Exploring the role of impedance spectroscopy in assessing 405 nm laser-induced inactivation of saccharomyces cerevisiae.

ABSTRACT

Impedance spectroscopy was employed to assess the electrical properties of yeast following 405 nm laser irradiation, exploring the effects of visible, non-ionizing laser-induced inactivation as a more selective and safer alternative for photoinactivation applications compared to the use of DNA targeting, ionizing UV light. Capacitance and impedance spectra were obtained for yeast suspensions irradiated for 10, 20, 30, and 40 min using 100 and 200 mW laser powers. Noticeable differences in capacitance spectra were observed at lower frequencies (40 Hz to 1 kHz), with a significant increase at 40 min for both laser powers. ß-dispersion was evident in the impedance spectra in the frequency range of 10 kHz to 10 MHz. The characteristic frequency of dielectric relaxation steadily shifted to higher frequencies with increasing irradiation time, with a drastic change observed at 40 min for both laser powers. These changes signify a distinct alteration in the physical state of yeast. A yeast spot assay demonstrated a decrease in cell viability with increasing laser irradiation dose. The results indicate a correlation between changes in electrical properties, cell viability, and the efficacy of 405 nm laser-induced inactivation. Impedance spectroscopy is shown to be an efficient, non-destructive, label-free method for monitoring changes in cell viability in photobiological effect studies. The development of impedance spectroscopy-based real-time studies in photoinactivation holds promise for advancing our understanding of light-cell interactions in medical applications.