Green synthesis of silver nanoparticles using Phyllanthus emblica extract: investigation of antibacterial activity and biocompatibility in vivo†

Abstract

The application of nanotherapeutics is being considered as one of the most sought-after strategies to combat the threat posed by drug resistant bacteria. One promising type of nanotherapeutic is biogenic silver nanoparticles (bAgNPs) generated through exploiting the reducing potential of plant extracts. Herein, bAgNPs were synthesized at pH 7.4 (bAgNPs) and pH 10 (bAgNPs@pH) through green chemistry approaches using an extract of Phyllanthus emblica fruit as a source of reducing agent. The physicochemical properties, antibacterial potential, and biocompatibility of the as-synthesized bAgNPs were determined. The average size of bAgNPs and bAgNPs@pH was 15.3 and 20.1 nm, respectively, and both types of nanoparticles were negatively charged (i.e., ∼−25 mV). The as-synthesized bAgNPs exhibited excellent antibacterial activity against different bacterial strains such as Bacillus subtilis RBW, Escherichia coli DH5a, Salmonella typhi, Hafnia alvei, enteropathogenic E. coli, Vibrio cholerae, and Staphylococcus aureus. The most effective antibacterial activity of bAgNPs and bAgNPs@pH was observed against Hafnia alvei, a Gram-negative bacterium, with a zone of inhibition (ZOI) of ∼24 and 26 mm in diameter, respectively. The nanoparticles exhibited antibacterial activity through damaging the bacterial cell wall, oxidizing the membrane fatty acids, and interacting with cellular macromolecules to bring about bacterial death. Furthermore, bAgNPs showed excellent hemocompatibility against human red blood cells, and there was no significant toxicity observed in rat serum ALT, AST, γ-GT, and creatinine levels. Thus, bAgNPs synthesized using Phyllanthus emblica fruit extract hold great promise as nanotherapeutics to combat a broad spectrum of pathogenic bacteria. Future directions may involve further exploration of the potential applications of biogenic silver nanoparticles in clinical settings, including studies on long-term efficacy, extensive in vivo toxicity profiles, and scalable production methods for clinical use.