Flexible organic light-emitting diodes for antimicrobial photodynamic therapy

Bacterial infection and the growth of antibiotic resistance is a serious problem that leads to patient suffering, death and increased costs of healthcare. To address this problem, we propose using flexible organic light-emitting diodes (OLEDs) as light sources for photodynamic therapy (PDT) to kill bacteria. PDT involves the use of light and a photosensitizer to generate reactive oxygen species that kill neighbouring cells. We have developed flexible top-emitting OLEDs with the ability to tune the emission peak from 669 to 737 nm to match the photosensitizer, together with high irradiance, low driving voltage, long operational lifetime and adequate shelf-life. These features enable OLEDs to be the ideal candidate for ambulatory PDT light sources. A detailed study of OLED–PDT for killing Staphylococcus aureus was performed. The results show that our OLEDs in combination with the photosensitizer methylene blue, can kill more than 99% of bacteria. This indicates a huge potential for using OLEDs to treat bacterial infections. Flexible OLED technology is becoming increasingly mature and is ready to open new directions in antimicrobial photodynamic therapy. An international team led by Prof Ifor Samuel from University of St Andrews, UK presents a comprehensive study to show that flexible organic light-emitting diodes (OLEDs) are ideal light sources to be used in photodynamic therapy to kill bacteria. They design the OLED device structure to enable large area, high uniformity, low driving voltage, long operational lifetime, adequate shelf-life and colour tunability and address all the requirements of photodynamic therapy. Actual biological experiments show killing rates of more than 99% for S. aureus bacteria. The approach clearly demonstrates the huge potential of OLEDs for treatment of bacterial infections and future wearable healthcare devices.