Reactive oxygen species generating systems meeting challenges of photodynamic cancer therapy

Abstract

Reactive oxygen species (ROS)-mediated mechanism is the major cause underlying the efficacy of photodynamic therapy (PDT). The PDT procedure is based on the cascade of synergistic effects between light, photosensitizer (PS) and oxygen, which greatly favor the spatiotemporal control of the treatment. This procedure has also evoked several unresolved challenges at different levels including (i) limited penetration depth of light restricts traditional PDT to only superficial tumours; (ii) oxygen reliance deprives PDT treatment of hypoxic tumours; (iii) light could complicate the phototherapeutic outcomes due to the concurrent heat generation; (iv) specific delivery of PSs to sub-cellular organelles for exerting effective toxicity remains an issue; and (v) side effects by undesirable white-light activation and self-catalysation of traditional PSs. Recent advances in nanotechnology and nanomedicine have provided new opportunities to develop ROS-generating systems through photodynamic or non-photodynamic procedures while tackling the challenges of current PDT approaches. In this review, we summarize the current status and discuss the possible opportunities of ROS generation for cancer therapy. We hope this review will spur pre-clinical research and clinical practice for ROS-mediated tumour treatment.

Synthesis of Film‐Forming Photoactive Latex Particles by Emulsion Polymerization–Induced Self‐Assembly to Produce Singlet Oxygen

“…Waterborne latexes synthesized by emulsion polymerization, widely present in the coating industry for different applications ranging from waterborne paints, inks, adhesives, paper coating, protective coating or binders for food packaging, and textiles, elicit increasing interest for production of high added value innovative products. Production of singlet oxygen ( 1 O 2 ), a selective reactive oxygen species (ROS) by irradiation under visible light of organic photosensitizers ( Sens ), has attracted increasing interest in the fields of fine chemistry, photo‐decontamination of air/water, antimicrobial materials, or photodynamic therapy (PDT) . Singlet oxygen, a powerful oxidant produced by energy transfer from the photoactivated sensitizer to oxygen, induces specific oxidation reactions of organic molecules to produce, for instance, pharmaceutical ingredients like artemisinin .…”

Nanoparticle design strategies for enhanced anticancer therapy by exploiting the tumour microenvironment

“…174, 175 The PS can generate reactive oxygen species (ROS) from oxygen to kill cells under light activation at specific wavelength. 176 However, the application of PDT is limited by the hypoxia condition in tumours. To enhance the PDT efficacy, it is highly desirable to selectively heighten the local oxygen level in the tumour area.…”

Monodispersed Copper(I)‐Based Nano Metal–Organic Framework as a Biodegradable Drug Carrier with Enhanced Photodynamic Therapy Efficacy

“…[24] Moreover, it is attractive that CuTz-1 exhibits continuous absorption from visible to near-infrared (NIR) region ( Figure S1, Supporting Information), which can be attributed to the intervalence charge-transfer bands (IVCT) and the d-d transition. [14][15][16] Thus, the CuTz-1 MOF has great potential for the application of type I PDT under NIR laser excitation. The absorption in the NIR region by CuTz-1 could be related to the IVCT band involving Cu I to Cu II within the polymeric structure.…”