Surface-Enhanced Raman Spectroelectrochemistry with Screen-Printed Electrodes for Quantitative Analysis

Abstract

Electrochemically roughened silver surfaces have been widely employed for Surface-enhanced Raman scattering (SERS) assays. In most cases, the roughening process is usually performed ex situ with a specific electrolyte solution and, afterwards, the analyte is adsorbed on the substrate for the detection. This procedure has several possible issues: the final state of the substrate could not be the optimum for enhancing the SERS effect, the surface could become passivated between the roughening and the detection steps, decreasing the SERS activity, and the step for the analyte adsorption could take several minutes. Moreover, one of the main issues of SERS-based assays is the reproducibility between experiments and these substrates have been mainly used for qualitative studies. However, there is a strong scientific interest for increasing the applicability of SERS assays for quantitative studies with reproducible and simple methods. Screen-printed electrodes could be promising SERS substrates because they are mass-fabricated using the well-established thick-film technology leading to precise, disposable, low-cost and easy-to-use devices. In this work, the real-time in situ electrochemical roughening of readily-available metal screen-printed electrodes is proposed to obtain a quantitative and precise SERS detection of several species at low concentrations using a fast and cost-effective methodology. The roughening and the analytical detection are carried out simultaneously, solving the typical issues of the ex situ preparation. The time-resolved character of this method allows to get dynamic information about the processes leading to a SERS active substrate and correlate them with the microscopic electrode structure at various stages of the substrate preparation. Results show a good linearity between the SERS signals and low concentrations of several species with a good precision between measurements.