Gold semicontinuous thin-film-coated mesoporous TiO 2 for SERS substrates
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Gold semicontinuous thin‑film‑coated mesoporous TiO2 for SERS substrates M. Mercedes Zalduendo1 · Paula Y. Steinberg1 · Tomás Prudente2 · Emiliano J. Di Liscia3 · Josefina Morrone1 · Paula C. Angelomé1 · Cristián Huck‑Iriart2 Received: 24 July 2020 / Accepted: 6 October 2020 © Springer Nature Switzerland AG 2020
Abstract In this work, the preparation and thermal evolution of sputtered semicontinuous gold thin films obtained over ordered mesoporous TiO2 films are presented. The controlled surface topography of the ordered mesoporous TiO2 substrate was used as template for obtaining plasmonic hotspots for Surface Enhanced Raman Spectroscopy (SERS) applications. Plasmonic thin film was obtained by Au sputtering when film thickness was under circa 10 nm. Above this value, the porosity effects from the substrate were lost and Raman signal enhancement with it. Moreover, heat treatment was explored in order to obtain gold nanoislands that can also provide very efficient Raman enhancement. Hence, a very straightforward synthesis procedure is presented for sensing application, even for large scale production. Keywords SERS · Mesoporous oxide thin films · Plasmonic films · Sputtering
1 Introduction Surface-enhanced Raman scattering (SERS) spectroscopy is a sensitive technique to characterize, detect and, in some cases, quantify different types of analytes at very low concentrations [1, 2]. SERS based sensing is currently routinely used in several analytical applications ranging from the detection of explosive agents and drugs, to the prevention of documents, medicines and food products falsification, the detection of food contaminants and the quality control [3–5]. Other interesting reported applications of SERS based sensing include the areas of personalized diagnostics [6], immunoassay platforms [7], bioimaging and biosensing [8–10], biomedicine [11], detection
of heavy metal anions and other environmental contaminants [12, 13], among others [14–16]. Most common SERS sensors are built using metallic nanoparticles (NPs) such as gold [17], silver [18], and copper [19], either in solution or supported onto substrates. The enhancement of inelastic scattering by the plasmonic effect in the metallic nanosized particles and films are related to the size, shape, morphology, inter-particle distance and arrangement of the plasmonic nanostructure [20–23]. Mesoporous oxide thin films obtained by the sol–gel process are already employed to design diverse SERS sensors [24]. Ordered mesoporous materials exhibit high porosity where the pore size and order can be modified
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s42452-020-03635-9) contains supplementary material, which is available to authorized users. * Paula C. Angelomé, [email protected]; * Cristián Huck‑Iriart, [email protected] | 1Gerencia Química & Instituto de Nanociencia y Nanotecnología, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, CONICET, Av. Gral. Paz 1499, 1650 San Martín, Bu
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