Issue 21, 2023

Recent advances in type I organic photosensitizers for efficient photodynamic therapy for overcoming tumor hypoxia

Abstract

Photodynamic therapy (PDT) with an oxygen-dependent character is a noninvasive therapeutic method for cancer treatment. However, its clinical therapeutic effect is greatly restricted by tumor hypoxia. What's more, both PDT-mediated oxygen consumption and microvascular damage aggravate tumor hypoxia, thus, further impeding therapeutic outcomes. Compared to type II PDT with high oxygen dependence and high oxygen consumption, type I PDT with less oxygen consumption exhibits great potential to overcome the vicious hypoxic plight in solid tumors. Type I photosensitizers (PSs) are significantly important for determining the therapeutic efficacy of PDT, which performs an electron transfer photochemical reaction with the surrounding oxygen/substrates to generate highly cytotoxic free radicals such as superoxide radicals (˙O2) as type I ROS. In particular, the primary precursor (˙O2) would progressively undergo a superoxide dismutase (SOD)-mediated disproportionation reaction and a Haber–Weiss/Fenton reaction, yielding higher cytotoxic species (˙OH) with better anticancer effects. As a result, developing high-performance type I PSs to treat hypoxic tumors has become more and more important and urgent. Herein, the latest progress of organic type I PSs (such as AIE-active cationic/neutral PSs, cationic/neutral PSs, polymer-based PSs and supramolecular self-assembled PSs) for monotherapy or synergistic therapeutic modalities is summarized. The molecular design principles and strategies (donor–acceptor system, anion–π+ incorporation, polymerization and cationization) are highlighted. Furthermore, the future challenges and prospects of type I PSs in hypoxia-overcoming PDT are proposed.

Graphical abstract: Recent advances in type I organic photosensitizers for efficient photodynamic therapy for overcoming tumor hypoxia

Article information

Article type
Review Article
Submitted
15 Mär 2023
Accepted
26 Apr 2023
First published
28 Apr 2023

J. Mater. Chem. B, 2023,11, 4600-4618

Recent advances in type I organic photosensitizers for efficient photodynamic therapy for overcoming tumor hypoxia

B. Lu, L. Wang, H. Tang and D. Cao, J. Mater. Chem. B, 2023, 11, 4600 DOI: 10.1039/D3TB00545C

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