Preparation and characterization of polyoxometalate-Ag nanoparticles composite multilayer films

The multifunctional thin films (BW12/Ag NPs)(n), (BW12=BW12O40, NPs=nanoparticles) were prepared by layer-by-layer self-assembly method. The (BW12/PEI-Ag+)(n) (PEI=polyethylenimine) composite films were achieved through alternately depositing anionic BW12 and cationic PEI-Ag+ complex. The deposition process of (BW12/PEI-Ag+)(10) multilayer is linear layer-by-layer self-assembly. Under UV irradiation, Ag ions in (BW12/PEI-Ag+)(n) multilayer films were reduced photochemically into Ag NPs and (BW12/Ag NPs)(10) films were obtained. Through UV vis measurements, the presence of surface plasma absorption peak at 445 nm demonstrated the formation of silver NPs. The electrochemical and antibacterial activities of (BW12/Ag NPs)(n) films were investigated. The electrochemical results indicate that the glassy carbon electrode modified with (BW12/Ag NP)(n) film exhibits the electroreduction toward O-2. Moreover, the (BW12/Ag NP)(10) multilayer films exhibit long-lasting antibacterial properties toward Escherichia coli (E. coli). (C) 2010 Elsevier B.V. All rights reserved.