This project deals with the investigation into biogenic amines and polyamines sensors (biogenic amines, BAs), that are of interest in different areas, such as food, when linked to growth of bacteria, and medicine, when linked to carcinomas. The sensors will be characterized primarily by electrochemical techniques, morphological analysis (SEM) and Raman spectroscopy (via surface-enhanced Raman scattering, SERS) and by detecting BAs from the formation of peroxide hydrogen (H2O2). Different Au substrates will be prepared (disks and/or films deposited on glass slides), which will surface treated in order to increase porosity and then, decrease leaching effects from materials deposited on the surface, but without blocking the entry of analytes. It is expected that nanoporous Au substrates (NPG, nanoporous gold) will improve the sensor performance with reference to its response into the detection of BAs. The following substrates will be studied here: i) NPG; II) NPG/metalalic eletrodeposited nanoparticles, iii) NPG/Raman reporter molecule; all samples will analysed before and after enzyme immobilization (e.g., diamine oxidase). The measurements will be carried out in standard solutions of H2O2 and commercially acquired BAs such as histamine, putrescine, spermidine and spermine; afterwards, urine samples can be also tested. In order to determinate the optimum conditions for sensor preparation, initially the analysis method will be electrochemistry, by measuring reduction currents. Afterwards, the detection will be optical by using SERS, when it will be expected to achieve low values of detection limit and overcome one of the major problems in electrochemical sensors of H2O2, which is the presence of interfering species due to the high operational potential in amperometric measurements. At the final part of the project, it is intended to use the sensors in miniaturized devices with microfluidic technologies and integrated SERS, and then, obtain more selective and rapid responses in simultaneous analysis of BAs.
News published in Agência FAPESP Newsletter about the scholarship: