Comparative Study on Antibacterial Activity of Metal Ions, Monometallic and Alloy Noble Metal Nanoparticles Against Nosocomial Pathogens

Abstract

Unbeatable widespread antimicrobial resistance in nosocomial pathogens is a major public health concern in hospitals. In the present study, aqueous stem extract of C. tagal (CTSE) is used as a bioreducing agent for synthesis of various monometallic and alloy nanoparticles. Nanoparticle formation was dependent on time, temperature, and metal salts’ concentration. UV-Visible spectroscopy demonstrated peaks at 444 and 556 nm for silver and gold nanoparticles, respectively, while both alloy Ag–Au nanoparticles exhibited peaks at 535 nm. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy results revealed shape, size, and involvement of functional groups in formation of stable nanoparticles. Further, minimum inhibitory concentration (MIC) of two metal ions, four monometallic nanoparticles, and two alloy noble metal nanoparticles was evaluated against nosocomial pathogens. Silver nanoparticles synthesized from AgNO3 and Ag2SO4 exhibited cytotoxicity against all tested microorganisms. Alloy (Ag–Au) nanoparticles from salts of silver nitrate and gold were more effective than alloy nanoparticles prepared from salts of silver sulfate and gold. However, gold and copper nanoparticles were effective only against Staphylococcus aureus and Escherichia coli respectively. Ionic silver was more cytotoxic as compared to copper ions and monometallic and alloy nanoparticles. This is the first report on comparative antimicrobial activity of metal ions and various nanoparticles synthesized from CTSE against nosocomial pathogens from the intensive care unit (ICU) and burn wound intensive care unit (BWICU).