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

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 selectedPleurotusspps. 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 forPleurotus ostreatus. XRD spectra of glucan showed diffraction peaks at 2 theta = 5.9 degrees, 10.1 degrees and 19.6 degrees. 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 2 theta = 38.2 degrees, 44.5 degrees, 64.7 degrees and 77.5 degrees in pattern.