الفهرس 
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Abstract
The thesis presents the investigation of the influence of femtosecond laser irradiation on the growth kinetics of the two most common infectious bacterial pathogens in wounds; Staphylococcus aureus and Pseudomonas aeruginosa, as an attempt to validate optimum parameters for a laser-based bactericidal modality to be used clinically. Bacterial cultures were exposed to femtosecond laser irradiation at different wavelengths, exposure times, and laser powers. The femtosecond laser source was INSPIRE HF100 laser system, Spectra-Physics, which is pumped by a mode-locked femtosecond Ti: sapphire laser MAI TAI HP, Spectra-Physics.
The survival of the bacterial cells was monitored after irradiation by: 1) Observing the clear zones of inhibition in cultured agar plates and 2) Determining growth rate kinetics using optical density. The second method is a rapid, simple, and reliable method for monitoring the bacterial growth rates. In addition, the growth rate of laser-exposed cultures was compared to control cultures. Results for all strains indicated that the exposure to femtosecond laser irradiation for fifteen minutes with a wavelength of 390 nm and 400 nm at an average power of 50 mW was enough to significantly reduce bacterial viability, with a lag in the growth phase of 5 hours longer than the control culture (P < 0.0001 by ANOVA and Tukey test).
Laser-based antibacterial photodynamic therapy could be a novel, non-invasive treatment option for localized infections. There are several clear-cut findings of this study that highlight the importance of optimizing laser exposure parameters such as wavelength, exposure time, average power, and energy density to achieve the best antibacterial effect.