Evaluation of riboflavin concentrations and light intensities on bacteria reduction in platelets using visible light

Bacterial contamination in platelets has been a major concern over the years. In this study, we showed that treatment with 420 nm visible light with various concentrations of riboflavin in platelets reduced E. coli and S. aureus by 0–1.56 and 0.3–2.02 logs (50 mW/cm²), 2.24–4.77 and 0.73–3.26 logs (75 mW/cm²), and ≥ 5.14 and ≥ 5.27 logs (100 mW/cm²). Treatment with high-intensity light (100 mW/cm²) and high concentrations of riboflavin (400 µM and 500 µM) effectively reduced both bacteria in platelets by over 4 logs. The study also found a positive correlation between bacterial reduction and light intensity, as well as riboflavin concentration in a dose-dependent manner. These results demonstrate the potential of using riboflavin and visible light to reduce the risk of bacterial contamination in platelets, and support the need for further exploration of pathogen reduction using 420 nm visible light and riboflavin.