Novel optical measurement technique for antimicrobial photodynamic therapy using Scattered Light Integrating Collector (SLIC)

Advancing new treatment modalities for microbial infections is a priority, given the threat of antimicrobial resistance. Current work includes the development of new non-traditional treatments, including antimicrobial photodynamic therapy (aPDT). Improvements in the field include innovative technologies that allow screening and optimization of the treatment. In this work it is shown how the Scattered Light Integrating Collector, a novel technology that optically measures bacterial growth in real time, can be used for rapid screening of aPDT using Organic Light Emitting Diodes (OLEDs) as the light source. This technology allows rapid screening of different concentrations of the photosensitizer and real-time observation of the effect of aPDT on Staphylococcus aureus. Evaluation of aPDT efficacy using methylene blue and OLEDs as the light source showed significant inhibition of the growth of S. aureus (3.06, 3.80, 4.24, 4.98 and 4.84 log₁₀ reduction for the concentrations of MB of 1, 2, 4, 8 and 16 µM, respectively). The application of SLIC as a novel technology for evaluation of aPDT is a promising advance that will allow rapid optimization of the treatment.