Long-lived singlet oxygen surface disinfection technology

Overview

This technology addresses a key limitation of light-activated disinfection: the extremely short lifetime of singlet oxygen in aqueous solutions. By trapping singlet oxygen in a reversible reaction with 1,4-dimethylnaphthalene, the reactive species is converted into a long-lived endoperoxide that can persist and act as a disinfectant over practical timescales. The result is a solution-based disinfection method that works under standard indoor lighting conditions and provides a built-in visual indicator of completion through photobleaching.

The technology is particularly relevant for industries and institutions seeking effective, chemical-free surface disinfection methods that can be monitored visually and operated under ambient or low-intensity lighting.

Technical specifications

Core mechanism:

• Singlet oxygen is generated by irradiating Eosin Y, a visible-light-absorbing photosensitizer (525 nm), with low-intensity light
• Singlet oxygen is captured by 1,4-dimethylnaphthalene to form a metastable endoperoxide, extending its effective lifetime well beyond the microsecond range typical in water
• The endoperoxide can either act as an oxidant directly or release singlet oxygen on demand
• Triethanolamine serves as an electron donor, driving photobleaching of Eosin Y and generating superoxide as a secondary disinfecting species

Key features:

• Operates at 20 lumens per square foot, within the range of standard indoor lighting
• Photobleaching of Eosin Y produces a visible color change from yellow to colorless, signaling completion of the disinfection process
• Avoids surface staining through complete dye bleaching
• Validated through oxygen consumption monitoring using pressure sensors in sealed containers

Technology readiness level

The technology is currently at an early-to-mid stage of development. Proof-of-concept work has demonstrated the reversible trapping and release of singlet oxygen via the endoperoxide intermediate, as well as irreversible oxygen consumption through the Eosin Y/triethanolamine radical pathway. Ongoing validation efforts are focused on achieving complete surface disinfection and dye photobleaching within five minutes under 20 lumens per square foot illumination, using standardized use-dilution testing with bacterial colony counting and UV-Vis spectroscopy to confirm performance and non-staining behavior.