Synthesis of Schiff Base Encapsulated ZnS Nanoparticles: Characterization and Antibacterial Screening

In this study, Schiff bases containing salicylaldehyde moiety (namely salicylaldehyde 2-methyl-3-thiosemicarbazone and salicylaldehyde triazole) were synthesized using the conventional refluxing method. The Schiff bases were utilized in the encapsulation of ZnS nanoparticles using the co-precipitation method. The nanoparticles were characterized using FTIR, UV-visible absorption spectroscopy, scanning electron microscopy, and energy dispersive X-ray analysis. X-ray diffraction analyses suggest that the Schiff base encapsulated ZnS particles form the cubic crystal phase of ZnS, with the average crystallite sizes being approximately between 56 and 60 nm. The interaction between the Schiff bases and ZnS was also evaluated by photoluminescence spectroscopy. The antibacterial activities of the Schiff base encapsulated ZnS nanoparticles were screened against four different gram-positive and gram-negative bacterial strains (i.e. Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, and Staphylococcus aureus) using the agar diffusion method. The antibacterial activities of the nanoparticles were compared with those of their respective Schiff bases. Although in the current study the Schiff base encapsulated ZnS nanoparticles were found to be inactive against those bacteria, they could be applicable as multifunctional materials for fluorescence probes, photocatalysts, and other biological applications.