Synthesis and characterization of potential fungicidal silver nano-sized particles and chitosan membrane containing silver particles

Silver nano-sized particles were synthesized with strong antifungal activity against the wood staining fungi Ophiostoma flexuosum, O. tetropii, O. polonicum and O. ips. The average size and purity of the nano-sized particles were determined by scanning electron microscopy and XRD spectra, respectively. The structural characterizations of nano-sized particles were performed using IR spectrum and EDS. Radial diffusion method was carried out to reveal the antifungal activity of silver nano-sized particles on MEAagar plates. Strong fungicidal silver nano-sized particles were mixed with chitosan solution and then the chitosan membrane was prepared by solvent evaporation method. Glutaraldehyde was used as cross-linking agent for membrane preparation. Deacetylation degree, concentration and pH of chitosan were considered as a main factor for preparation of bioactive membrane. The quality and structure of membranes were analyzed by Fourier transform infrared spectroscopy. Thermostability of the membranes was confirmed by thermogravimetric analysis. Synthesized chitosan-glutaraldehyde-Ag membrane was tested against the wood staining fungi on MEAagar plates using inhibition zone method. The results showed that the antifun- gal activity of chitosan membrane increased with increasing in concentration of silver nano-sized particles. According to our results, synthesized chitosan membrane has been used as a good carrier for silver nano-sized particles in wood industries and these materials could be very efficient substitutions for chemical preservatives currently used to control fungal contamination in wood industries.