The properties of confined liquid water, or liquid water in contact with hydrophobic surfaces, are significantly different from those of bulk liquid water. However, all of water's commonly described properties are related to inert "bulk liquid water" which comprises a tetrahedral hydrogen-bonded network. In this work, we report an innovative and facile method for preparing small water clusters (SWCs) with reduced affinity hydrogen bonds by letting bulk water flow through supported Au nanoparticles (NPs) under resonant illumination to give NP-treated (AuNT) water at constant temperature. Utilizing localized surface plasmon resonance on illuminated Au NPs, the strong hydrogen bonds of bulk water can be disordered when water is located at the illuminated Au/water interface. The prepared SWCs are free of Au NPs. The energy efficiency for creating SWCs is ∼17%. The resulting stable AuNT water exhibits distinct properties at room temperature, which are significantly different from the properties of untreated bulk water, examples being their ability to scavenge free hydroxyl and 2,2-diphenyl-1-picrylhydrazyl radicals and to effectively reduce NO release from lipopolysaccharide-induced inflammatory cells.

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In this study, polypyrrole (PPy) films were electrochemically deposited on gold substrates roughened by a triangular-wave oxidation-reduction cycle (ORC) in an aqueous solution containing 0.1 N KCl. The results indicate that the intensity of surface-enhanced Raman scattering (SERS) of PPy significantly depends on the ORC scans. Correspondingly, the superficial complex formed on the roughened gold has a strong influence on the SERS effect. The optimum Raman signal of PPy deposited on Au roughened with 25 scans in ORC is ca. 300 times larger than that of PPy deposited on Au without ORC treatment. Meanwhile, the (220) face of Au partly changes into the (111) face with the lowest surface energy after ORC roughening. Toward higher frequency, a shift of CdC backbone stretching of PPy situated at ca. 1575 cm -1 in the SERS spectrum was found which is attributed to interfacial charge transfer from electrodeposited pyrrolylium nitrogen to the roughened gold. Furthermore, this study shows that the SERS enhancement of PPy electropolymerized on roughened Au mainly arises from the chemical effect between PPy and the Aucontaining complex.

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