Opinion Article - Journal of Dermatology Research and Skin Care (2025) Volume 9, Issue 3

How Photodynamic Therapy Works: Light, Oxygen, and Cellular Destruction

Zhen Ran^*

Department of Pharmacy &International Academy, Chongqing University, China

*Corresponding Author:

Zhen Ran
Department of Pharmacy &International Academy, Chongqing University, China
E-mail: zhenr@cqwu.edu.cn

Received: 03-Sep -2025, Manuscript No. AADRSC-25-167964; Editor assigned: 04-Sep-2025, PreQC No. AADRSC-25-167964 (PQ); Reviewed:17-Sep-2025, QC No. AADRSC-25-167964; Revised:22-Sep-2025, Manuscript No. AADRSC-25-167964(R); Published:27-Sep-2025, DOI:10.35841/aadrsc-9.3.272

Citation: Ran Z. How photodynamic therapy works: Light, oxygen, and cellular destruction. Dermatol Res Skin Care. 2025; 9(3):272

Introduction

Photodynamic therapy (PDT) is a minimally invasive medical treatment that harnesses the power of light, photosensitizing agents, and oxygen to selectively destroy diseased cells. Widely used in dermatology, oncology, and ophthalmology, PDT is gaining recognition for its effectiveness and targeted mechanism of action. The core process involves activating a photosensitizing compound in the presence of light, producing reactive oxygen species (ROS) that damage cellular components and lead to cell death. This article explores the science behind photodynamic therapy, its applications, advantages, and challenges.[1].

This is a light-sensitive compound that accumulates in abnormal or diseased tissues. Common photosensitizers include 5-aminolevulinic acid (ALA), methyl aminolevulinate (MAL), and porfimer sodium. Specific wavelengths of light (usually in the red or blue spectrum) activate the photosensitizer. The choice of wavelength depends on the absorption spectrum of the PS and the depth of the target tissue. When the activated photosensitizer transfers energy to molecular oxygen, it generates reactive oxygen species (ROS), such as singlet oxygen and free radicals. These ROS are toxic to cells and initiate cellular destruction. The photosensitizer can be applied topically (for skin conditions), injected intravenously (for internal cancers), or taken orally, depending on the condition being treated.[2].

The compound preferentially accumulates in diseased cells due to differences in metabolism, vascularity, or cell membrane permeability. Healthy tissues generally clear the photosensitizer more rapidly. After an incubation period, the affected area is exposed to a specific wavelength of light. This excites the photosensitizer to a higher energy state. The excited photosensitizer interacts with molecular oxygen, producing ROS that cause oxidative damage to cellular structures, including mitochondria, lysosomes, and DNA. The cumulative oxidative damage triggers apoptosis (programmed cell death), necrosis, or autophagy, effectively killing the targeted cells without significant harm to surrounding healthy tissue.[3].

PDT is commonly used for treating actinic keratoses, basal cell carcinoma, acne, and photoaging. ALA or MAL is applied topically, followed by exposure to red or blue light. In certain cancers (e.g., esophageal, lung, bladder), PDT is used to shrink tumors, relieve symptoms, or destroy residual cancer cells after surgery. Porfimer sodium is typically the photosensitizer used PDT has shown promise in treating bacterial, viral, and fungal infections, especially drug-resistant strains, due to its non-specific mechanism of oxidative damage. Patients may experience heightened sensitivity to light for up to 48 hours post-treatment due to residual photosensitizers.[4].

Side effects are typically mild but may include redness, swelling, and discomfort at the treatment site. In rare cases, scarring or pigment changes can occur. Research is ongoing to develop next-generation photosensitizers with deeper tissue penetration, greater selectivity, and faster clearance from healthy tissues. Nanotechnology and targeted delivery systems are also being explored to improve photosensitizer uptake by cancer cells [8]. Combining PDT with other therapies—like immunotherapy or chemotherapy—may further enhance treatment outcomes [5].

Conclusion

Photodynamic therapy offers a powerful, targeted approach to destroying abnormal or diseased cells using light, oxygen, and photosensitizers. Its versatility across medical fields from dermatology to oncology underscores its growing importance in modern medicine. While some challenges remain, ongoing research continues to expand its potential and refine its application. As science advances, PDT may become even more integral to non-invasive, precise treatment strategies for various medical conditions.

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