Development of impedimetric sensors and biosensors based on screen-printed carbon electrodes for detection of analytes of medical, environmental and industrial interests

Abstract

The advent of sensing technologies for various applications has increased the quality of human life especially for providing sensitive, selective and fast responses. Contrary, traditional analytical assays still face some shortcomings mainly related to high cost, non-portability and lengthy response time. In this context, the present thesis brings the main aspects of sensors and biosensors for application in the medical field, food industry and environmental monitoring, all of them based on the Electrochemical Impedance Spectroscopy (EIS). Due to their electrochemical properties, easiness of modification, low cost and employability in miniaturized systems, screen-printed carbon electrodes (SPCEs) served as transducers in (bio)sensors devoted to recognize horsemeat for meat authentication, glucose and dymethil sulfide (DMS). The SPCE-based immunosensor containing horse immunoglobulin G was capable to selectively detect horsemeat at low concentrations, within a limit of detection (LOD) equal to 0.004%w/v, corroborating its promising application as a tool for screening horse adulteration in raw meat products. The glucose sensor consisting of 3-aminophenylboronic acid as unit of recognition did not detect other sugars nor suffered significant influence of interfering species. Instead, the impedimetric device exhibited a LOD equal to 8.53 x 10^-9 M under an optimized response time of 4.0 ± 0.6 s. In only three minutes, the DMS sensor detected the analyte at a LOD equal to 1.50 x 10^-9 M and provided increasing real-time response towards the target molecule diluted in simulated ocean water. In common, the developed (bio)sensors presented LODs and response times consistent with the real application.