsive moieties for spatiotemporally controlled release of drugs for effective therapy.

Graphene oxide has unique physiochemical properties, showing great potential in biomedical applications. In the present work, functionalized reduced graphene oxide (PEG-BPEI-rGO) has been developed as a nanotemplate for photothermally triggered cytosolic drug delivery by inducing endosomal disruption and subsequent drug release. PEG-BPEI-rGO has the ability to load a greater amount of doxorubicin (DOX) than unreduced PEG-BPEI-GO via π-π and hydrophobic interactions, showing high water stability. Loaded DOX could be efficiently released by glutathione (GSH) and the photothermal effect of irradiated near IR (NIR) in test tubes as well as in cells. Importantly, PEG-BPEI-rGO/DOX complex was found to escape from endosomes after cellular uptake by photothermally induced endosomal disruption and the proton sponge effect, followed by GSH-induced DOX release into the cytosol. Finally, it was concluded that a greater cancer cell death efficacy was observed in PEG-BPEI-rGO/DOX complex-treated cells with NIR irradiation than those with no irradiation. This study demonstrated the development of the potential of a PEG-BPEI-rGO nanocarrier by photothermally triggered cytosolic drug delivery via endosomal disruption.

Graphene oxide (GO) has attracted an increasing amount of interest because of its potential applications in biomedical fields such as biological imaging, molecular imaging, drug/gene delivery, and cancer therapy. Moreover, GO could be fabricated by modifying its functional groups to impart specific functional or structural attributes. This study demonstrated the development of a GO-based efficient gene delivery carrier through installation of polyethylenimine, a cationic polymer, which has been widely used as a nonviral gene delivery vector. It was revealed that a hybrid gene carrier fabricated by conjugation of low-molecular weight branched polyethylenimine (BPEI) to GO increased the effective molecular weight of BPEI and consequently improved DNA binding and condensation and transfection efficiency. Furthermore, this hybrid material facilitated sensing and bioimaging because of its tunable and intrinsic electrical and optical properties. Considering the extremely high transfection efficiency comparable to that of high-molecular weight BPEI, high cell viability, and its application as a bioimaging agent, the BPEI-GO hybrid material could be extended to siRNA delivery and photothermal therapy.

Capture and release: The material‐independent surface chemistry of a poly(norepinephrine) (pNE) which exhibits perfect smoothness at the nanometer scale is controlled by 3,4‐dihydroxybenzaldehyde‐norepinephrine (DHBA‐NE) conjugates. The pNE layer containing DHBA‐NE serves to store and release small therapeutics such as nitric oxide.