Construction of silver nanoparticles by the triple helical polysaccharide from black fungus and the antibacterial activities

Size controllable silver nanoparticles (AgNPs) were synthesized in situ on the polysaccharides-based nanotubes, which were formed by the triple-helix polysaccharide extracted from black fungus (AF1). The results of transmission electron microscope (TEM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) proved that AgNPs with the size from 10-25 nm were uniformly dispersed on the surface of AF1 dendritic nanotubes without affecting their tubular morphology. Moreover, due to the tubular structure, the loaded silver content of the composites (AgNPs and AF1 nanotube, AF1-Ag) could reach about 50% by thermogravimetric analysis (TG) evaluation. Thus, the smaller size of AgNPs and higher silver loading content suggest that the composites could be applied in the biomedical field. The antibacterial properties of AF1-Ag were evaluated as an example in the present work. As expected, the culture medium contained a few of AF1-Ag (10% ω%, c = 50 μg/mL) exhibited obvious antibacterial properties, and the effect of bacteriostasis increased with the increase of the amount of supported silver content. Taken together, the AF1-Ag with good antibacterial activity and good stability has the potential to be applied in the antibacterial field.