Antimicrobial Photodynamic Therapy for Infectious Diseases

Antimicrobial photodynamic therapy (aPDT) harnesses the interaction of a non-toxic photosensitiser, visible light and molecular oxygen to generate cytotoxic reactive oxygen species (ROS) that inactivate bacteria, fungi and viruses. Upon illumination at a photosensitiser’s absorption wavelength, energy transfer to surrounding oxygen produces short-lived species such as singlet oxygen and free radicals. These oxidants inflict irreversible damage to microbial membranes, proteins and nucleic acids, effectively reducing pathogen viability without relying on conventional antibiotics. The multi-targeted mode of action minimises selection for resistant strains, making aPDT particularly attractive in the face of mounting antimicrobial resistance. Advances in formulation—ranging from small-molecule porphyrins to conjugates with antibiotics or peptides—have improved uptake, selectivity and ROS yield. Light delivery systems, including LEDs and optical fibres, enable treatment of superficial and deep-seated infections. Clinical translation has begun in wound care, oral decontamination and urinary tract infections, demonstrating safety and rapid microbial reduction. Key challenges include optimisation of photosensitiser localisation, penetration in biofilms and minimisation of host tissue phototoxicity. Ongoing research seeks to integrate nanotechnology, targeted conjugates and adjuvants such as halide salts to potentiate aPDT efficacy. The global significance of aPDT lies in its potential to supplement or replace antibiotics, preserve microbiome balance and address infections in resource-limited settings by using low-cost light sources and broadly active photosensitisers.

Research from Nature Portfolio

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Antimicrobial Photodynamic Therapy for Infectious Diseases publication trend

The graph below shows the total number of articles in antimicrobial photodynamic therapy for infectious diseases across all publications each year (not limited to Nature Index journals).

Technical terms

Photosensitiser: A molecule that absorbs light and transfers energy to oxygen, producing reactive oxygen species.

Reactive oxygen species (ROS): Highly reactive chemical species, including singlet oxygen and free radicals, that damage microbial biomolecules.

Singlet oxygen: An electronically excited form of oxygen with high reactivity towards biological targets.

Biofilm: A structured community of microorganisms embedded in a self-produced polymeric matrix, often resistant to antibiotics.

Phototoxicity: Damage caused to cells or tissues by light-activated compounds producing ROS.

References

1. Alkylated EDTA potentiates antibacterial photodynamic activity of protoporphyrin. Journal of Nanobiotechnology (2024).
2. Starch-based films doped with porphyrinoid photosensitizers for active skin wound healing. Carbohydrate Polymers (2023).
3. Riboflavin-Vancomycin Conjugate Enables Simultaneous Antibiotic Photo-Release and Photodynamic Killing against Resistant Gram-Positive Pathogens. JACS Au (2023).