Synthesis of silver nanoparticles with potential antifungical activity for bamboo treatment

To increase the durability of bamboo it is important to find an easy method to fill the micro and meso structure of the biological matrix using a nano-structural material with an antifungical activity. A colloidal solution of silver nanoparticle (Ag-NPs) is a dispersion of metal nanoparticle in water with a diameter between 5-100 nm. Even if the biological mechanism is not completly understood yet, Ag-NPs show a satisfactory bactericidal and antifungical activity. We present a simple and rapid production of Ag-NPs made by a sol-gel synthesis in flow mode by means of microreactor tecnology through a chemical reduction of AgNO3 with NaBH4 in presence of two different organic ligands: sodium/potassium tartrate and trisodium citrate. The synthesis of Ag-NPs in continuous flow compared to the batch technique allowed to reduce the time of synthesis, facilitating the reproducibility of the process and consequently obtaining NPs with more uniform physical and chemical characteristics. The microorganisms of the genus Aspergillus were used for the microbiological tests. The effect of different Ag-NPs on microbial growth was observed daily. In particular, it was shown that the response of the fungus is inversely proportional to the size of the nanoparticles, cell growth is disrupt depending on the proportion between silver and organic ligand and microbialstatic effect, especially in relation to sporulation stage was also observed.