Beyond External Light: On-Spot Light Generation or Light Delivery for Highly Penetrated Photodynamic Therapy

Abstract

External light sources, such as lasers, light emitting diodes (LEDs) and lamps, are widely applied in photodynamic therapy (PDT); however, their use is severely limited by the nature of shallow tissue penetration depth. The recent exploration of light delivery or local generation on tumor sites has attracted much attention, owing to the fact that these systems are significantly endowed with high tissue penetration. In this review, we briefly introduced the principle of "onspot light generation or delivery systems" in PDT. These systems are divided into different categories: (1) implantable luminescence, (2) mechanoluminescence, (3) electrochemiluminescence, (4) Cerenkov luminescence, (5) chemiluminescence, and (6) bioluminescence. Finally, their applications, advantages, and disadvantages in PDT will be appropriately summarized and further discussed in detail. We believe that this review will provide general guidance for the further design of light generation or delivery systems and clinical studies for PDT-mediated cancer treatments with unparalleled merits.

Wireless Powered Microwave-Light Conversion Platform with Dual-Stimulus Nanoresponder Coating for Deep-Seated Photodynamic Therapy

“…Therefore, we conjecture that external MW can be converted into internal visible light, achieving high-yield ROS through MW induction (we refer to this strategy as MW-induced photodynamic therapy, which is abbreviated as mw-PDT). Unlike conventional external field-assisted therapy that has only a single stimulus source, − mw-PDT includes both MW and light. Therefore, selecting a dual-source responsive agent that responds to both light and MW can enable the coupling of MW-therapy and phototherapy, resulting in better therapeutic effects than conventional external field-assisted therapy.…”

Engineered Luminescent Oncolytic Vaccinia Virus Activation of Photodynamic‐Immune Combination Therapy for Colorectal Cancer

“…[ 32,33 ] Conversely, bioluminescence (BL) allows minimally invasive enzyme and substrate administration, exhibiting greater biocompatibility and overcoming visible light scattering and absorption issues. [ 34 ]…”

“…[32,33] Conversely, bioluminescence (BL) allows minimally invasive enzyme and substrate administration, exhibiting greater biocompatibility and overcoming visible light scattering and absorption issues. [34] In this study, a selectively replicable OVV expressing the firefly luciferase gene (Luc) was used as a vector to covalently couple with the PS Chlorin e6 (Ce6), forming OVV-Luc@Ce6 (OV@C); the coupling method has been described previously. [35] When combined with the substrate D-luciferin, OV@C acts as an internal light source, illuminating and activating the entire tumor.…”

Molecularly Engineered Near-Infrared Aggregation-Induced Emission Photosensitizer for In Situ-Activated Light Irradiation-Free Photodynamic Therapy

“…Due to the absorption and scattering effects in tissues, the effective light penetrating depth by a maximum permissible laser was restricted at millimeter ranges. − As an emerging solution, chemiexcited PDT offers a potential solution by harnessing the chemical energy from chemical reactions to excite PSs. In this approach, PSs can be directly excited to exhibit chemiluminescence (CL) and generate ROS, or they can undergo chemiluminescence resonance energy transfer (CRET) to achieve this effect . Luminol oxidation represents an effective method for implementing CL-PDT. − However, the emission of flash-type blue light and the potential biotoxicity associated with it have hindered the widespread application of luminol in designing CL-PDT platforms .…”