Characterization and Antimicrobial Assessment of Cadmium Sulfide Nanoparticles

Resistance to conventional antibiotics remains a global health challenge. The search for more effective antimicrobial agents has led to the consideration of nanoparticles due to their potential biocidal activities. This study synthesized, characterized, and evaluated the antimicrobial behavior of cadmium sulfide nanoparticles (CdS NPs) during incubations at 37 °C and at room temperature (rt; 23 to 27 °C). XRD results showed that the synthesized nanoparticles had a cubic zinc blende structure, while microscopic investigations confirmed the particle size to be 7.236 nm on average. UV-Vis spectroscopy showed that the nanoparticles are active in the visible light region. Raman spectroscopy results showed peaks at 302.3 cm^-1 and 601 cm^-1, which represent the first- and second-order longitudinal optical phonon. Agar well diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) assays were conducted to investigate the antimicrobial activity of CdS NPs (50 mg/mL, 25 mg/mL, and 10 mg/mL) against <i>Escherichia coli</i> and <i>Staphylococcus aureus</i>. CdS NPs were effective against both test organisms. However, they were more effective against Gram-negative <i>E. coli</i>. The higher the concentration of CdS NPs, the more effective they were against the test organisms. Furthermore, MBC results showed greater bactericidal activity of CdS NPs at 37 °C. With increasing incidences of antimicrobial resistance against conventional antimicrobial agents, especially in wastewater treatment, nanoparticles are considered promising alternatives and the next generation of antimicrobial agents.