Inorganic Nanomaterials with Intrinsic Singlet Oxygen Generation for Photodynamic Therapy

Abstract

Inorganic nanomaterials with intrinsic singlet oxygen (1O2) generation capacity, are emerged yet dynamically developing materials as nano‐photosensitizers (NPSs) for photodynamic therapy (PDT). Compared to previously reported nanomaterials that have been used as either carriers to load organic PSs or energy donors to excite the attached organic PSs through a Foster resonance energy transfer process, these NPSs possess intrinsic 1O2 generation capacity with extremely high 1O2 quantum yield (e.g., 1.56, 1.3, 1.26, and 1.09) than any classical organic PS reported to date, and thus are facilitating to make a revolution in PDT. In this review, the recent advances in the development of various inorganic nanomaterials as NPSs, including metal‐based (gold, silver, and tungsten), metal oxide‐based (titanium dioxide, tungsten oxide, and bismuth oxyhalide), metal sulfide‐based (copper and molybdenum sulfide), carbon‐based (graphene, fullerene, and graphitic carbon nitride), phosphorus‐based, and others (hybrids and MXenes‐based NPSs) are summarized, with an emphasis on the design principle and 1O2 generation mechanism, and the photodynamic therapeutic performance against different types of cancers. Finally, the current challenges and an outlook of future research are also discussed. This review may provide a comprehensive account capable of explaining recent progress as well as future research of this emerging paradigm.

Progress of Nanomaterials in Photodynamic Therapy Against Tumor

“…Au NPs have surface plasmon resonance (SPR), chemical inertness and excellent biocompatibility, which are mainly used as passivation agents, drug delivery agents, imaging agents, and photothermal agents, which have different characteristic shapes, such as particles, rod-shaped, cluster-shaped, shell-shaped, spike-shaped and star, etc., ( Younis et al, 2021 ). In PDT, gold nanoparticles can be used alone or as part of a multifunctional nanomaterial hybrid system for PSs delivery.…”

“…Ag NPs have higher 1 O 2 yield than Au NPs and Pt NPs due to stronger SPR ( Younis et al, 2021 ). Inspired by the ability of ICD to transform tumors from cold to heat by inducing tumor cells to release tumor antigens and damage-associated molecular patterns (DAMPs) and then enhance T cell proliferation and infiltration ( Xu et al, 2022 ).…”

“…Metal oxide nanomaterials have found promising biomedical applications for fluorescent labeling due to the advantages of high photostability, large extinction coefficient, high emission quantum yield and easy surface modification ( Younis et al, 2021 ). In view of the fact that nano-heterostructures can promote photo-induced electron-hole separation and the generation of ROS, 2D nano-heterostructure-based PSs can provide a major advancement in PDT.…”

Photodynamic Therapeutic Effect of Nanostructured Metal Sulfide Photosensitizers on Cancer Treatment

“…Currently, there are active research in progress in the field of nanotechnology in developing PSs with greater tumor selectivity, enhanced hydrophilicity, and strong photosensitivity to yield a reliable photodynamic reaction. The studies show that metal nanoparticles such as gold, silver and copper, manganese, aluminum nanoparticles; organic–inorganic hybrid nanoparticles, metal oxide nanoparticles, metal sulfide nanoparticles, Cd-free nanostructured metal chalcogenides (NMCs) have been extensively investigated in PDT [ 22 – 25 ]. While nanoparticles surface endows increased chemical activity, they require relatively low-power radiation to lead photo-stimulated reaction to generate singlet oxygen [ 26 ].…”

Reactive Oxygen Species and Folate Receptor-Targeted Nanophotosensitizers Composed of Folic Acid-Conjugated and Poly(ethylene glycol)-Chlorin e6 Tetramer Having Diselenide Linkages for Targeted Photodynamic Treatment of Cancer Cells

“…In particular, nanophotosensitizers, which are photosensitizer-incorporated nano-sized carriers, have been suggested as an ideal candidate for PDT [ 12 , 13 , 14 ]. Various biocompatible polymers or nanomaterials such as natural polysaccharides, dendrimers, iron oxide nanoparticles and synthetic polymers have been investigated to fabricate nanophotosensitizers [ 12 , 13 , 14 , 15 , 16 ]. Chin et al reported that poly(vinylpyrrolidone) (PVP)-Ce6 formulations accelerate the tumor accumulation of photosensitizers and show fast clearance from the skin of nude mice [ 11 ].…”