Silver nanoparticles stabilized by tannin grafted collagen fiber: synthesis, characterization and antifungal activity

A novel antifungal nano-silver agent (BT-CF-AgNPs) was synthesized by using bayberry tannin (BT) grafted collagen fiber (CF) as support, and the antifungal behaviors of the nano-silver were investigated by using Saccharomyces cerevisiae as a typical fungus. Bayberry tannin (BT), a kind of natural polyphenol, was grafted onto the CF surface to improve the loading capacity and control the size of the Ag nanoparticles. The main physical and chemical properties of this antifungal agent were characterized by means of Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Ultraviolet-visible Diffusion Reflection Spectrum (UV-DR), X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). It was found that this antifungal agent is in a highly ordered fibrous state. The average diameter of the Ag nanoparticles was 3.78 nm and the nanoparticles were well dispersed on BT-CF. Antifungal experiments demonstrated that BT-CF-AgNPs exhibited high antifungal activity. The number of living cells went down to zero when a cell suspension of S. cerevisiae (105 CFU/mL) was cultivated with BT-CF-AgNPs at 303 K for 14 h. The minimal inhibitory concentration (MIC) of BT-CF-AgNPs against S. cerevisiae was 12 μg Ag/mL. It was observed that the S. cerevisiae cells were damaged after being cultivated with BT-CF-AgNPs, accompanied by the formation of “pits” in the cell wall, while the accumulation of silver nanoparticles in the cell membrane results in the death of the cell. The present investigation indicated that BT-CF-AgNPs can be applied as a new type of antifungal material.