Synthesis, Characterization, and Evaluation of Antimicrobial Efficacy of Sophorolipid-Coated Zinc Oxide Nanoparticles

In the present investigation, a study was conducted to evaluate the antimicrobial efficacy of sophorolipid-coated zinc oxide nanoparticles against certain pathogens. Sophorolipid is a glycolipid biosurfactant with reported antimicrobial properties. However, there is no report on the antimicrobial activity enhancement with sophorolipid-coated metallic nanoparticles. The study comprises of synthesis of sophorolipid-coated zinc oxide nanoparticles and characterization. The synthesized nanoparticles were characterized using various techniques such as FTIR, XRD, zeta potential determination, TGA, AFM, and FE-SEM coupled with EDX. Characterization of nanoparticles revealed that synthesized were found to be spherical crystalline nanoparticles with sizes ranging from 40 to 100 nm. They are stable under thermal treatment even at a temperature of 750 °C. Sophorolipid coating is found to decrease the accumulation of the nanoparticles as observed under AFM, indicating stabilization of the synthesized nanoparticles. The nanoparticles were also found to exhibit concentration-dependent antimicrobial activity against the pathogenic strains of Staphylococcus aureus, Escherichia coli, and Candida albicans.