Silver nanoparticles/nanostructured TiO2 interface: a photo-renewable “silver-ions electrode” for neurotransmitters detection

In recent years the use of hybrid nanomaterials, characterized by unprecedented behaviours and features, has paved the way towards promising applications in many fields. The synergistic functionalities provided by these nanocomposites, based on the generation of heterojunctions, allow to obtain “brave new materials”, with physico-chemical properties which are not only the sum of the precursors’ ones. Although the Literature has used plenty of these new devices for different applications, the complete understanding of the phenomena deeply located inside these interfaces is still to be clarified. In this context, we propose this theoretical and electrochemical concerted study to help in the understanding of the Ag-TiO2 interface properties. In particular, silver nanoparticles were embedded in a TiO2 (anatase polymorph) photoactive layer in a sandwich-like nanostructured electrode, which was (photo)electrochemically characterized by cyclic voltammetry and electrochemical impedance spectroscopy. According to the theoretical and experimental findings it could be concluded that the device may be considered as a “positively charged silver nanoparticles-based electrode”, with positively ionized surface silver atoms protected by the titania layer, which holds a partial negative charge. The final sensor performed efficiently in the electroanalytical determination of some neurotransmitters in simulated biological matrices presenting interesting results in terms of sensitivities, detection limits and photoactivity, providing also the first photo-renewable sensor device, capable of overcoming the fouling and passivation of the electrode surface, an unavoidable drawback during the detection of this kind of analytes [1-3]. Acknowledgments This work has been supported by Fondazione Cariplo (Italy), grant no. 2014-1285 and by the MIUR National Project PRIN 2012 (prot. 20128ZZS2H). References 1. G. Soliveri, V. Pifferi, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, K. Sparnacci, L. Falciola, Analyst, 2015, 140, 1486-1494. 2. V. Pifferi, G. Soliveri, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, L. Falciola, RSC Advances, 2015, 5, 71210-71214. 3. V. Pifferi, G. Soliveri, G. Panzarasa, G. Cappelletti, D. Meroni, L. Falciola, Anal. Bioanal. Chem., 2016, 7339-7349.