In Situ Preparation And Antibacterial Activity Of Silver/Polydopamine/Pulp Fibers Composites

Nano silver/polydopamine/pulp fibers (nanoAg/PDA/PF) and silver(silver oxide)/polydopamine/pulp fibers (Ag(AgO)/PDA/PF) antibacterial papers were prepared via in situ chemical polymerization by two-pot method and one-pot method, respectively, and by evaluating the antibacterial activity against gram positive bacteria (S. aureus) and gram negative bacteria (E. coli), the effect of preparation conditions such as reaction pH, dopamine concentration, silver nitrate concentration and polymerization reaction time on antibacterial activity and strength properties of paper was studied. Some instrumental analysis methods such as SEM-EDX, XRD and TGA were used to analyze and characterize the composites.The antibacterial activity of the composite was strongly correlated with deposition ratio of PDA-nanoAg or PDA-Ag(AgO) particles. The results showed that the higher the deposition ratio of PDA-nanoAg or PDA-Ag(AgO) particles, the better the antibacterial activity of paper. Under the conditions of pH8.5, room temperature, dopamine (DA) 125 mg/L, silver nitrate (AgNO3) 375 mg/L and dopamine polymerization 2 h, the nanoAg/PDA/PF antibacterial paper with optimal antibacterial activity could be obtained by two-pot method. The optimal preparation conditions of Ag(AgO)/PDA/PF antibacterial paper by one-pot method were:pH 10.5, room temperature, dopamine 312.5 mg/L, silver nitrate (AgNO3) 750 mg/L and 4 h.The antibacterial paper prepared was observed by SEM. The results showed that some spherical and cubic silver nanoparticles were deposited on the surface of pulp fibers. The element content of the antibacterial paper prepared under the optimal conditions was also measured by EDX. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and thermogravimetric (TGA) analyses confirmed that silver nanopartiles were in situ generated and deposited on the polydopamine functionalized pulp fibers surface.By comparing the two kinds of antibacterial papers, they both had their own advantages. On the one hand, nanoAg/PDA/PF antibacterial paper prepared by two-pot method possessed relatively brighter color and better mechanical strength, but the antibacterial activities against gram positive bacteria (S. aureus) and gram negative bacteria (E. coli) were relatively weaker. On the other hand, Ag(AgO)/PDA/PF antibacterial paper prepared by one-pot method had the relatively stronger antibacterial activities against gram positive bacteria (S. aureus) and gram negative bacteria (E. coli), but the color was deeper, and the tensile strength was lower.The objective of this study was to prepare paper-based functional materials with antibacterial activity by using two-pot method and one-pot method under simple, mild and green conditions. Utilizing the broad-spectrum antibacterial properties of dopamine-modified silver nanoparticles, the added value of paper products could be further increased. This study could provide a theoretical guidance for the research and development of novel antibacterial paper product.