Biogenic one-step synthesis of silver nanoparticles (AgNPs) using an aqueous extract of Persea americana seed: Characterization, phytochemical screening, antibacterial, antifungal and antioxidant activities

Abstract

• Silver nanoparticles were synthesised using Persea americana seed extract in an eco-friendly approach. • The presence of biomolecules such as phenols, triterpenes, phytosterols, flavonoids, and carbohydrates in the extract were identified by a standard phytochemical analysis. • The formation of Persea americana -derived silver nanoparticles were confirmed by a surface plasmon resonance band at 430 nm in UV–Visible spectroscopy. • The as-synthesized green inspired silver nanoparticles were showed good antibacterial, antifungal and antioxidant activities. This study aims to perform a green synthesis of silver nanoparticles (AgNPs) using Persea americana seed. UV–vis, FTIR, XRD, DLS, FE-SEM, EDX and TGA were used for characterizing the AgNPs. The production of AgNPs was primarily observed by change in colour from yellow to reddish-brown and then confirmed by SPR band at 430 nm in UV-vis spectral analysis. FTIR analysis exposed the role of phytoconstituents in the P. americana seed extract as bioreductant, stabilizing and capping agent. In XRD pattern, the major peaks correspond to the planes (2 1 0), (1 1 1), (2 0 0), (2 2 0) (3 1 1) and (2 2 2) which revealed the FCC crystal structure of AgNPs. The average particle size and zeta potential value determined using DLS were found to be 62 nm and − 16.3 mV, respectively. The negative value of zeta potential provides the repulsive force as electrostatic stabilization of AgNPs. FE-SEM images were evidenced the spherical morphology and EDX spectrum revealed a characteristic metallic silver peak at 3.0 keV. We investigated the antibacterial activity of AgNPs against S. pyogenes, P. acnes, E. coli and P. aeruginosa . Our results showed that AgNPs (5.0 mg/mL) were more effective at inhibiting S. pyogenes , P. acnes and E. coli with zone of inhibition of 17.5 ± 0.70, 16.75 ± 1.06 and 9.75 ± 1.06 mm, respectively. We also found that AgNPs had antifungal activity against A. fumigatus . The diffusion of AgNPs into cell wall of microorganism causing morphological distortions and disruption of respiratory functions, which in turn lead to cell death. The synthesized AgNPs have good antioxidant activity with an IC 50 and DPPH radical scavenging rate of 57.67 μg/mL and 70.89 %, respectively. The current study will lead to new antibacterial, antifungal and antioxidant agents in the fields of biomedicine.