Silver nanoparticles encapsulated in glycogen biopolymer: Morphology, optical and antimicrobial properties

The glycogen biopolymer from the bovine liver has been used as stabilization agent for the growth of silver nanoparticles. The samples with various contents of silver were prepared by two different procedures that include fast (using microwave radiation) and slow (conventional) heating of the reaction mixtures. The TEM images of the two nanocomposites showed the presence of nanoparticles with average diameter of 9.7 and 10.4 nm, respectively. The results also revealed that the optical properties of the obtained nanocomposite samples strongly depend on the method of preparation. The samples prepared using microwave radiation exhibited narrower surface plasmon resonance peaks, while the silver nanoparticles induced quenching of the photoluminescence of glycogen in all of the tested samples. Antimicrobial activity tests were carried out against Staphylococcus aureus, Escherichia coli and Candida albicans pathogens and showed that the microbial growth was gradually reduced as the concentration of the silver increased. Also, after 2 h of exposure to the nanocomposites the number of cells was significantly reduced (>99%) for all the strains tested.