Singlet Oxygen Dynamics in Photophysical and Photodynamic Systems

Singlet oxygen is an electronically excited form of molecular oxygen generated when a photosensitiser in its excited triplet state transfers energy to ground-state oxygen. Its lifetime, diffusion distance and reactivity depend on the local environment, including solvent, molecular quenchers and confining media. In photophysical systems, precise control of excited-state kinetics and probe design underpins quantitative measurement and elucidation of energy-transfer pathways. In photodynamic applications, efficient singlet oxygen production is central to non-invasive therapies, with challenges arising from limited light penetration, tumour hypoxia and off-target oxidation. Advances in nanomaterials, genetically encoded proteins and multifunctional carriers are integrating photophysical insights with biological specificity, enabling enhanced control over singlet oxygen delivery for imaging, materials processing and clinical interventions.

Research from Nature Portfolio

Recent structural studies of a flavin-binding photosensitiser have revealed the molecular origins of high singlet oxygen yield. High-resolution crystallography identified competing oxygen- and protein-quenching pathways, a light-induced flavin transformation that enhances oxygen access to the chromophore, and progressive oxidation of surface residues, collectively elevating quantum yield by an order of magnitude. In parallel, multifunctional gene-delivery platforms exploit tumour acidity to trigger charge reversal and promote cellular uptake of p53-encoding genes alongside a photosensitising protein. Upon light activation, this system achieves robust singlet oxygen generation in vivo, substantially suppressing tumour growth and extending survival in preclinical models.

Singlet Oxygen Dynamics in Photophysical and Photodynamic Systems publication trend

The graph below shows the total number of articles in singlet oxygen dynamics in photophysical and photodynamic systems across all publications each year (not limited to Nature Index journals).

Technical terms

Singlet oxygen: An electronically excited form of molecular oxygen with paired electrons, highly reactive in oxidation reactions.

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

Triplet state: A molecular excited state with two unpaired electrons and slower decay kinetics than the singlet state.

Quantum yield: The ratio of the number of singlet oxygen molecules generated to the number of photons absorbed.

Photodynamic therapy (PDT): A clinical modality using light-activated photosensitisers to induce cytotoxic singlet oxygen in target tissues.

Upconversion nanoparticles: Nanomaterials that absorb low-energy photons and emit higher-energy light, enabling deep-tissue activation.

References

1. Photosensitizing deep-seated cancer cells with photoprotein-conjugated upconversion nanoparticles. Journal of Nanobiotechnology (2023).
2. The detection sensitivity of commonly used singlet oxygen probes in aqueous environments. Journal of Photochemistry and Photobiology B Biology (2020).
3. Tailoring photosensitive ROS for advanced photodynamic therapy. Experimental & Molecular Medicine (2021).
4. Highly specific in vivo gene delivery for p53-mediated apoptosis and genetic photodynamic therapies of tumour. Nature Communications (2015).
5. Tailing miniSOG: structural bases of the complex photophysics of a flavin-binding singlet oxygen photosensitizing protein. Scientific Reports (2019).