Potential Application of Silver Nanoparticles Synthesized Using Cassia abbreviata Aqueous Extracts in Water Treatment

Abstract

Nanotechnology is being recognized for its potential in addressing global drinking water issues, managing microbial risks, and meeting stringent water quality standards. However, there is a lack of information on the efficacy of silver nanoparticles synthesized using indigenous African herbal plants in eradicating harmful bacteria in contaminated water. This study introduces, for the first time, the use of the herbal plant Cassia abbreviata for the biosynthesis of silver nanoparticles. The biosynthesized silver nanoparticles were characterized using UV-vis spectrophotometer and atomic force microscope (AFM) techniques. The silver nanoparticles exhibited absorption peaks in the 400 to 500 nm range, with an average size ranging from 18 to 33 nm and a rough surface topography. These silver nanoparticles demonstrated potent antibacterial effects against both Gram-positive and Gram-negative pathogenic bacteria, regardless of whether the aqueous extract of leaves, stem barks, or root barks of C. abbreviata was utilized. The minimum inhibitory concentration (MIC) values for Gram-positive and Gram-negative bacteria ranged from <0.03 to 1.69 mg/mL. Additionally, the silver nanoparticles efficiently reduced high levels of fecal coliform bacteria (>10⁵ cfu/100 mL) in surface water to undetectable levels within 4 hours at a concentration of >9.37 mg/mL, showcasing their potential for water purification. Findings from this study demonstrate that aqueous extracts of C. abbreviata leaves, stem barks and root barks are excellent precursors for producing silver nanoparticles with robust antimicrobial and disinfectant properties.