Synergistic Nanocomposites of Different Antibiotics Coupled with Green Synthesized Chitosan-Based Silver Nanoparticles: Characterization, Antibacterial, in vivo Toxicological and Biodistribution Studies

The present study reports chitosan functionalized green synthesized CS-AgNPs, conjugated with amoxicillin (AMX), cefixime (CEF), and levofloxacin (LVX) for safe and enhanced antibacterial activity. The CS-AgNPs and conjugates CS-AgNPs+AMX CS-AgNPs+CEF, and CS-AgNPs+LVX were characterized by UV-Vis, FTIR, SEM, TEM, EDX spectroscopy. The size distribution and zeta potential were measured using the dynamic light scattering (DLS) technique. The interaction between CS-AgNPs and antibiotic molecules was also investigated using UV-Vis spectroscopy at the concentrations of 5, 50, 500, and 5000 µM for each antibiotic. Antibacterial activity and synergism were assessed by the Fractional Inhibitory Concentration (FIC) index. The mechanism for synergistic activity was investigated by the detection of hydroxyl species based on the chemiluminescence of luminol. The biocompatibility index (BI) was calculated from IC using the HeLa cell line. In vivo toxicity and tissue distribution of silver ions were evaluated on Sprague Dawley rats. Physical interactions of antibiotics and significant (P