2022-07-01 16:26


Conference: Bucharest University Faculty of Physics 2019 Meeting

Section: Optics, Spectroscopy, Plasma and Lasers

Characterization and identification of antimicrobial species generated from thioridazine irradiated with 266 nm laser beam

Tatiana TOZAR (1), Mihai BONI (1), Ana-Maria UDREA (1), Angela STAICU (1), Mihail L. PASCU (1,2)

1) National Institute for Laser, Plasma and Radiation Physics, Magurele, Romania

2) Faculty of Physics, University of Bucharest, Magurele, Romania


Thioridazine, Laser induced fluorescence, Fluorescence lifetime, HPTLC

One of the most important health-related problems is the fight against multiple drug-resistant bacterial pathogens and large efforts in drug development are directed towards fast and efficient ways to combat it. In this respect, UV laser exposed thioridazine solutions proved to be suitable candidates in fighting antimicrobial resistance in gram-positive bacteria. The antimicrobial activity of the irradiated medicine solutions was improved several times and the toxicity decreased when compared with the unirradiated solutions. Typically, an investigated solution was aqueous thioridazine solution exposed to 266 nm laser radiation for various irradiation intervals, ranging from 1 minute to 240 minutes. The susceptibility assays performed on gram-positive bacteria was used to select the irradiated thioridazine solutions that possessed the best antimicrobial activity. The techniques used to identify/measure the obtained photoproducts were absorption spectroscopy, Thin Layer Chromatography (TLC), Laser Induced Fluorescence (LIF), FTIR, and, surface tensions measurements. After the separation of the photoproducts on HPTLC plates, the photoproducts were characterized by steady-state and time-resolved fluorescence spectroscopy. The HPTLC plates were investigated using a single-track scanner that employed a monochromatic light generated by picosecond laser, where an optical fiber was used to collect reflected light in conjunction with a spectrograph (fluorescence) and oscilloscope (fluorescence lifetime). In conclusion, these techniques proved to be suitable analytical means to study the photoproducts formed during irradiation and provided information about the transformations that occur in the molecular structure during irradiation.

This work was supported by the Romanian National Authority for Scientific Research and Innovation, CNCS/CCCDI-UEFISCDI, projects number PN-III-P1-1.1-PD-2016-1072 and PN-III-P1-1.1-PCCDI-2017-0728 and NUCLEU Program 16N/08.02.2019.