Recent progress in augment of reactive species with nanoplatforms for cancer therapy

Reactive species (RS), mainly including reactive oxygen species (ROS) and reactive nitrogen species (RNS), are indispensable in a wide variety of biological processes. RS often have elevated levels in cancer cells and tumor microenvironment. They also have a dual effect on cancer, on the one hand promoting pro-tumorigenic signaling to facilitate tumor survival, and on the other hand promoting antitumorigenic pathway to induce cell death. Excessive RS would disrupt cellular redox homeostasis balance and show partiality as oxidants, which would cause irreversible damage to adjacent biomolecules, such as lipids, proteins and nucleic acids. The altered redox environment and corresponding increased antioxidant capacity in cancer cells render the cells susceptibile to RS-manipulated therapies, especially augment of RS. With the rapid development of nanotechnology and nanomedicine, a large number of cancer therapeutic nanoplatforms have been developed to trigger RS overproduction by exogenous and/or endogenous stimulation. In this review, we highlight lastest progresses in the nanoplatforms designed for ugment of RS in cancer therapy. The nanoplatforms based on the strategies including disability of antioxidant defense system, photodynamic therapy (PDT), sonodynamic therapy (SDT), and chemodynamic therapy (CDT) are introduced. The crucial obstacles involved in these strategies, such as light penetration limitation of PDT, ralatively low RS release by SDT, and strict conditions of Fenton reaction- mediated CDT are also discussed, and the feasible solutions for improvement are proposed. Furthermore, synergistic therapies among individual therapeutic modalities, such as chemotherapy, photothermal therapy, RS-based dynamic therapies are overviewed, which contribute to achieve a more optimal anticancer efficacy than linear addition. This review would shed light on the development of non-invasive cancer therapy based on RS manipulation, and provide guidance for establishing promising cancer therapeutic platforms in clinic.