Chaenomeles japonica Mediated Fabrication of Silver Nanoparticles and Their Conjugates with Ceftriaxone: Characterization and Antibacterial Effect

Biosynthesized metal nanoparticles have unique properties and are being actively studied as potential antimicrobial agents against resistant pathogens. The “green” synthesis of silver nanoparticles and their conjugate with the antibiotic ceftriaxone, carried out using the aqueous extract of Chaenomeles japonica leaves as a biological matrix, is reported here for the first time. UV-visible spectra confirmed the creation of biosynthesized silver nanoparticles (Ch-AgNPs) and their conjugates with ceftriaxone (Ch-AgNPs-Cfx), which were characterized by surface plasmon resonance absorption peaks at 475 and 478 nm, respectively. Fourier transform infrared spectrum analysis revealed the participation of hydroxyl and carboxyl functional groups of phenolic and aromatic compounds, flavonoids, terpenoids, alcohols, and carboxylic acids of the plant extract in the process of bioreduction of Ag+ to Ag0 as well as the involvement of carbonyl and amine groups of proteins in blocking and stabilization silver nanoparticles. The antimicrobial activity of Ch-AgNPs, Ch-AgNPs-Cfx, and ceftriaxone was evaluated using a disk diffusion assay against Pseudomonas aeruginosa strain resistant to some cephalosporins. Studies have shown a dose-dependent inhibition of P. aeruginosa by Ch-AgNPs and Ch-AgNPs-Cfx in the range of 2.5–20 μg/disk, which exceeded the activity of ceftriaxone at the same doses, which characterizes both types of biosynthesized nanoparticles as promising bactericidal agents. Further research on Ch-AgNPs and Ch-AgNPs-Cfx may be aimed at creating effective means to reduce the antibiotic doses without losing antibacterial activity against resistant pathogens.