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Mild-Sunlight-Activated Safe Photodynamic Therapy Using On-Off Polymer Photosensitizers in Wearable Microneedle Patch
Yufu Tang1, Chunxu He2, Zhen Li3
1Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 1, Singapore, Singapore.
Nature Communications
|May 2, 2026
Summary
Mild sunlight-activated photodynamic therapy (PDT) uses microneedle patches for self-administered, deep-tissue treatment. This innovative approach minimizes side effects and eliminates prolonged light avoidance, offering a patient-friendly alternative.
Area of Science:
- Biomedical Engineering
- Photomedicine
- Materials Science
Background:
- Photodynamic therapy (PDT) shows promise but faces limitations including specialized equipment, clinic dependency, and phototoxicity requiring prolonged light avoidance.
- Current PDT methods necessitate fixed clinic visits and strict post-treatment light shielding, impacting patient compliance and quality of life.
Purpose of the Study:
- To develop a mild-sunlight-activated PDT (SunPDT) microneedle patch system for self-administered, deep-tissue treatment.
- To engineer photosensitizers with an "on-off" reactive oxygen species (ROS) generation mechanism for localized and bio-safe treatment.
- To eliminate the need for specialized light sources and prolonged post-treatment light avoidance.
Main Methods:
- Development of polymeric photosensitizers with an intrinsic "on-off" ROS generation mechanism.
- Integration of photosensitizers into microneedle patches for efficient, deep-tissue delivery.
- Utilizing low-intensity mild sunlight (12 mW/cm²) for photosensitizer excitation.
- Proof-of-concept study using female psoriatic mice.
Main Results:
- SunPDT microneedle patches demonstrated robust ROS generation under mild sunlight.
- The "on-off" ROS mechanism confined ROS generation to lesions, preventing off-target effects.
- Microneedle delivery enabled self-administration and treatment of deep-seated lesions.
- The SunPDT system achieved high therapeutic efficacy in a psoriatic mouse model, outperforming clinical Protoporphyrin IX patches.
- The triple-safety design eliminated the need for prolonged post-treatment light avoidance.
Conclusions:
- The "on-off" SunPDT microneedle patches offer a bio-safe, effective, and patient-friendly approach to PDT.
- This technology enables self-administered, deep-tissue treatment with minimal side effects and lifestyle integration.
- The developed platform represents a significant advancement for photodynamic therapy, moving towards at-home patient care.
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