DNA influence on norfloxacin fluorescence

Abstract

The emission properties of norfloxacin, a quinolone antibiotic, in presence of salmon sperm DNA were studied at room temperature and in conditions of acid, alkaline and neutral pH. It was found that norfloxacin molecules are inserted between the DNA base pairs, as evidenced by the emission spectra features and the significant increases in relative viscosity of DNA by the addition of norfloxacin. The fluorescence quenching process was characterized by Stern-Volmer plots which display a positive deviation from the linearity. The analysis was performed in terms of the Stern-Volmer modified equations including both dynamic and static quenching. The use of the finite sink approximation model showed that the process of quenching of the norfloxacin fluorescence with DNA was diffusion limited, irrespective to the pH of the work solution. At the same time, relying on the formation of the ground state complex model and the sphere of action static quenching model, we concluded that the quenching reaction from the norfloxacin - DNA system is due to the combined effect of both dynamic and static quenching processes.

Keywords: DNA; Finite sink approximation; Fluorescence quenching; Ground-state complex; Norfloxacin; Sphere of action static quenching; Stern–Volmer plots.