| Abstract
| - Novel nanocomposite films containing DNA−silver nanohybrids have been successfully fabricated by combineduse of the layer-by-layer self-assembly technique and an in situ electrochemical reduction method with the DNA−Ag+complex as one of the building blocks. UV−vis absorption spectroscopy was employed to monitor the buildup ofthe multilayer films, which suggested a progressive deposition with almost an equal amount of the DNA−Ag+ complexin each cycle. The following electrochemical reduction of silver resulted in the formation of metal nanoparticles inthe film, which was evidenced by the evolution of the intense plasmon absorption band originating from silver.Scanning electron microscopy indicated that the particles formed in the multilayer films possessed good monodispersityand stability, thanks to the surrounding polymers. X-ray photoelectron spectroscopy further confirmed the presenceof the main components (such as DNA and metallic silver) of the nanocomposite films. In addition, we show thatthe size of the metal nanoparticles and the optical property of the film could be readily tuned by manipulating theassembly conditions. Furthermore, the feasibility of the as-prepared nanocomposite films functioning as a surface-enhanced Raman scattering active substrate for sensing purposes was investigated, and the results showed greatenhancement of the Raman signal of two probe molecules, Rhodamine 6G and 4-aminothiophenol.
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