Effect of photodynamic therapy potentiated by ultrasonic chamber on decontamination of acrylic and titanium surfaces.

Photodynamic Therapy (PDT) is an alternative to surface decontamination that is based on the interaction between a non-toxic photosensitizer (PS) and a light source to allow for the formation of reactive oxygen species. The objective of this study was to test a new patented device - the "Ultrasonic Photodynamic Inactivation Device" (UPID) under the patent deposit MU-BR 20.2018.00.9356-3 - for the photodynamic inactivation on contaminated acrylic plates and titanium disk. This new low cost device contains light emitting diodes (LEDs) and was built in a stainless-steel container for better light distribution. In addition, 28 waterproof red LEDs plates, with a wavelength of 660 nm were used, containing three irradiators in each plate, for which the irradiation distribution and the spectral irradiance on all 6 internal faces of this device were calculated. The effect of red LED irradiation (660 nm) methylene blue (MB) (100 µmol/L) diluted in water or 70% alcohol on three types of microorganisms: Candida albicans ATCC 10231, Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922. In order to estimate the effects of PDI, acrylic plates and Titanium disks were contaminated by bacterial suspensions (3 × 108 CFU/mL), then treated with a solution of MB for 30 min, followed by irradiation for 30 min (0.45 J/cm2). Microbial inhibition was evaluated by counting the number of colony forming units (CFU), compared to the control group. The results showed that the UPID promoted significant reduction (p < 0.001) of the microorganism when compared with the positive control. The new device promoted an effective microbial inhibition on the surfaces tested and, thus, makes possible new studies. The perspective is that this new device may be a low-cost and non-toxic alternative to the disinfection of biomedical devices, non-critical instruments and also for use in the food industry.