Photolysis of Bovine Serum Albumin by near UV irradiation

Proteins are major biological targets for oxidative damage due to their abundance and high rates of reactions with reactive oxygen species including radicals and excited state species. This work studies the photooxidation of Bovine Serum Albumin (BSA) by singlet molecular oxygen (1O2) using Raman spectroscopy which allows the spectral changes induced by oxidation to be directly identified. The results show that these changes mainly affect the S-S and the amide Raman bands. Tri-peptides containing amino acids His, Met, Trp and Tyr whose side chains are known to preferentially react with 1O2 are also analysed allowing the specific changes associated with each amino acid to be observed and discussed within the context of the changes observed in the protein. The singlet oxygen quenching rate constants for BSA were measured using time resolved near infrared phosphorescence. It was found that the rate constants vary as a function of pD thus highlighting the effect of conformation on the process of oxidation

TiO2 nanoparticles influence on rhodamine 6G droplet emission

This work aims to investigate the effect of TiO 2 nanoparticles addition on the fluorescence emission of solutions of Rhodamine 6G excited in micro-volumetric droplets. In this paper are presented the similarities and the differences of the emission spectra by modifying parameters such as TiO 2 concentration, solutions pH and laser fluence. The pumping laser source used was the second harmonic beam emitted by a pulsed ns Nd:YAG laser at 532 nm. Lasing emission is observed and it is favorised by the solution acidity and laser beam intensity. © 2018, Editura Academiei Romane. All rights reserved

TiO2 nanoparticles influence on rhodamine 6G droplet emission

This work aims to investigate the effect of TiO 2 nanoparticles addition on the fluorescence emission of solutions of Rhodamine 6G excited in micro-volumetric droplets. In this paper are presented the similarities and the differences of the emission spectra by modifying parameters such as TiO 2 concentration, solutions pH and laser fluence. The pumping laser source used was the second harmonic beam emitted by a pulsed ns Nd:YAG laser at 532 nm. Lasing emission is observed and it is favorised by the solution acidity and laser beam intensity. © 2018, Editura Academiei Romane. All rights reserved

SARS-CoV-2 Breakthrough Infections: Incidence and Risk Factors in a Large European Multicentric Cohort of Health Workers

The research aimed to investigate the incidence of SARS-CoV-2 breakthrough infections and their determinants in a large European cohort of more than 60,000 health workers

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts. June 4-7, 2019, Szczyrk, Polan

Optical Characterization of Ciprofloxacin Photolytic Degradation by UV-Pulsed Laser Radiation

Ciprofloxacin is one of the most prescribed antibiotics in treating bacterial infections, becoming an important pollutant of the wastewaters. Moreover, ciprofloxacin is hard to be destroyed by conventional water treatment processes; therefore, efficient treatments to destroy it are needed in water decontamination. This study offers insights into the performance of 266 nm laser beams on the photodegradation of ciprofloxacin. An Nd:YAG laser was used that emitted 266 nm at an energy of 6.5 mJ (power of 65 mW) and ciprofloxacin water solutions were irradiated up to 240 min. The irradiated solutions were investigated by UV-Vis and FTIR absorption spectroscopy, pH assay, and laser-induced fluorescence. An HPTLC densitometer was used to characterize the laser-induced fluorescence and fluorescence lifetime of photodegradation products. The UV-Vis absorption, FTIR, and laser-induced fluorescence spectra showed the degradation of ciprofloxacin. Moreover, HPTLC densitometry offered the fluorescence and fluorescence lifetime of ciprofloxacin and its three photoproducts as well as their relative quantification. From the FTIR spectra, the molecular structure of two out of three photoproducts was proposed. In conclusion, the laser irradiation method provided the efficient photodegradation of ciprofloxacin, whereas the analytical techniques offered the proper means to monitor the process and detect the obtained photoproducts

Target Prediction of 5,10,15,20-Tetrakis(4′-Sulfonatophenyl)-Porphyrin Using Molecular Docking

Photodynamic therapy has the potential to be a new and effective cancer treatment. Even if in vitro and in vivo research show promise, the molecular mechanism remains unclear. In this study, molecular docking simulations predict the binding affinity of the 5,10,15,20-tetrakis(4′-sulfonatophenyl)-porphyrin tetraammonium photosensitizer on several potential targets in photodynamic treatment. Our results indicate that this photosensitizer binds to several receptor targets, including B-cell lymphoma 2 (BCL-2) and other related proteins BCL-xL, MCL-1, or A1. The binding affinity of the porphyrin derivative with human serum albumin was determined using UV–vis absorption spectroscopy and predicted using molecular docking. We conclude that the studied porphyrin photosensitizer binds to human serum albumin and may inhibit the cancer cell line through its interactions with HIS and MET AA residues from BCL-2, MCL-1, and β-catenin receptors or through its low estimated free energy of binding when interacting with A1 and BCL-B receptors

Photophysical study of Zn phthalocyanine in binary solvent mixtures

International audiencePhotophysical properties of phthalocyanines are important in photodynamic therapy, where these compounds are proposed as photosensitizing agents. We report here some significant solvent effects on the photophysical properties of Zn phthalocyanine (ZnPc) observed in binary solvent mixture dimethyl sulfoxide/water at several ratios of cosolvents. The absorbance of ZnPc at the maximum of Q band has a sharp drop in intensity for a water mass percent in the solvent mixture larger than 40%. The same characteristic shows also the quantum yield of fluorescence. A particular result is the increase of singlet oxygen lifetime for water percentage raise up to 20% in the solvent mixture. The effects are discussed in connection with the particular solvent microenvironment, involving DMSO/water clusters formation and the strong interaction between the solute and the solvent