Silver nano-particles: synthesis and characterization by using glucans extracted from Pleurotus ostreatus

Abstract

The extensive use of antibiotics has led to drug-resistant bacteria, which is a major public health issue worldwide. Silver nano-particles have been recognized as efficient broad-spectrum antimicrobial agent. It uses mushroom glucans as reducing and capping agent to reduce its toxicity. In the present work, we performed the characterization of glucans and glucan–AgNPs. The crude glucans were extracted by hot water then fractionated and purified by anion exchange chromatography (DEAE-cellulose 52); the elution of glucans was monitored by phenol sulfuric acid assay. The major fractions were further purified with gel filtration chromatography (Sephadex-G200) then lyophilized. Green synthesis of silver nano-particles was performed by glucans from selected Pleurotus spps. Extracted glucans and synthesized glucan–AgNPs were confirmed by UV–Vis spectra at 190–250 nm and 380–420 nm, respectively. Size of glucan–AgNPs (100.1 nm) was determined by dynamic light scattering. The glucans were characterized by FT-IR, SEM and XRD while glucan–AgNPs were characterized by FT-IR, SEM–EDS, TEM and XRD. Based on FT-IR spectra, the functional groups associated with the glucans and glucan–AgNPs were determined. SEM analysis revealed that the structure of glucan was spongy with asymmetrical particle size while SEM–EDS/TEM analysis revealed the glucan–AgNPs were spherical with size range of 15–45 nm for Pleurotus ostreatus. XRD spectra of glucan showed diffraction peaks at 2θ = 5.9°, 10.1° and 19.6°. By SEM–EDS/TEM analysis, the silver nano-particles against Braggs reflection planes of (111), (200), (220) and (311) in X-ray diffraction, showed diffraction at 2θ = 38.2°, 44.5°, 64.7° and 77.5° in pattern.