19F- and 1H-NMR investigations of ofloxacin fluoroquinolone tethered with silver nanoparticles as synergistic antibiotic combinations

Abstract

The escalating demand for novel antibacterial agents has arisen due to the emergence of antibiotic-resistant strains among various pathogenic bacteria. This study investigates the molecular tethering of ofloxacin antibiotics and silver nanoparticles (AgNPs) to create a synergistic antibiotic compound known as ofloxacin−AgNPs. In solution, AgNPs form intramolecular bonds with the 9-fluorine atom and/or hydrogen in the 7-oxo-6-hydroxylic acid group of the ofloxacin molecule. Exploring the physicochemical and biomedical properties of ofloxacin−AgNPs, including viscosity, molecular dynamics, and molecular relaxations, is crucial for comprehending their efficacy as medical drugs. Furthermore, the ofloxacin−AgNPs system was subjected to 1H-NMR and 19F-NMR spectroscopic analyses, as well as an investigation of the spin-lattice relaxation time (T1). The T1 results indicate that the primary intramolecular bonding involves fluorine atoms, particularly those neighboring the proton and nitrogen atoms. Notably, the antimicrobial activity does not exhibit a linear correlation with the concentration of AgNPs, highlighting the substantial influence of physicochemical bonding on this activity.