Synthesis and characterization of linezolid conjugated silver nanoparticles using Thespesia Populnea leaf extract and evaluation of antibacterial efficacy against MDR pathogens: A novel method against MDR bacteria

Objective(s): Multidrug-resistant (MDR) organisms are posing threat by exhibiting resistance to commonly used antibiotics. From our study, we found a novel strategy to enhance the efficacy of antibiotics, which could help in treating diseases caused by various pathogens. We have used a natural, low-cost, biological reducing and capping agent, Thespesia populnea leaf extract to synthesize silver nanoparticles (AgNPs) and linezolid-conjugated silver nanoparticles (Li-AgNPs).Materials and Methods: The nanoparticles were characterized by UV-visible spectroscopy, Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FT-IR) spectroscopy. The antimicrobial activity was evaluated against MDR Staphylococcus aureus, Enterococcus faecalis, and Enterococcus faecium by agar well plate method. The UV-visible absorption spectra showed absorption peaks at 442 nm and 464 nm for AgNPs and Li-AgNPs, respectively. Results: The SEM analysis revealed particle size with a diameter ranging from 18 to 22 nm and 24 to 32 nm, respectively, and spherical in shape. The FT-IR spectrum has a distinct absorption band at 2065 cm-1 confirms adsorption of antibiotic linezolid on the AgNPs. The XRD pattern showed the characteristic absorption bands of 2 theta values, which confirms that NPs are crystalline in nature. The AgNPs and Li-AgNPs have exhibited the antibacterial potency. The Li-AgNPs have showed 25.8%, 7.6%, and 12.5% more microbial growth inhibition compared to antibiotic linezolid against E. faecalis, E. faecium,and S. aureus,respectively. Conclusion: All these results clearly indicated that the Li-AgNPs possesses enhanced antimicrobial activity than antibiotic linezolid, indicating the usefulness of this novel strategy to treat various communicable diseases caused by MDR pathogens.