Bio-synthesis of silver nanoparticles with antibacterial activity

Silver nanoparticles (Ag-NPs) have potential applications in life science, food chemistry, biomedicine, photocatalysis and cosmetics fields due to its unique optical, electrical and catalytic properties besides the strong antibacterial property. Apple pomace, a by-product of apple juice production, is ample and easily available. In the present study, this green raw material was used to biosynthesize Ag-NPs for the first time. The obtained silver nanoparticles were investigated by UV–vis, TEM, XRD, and FTIR, respectively. The results showed that the concentration of AgNO3 and the volume ratio of AgNO3 solution to apple pomace extract were the important factors affecting the synthesis of silver nanoparticles. When the concentration of AgNO3 was 10 mmol/L, the volume ratio of AgNO3 solution to the apple pomace extract of 4:1(ν/ν), Ag-NPs were quickly formed. They were stable with high degree of crystallinity. The particle sizes ranged between 10 and 20 nm and the conversation of silver ions was up to 99%. The bacteriostatic circle tests revealed that the biosynthesized Ag-NPs had a strong antibacterial activity against gram positive bacteria and gram negative bacteria. FTIR analysis demonstrated that some bio-molecules with groups of -NH2, -COOH and -OH were distributed on the surface of the newly synthesized Ag-NPs. During the synthesis of silver nanoparticles, there were not any poisonous reducers and stabilizers introduced. [Display omitted] •Apple pomace is used to synthesize silver nano-particles (Ag-NPs) without any poisonous reducer and stabilizer introduced.•The synthesized Ag-NPs covered by biomacromolecules exhibit good dispersibility.•The achieved Ag-NPs have good antibacterial activities for its size less than 20 nm.•The biosynthesis method is cost effectiveness, portability, and environmentally benign.