Singlet oxygen storage and controlled release for improving photodynamic therapy against hypoxic tumor

Abstract

Photodynamic therapy (PDT) has been considered to become a promising tumor treatment method due to its non-invasiveness and low-risk. However, there are two factors that will affect the therapy efficacy. One is the light source and the other is the tumor hypoxia. Therefore, one emerging PDT strategy has been developed to break these limits. This strategy is to adopt the compounds such as 2-pyridone, anthracene and naphthalene derivatives with the ability of the storage and controlled release of singlet oxygen (1O2) to achieve PDT in the dark. In this review, we focused on the construction strategy of integrated antitumor drugs containing these 1O2 storage/release units and photosensitizers, and summarized their PDT performance in hypoxic tumor or in the dark. The methods to integrate these compounds with photosensitizers or nanocarriers were discussed in detail, which will provide insightful design guidelines for future design of highly efficient antitumor systems based on 1O2 storage and controlled release.