In vitro antimicrobial photodynamic therapy for methicillin-resistant Staphylococcus aureus using flexible organic light-emitting diode

The most critical aspect of managing methicillin-resistant S. aureus (MRSA) infections is preventing their spread by directly controlling MRSA. Studies have revealed that light-emitting diodes (LEDs) or lasers can be used for photodynamic therapy (PDT) to effectively kill MRSA. Organic light-emitting diodes (OLEDs) can also be used as a light source for PDT, but research cases are extremely rare, and most of them have used low-power OLEDs. Therefore, verification studies using high-power OLEDs are required to increase the utilization of OLEDs in PDT applications. In this study, we examined the inactivation effects of PDT on MRSA using a low-voltage/ high-power OLED device. The 632 nm OLED emitted 5-40 mW/cm² of light at less than 5 V, and 22 mW/cm² of light was selected as the optimal condition for OLED-PDT. The inactivation effects of OLED-PDT with 10 μM methylene blue (MB) against MRSA suspension (39.6 J/cm²), MRSA biofilm (79.2 J/cm²), and MRSA-inoculated porcine skin (39.6 J/cm²) were approximately 86.2%, 73.4%, and 80.2%, respectively. In conclusion, the combination of low-voltage/ high-power OLED and MB could be a promising way to reduce the risk of bacterial infection, contributing to the development of effective portable or wearable medical devices.