Comparison of pulse and super pulse radiation modes' singlet oxygen production effect in antimicrobial photodynamic therapy (AmPDT)

Photodynamic Therapy (PDT) is a treatment method in which a target region is irradiated with a light source of an appropriate wavelength to activate an introduced photosensitizer to ideally ablate the target by creation of highly toxic singlet oxygen. Due to the increment of antibiotic resistant bacteria, PDT has also become a salient method for infection treatments. The amount and the location of singlet oxygen gives information about the effectiveness of PDT. The quantitative evolution of singlet oxygen is a gold standard for the real time monitoring of the treatment efficiency during PDT. In the proposed study, the effect of radiation modes on PDT is investigated with singlet oxygen explicit dosimetry (SOED) and singlet oxygen luminescence dosimetry (SOLD) methods. For this purpose, super pulse and pulse radiation modes are applied for antimicrobial PDT (AmPDT). Five in vitro experiments were carried out to investigate the effect of radiation mode. According to the achieved results, super pulse mode provides 3-10 % more singlet oxygen concentration and 2-5 % more bacteria (Staphylococcus Aureus) death (necrosis and apoptosis) than pulse mode. Furthermore, radiation mode effect on instantaneous and cumulative singlet oxygen concentration is considered in the experiments. It is demonstrated that the singlet oxygen concertation measured by SOED and SOLD methods are coherent. Thus, the SOED method can be used for real-time singlet oxygen measurements during PDT.