Major depressive disorder is a widespread condition with antidepressants as the main pharmacological treatment. However, some patients experience concerning adverse reactions or have an inadequate response to treatment. Analytical chromatographic techniques, among other techniques, are valuable tools for investigating medication complications, including those associated with antidepressants. Nevertheless, there is a growing need to address the limitations associated with these techniques. In recent years, electrochemical (bio)sensors have garnered significant attention due to their lower cost, portability, and precision. Electrochemical (bio)sensors can be used for various applications related to depression, such as monitoring the levels of antidepressants in biological and in environmental samples. They can provide accurate and rapid results, which could facilitate personalized treatment and improve patient outcomes. This state-of-the-art literature review aims to explore the latest advancements in the electrochemical detection of antidepressants. The review focuses on two types of electrochemical sensors: Chemically modified sensors and enzyme-based biosensors. The referred papers are carefully categorized according to their respective sensor type. The review examines the differences between the two sensing methods, highlights their unique features and limitations, and provides an in-depth analysis of each sensor.

Early detection of colorectal cancer (CRC) significantly improves overall prognosis and increases 5-year survival rates up to 90%. Current non-invasive screening methods for CRC, such as the Faecal Immunohistochemical Test (FIT), have some drawbacks, namely, low sensitivity and a high false-positive rate. The Sialyl-Tn (STn) antigen, frequently expressed in pre-malignant lesions and adenocarcinomas, has been shown to be detected by the novel monoclonal antibody L2A5. In this study, we explored the potential of L2A5 as a non-invasive CRC screening method in an attempt to overcome current limitations. The subjects were categorised into four groups based on colonoscopy findings: no lesion (NL), low-grade dysplasia (LGD), high-grade dysplasia (HGD), and colorectal cancer (CRC). Slot blot analysis using the L2A5 antibody was performed on stool samples from 95 colonoscopy patients. Our findings showed a differential STn expression between the different clinical groups, evidencing excellent discrimination between NL and CRC (AUC, 0.8252; 95% CI: 0.6983–0.9521; sensitivity, 70%). Moreover, moderate discrimination between the NL+LGD and HGD+CRC groups was discerned (AUC, 0.7766; 95% CI: 0.6792–0.8740; sensitivity, 58%). These findings support the application of L2A5 as a tool for detecting STn, allowing for the identification of advanced lesions in non-invasive CRC screening.

Anticoagulants, including warfarin, are often administered to patients who are exhibiting early symptoms of thromboembolic episodes or who have already experienced such episodes. However, warfarin has a limited therapeutic index and might cause bleeding and other clinical problems. Warfarin inhibits the vitamin K epoxide reductase complex subunit 1 (VKORC1), an enzyme essential for activating vitamin K, in the coagulation cascade. Genetic factors, such as polymorphisms, can change the natural function of VKORC1, causing variations in the medication reaction among individuals. Hence, before prescribing warfarin, the patient’s genetic profile should also be considered. In this study, an electrochemical genosensor capable of detecting the VKORC1 1639 G>A polymorphism was designed and optimized. This analytical approach detects the electric current obtained during the hybridization reaction between two 52 base pair complementary oligonucleotide sequences. Investigating public bioinformatic platforms, two DNA sequences with the A and G single-nucleotide variants were selected and designed. The experimental protocol of the genosensor implied the formation of a bilayer composed of a thiolate DNA and an alkanethiol immobilized onto gold electrodes, as well as the formation of a DNA duplex using a sandwich-format hybridization reaction through a fluorescein labelled DNA signalling probe and the enzymatic amplification of the electrochemical signal, detected by chronoamperometry. A detection limit of 20 pM and a linear range of 0.05–1.00 nM was obtained. A clear differentiation between A/A, G/A and G/G genotypes in biological samples was successfully identified by his novel device.

The BDNF gene is associated with high degrees of variability in antidepressant treatments. The Val66Met polymorphism is widely known as a source of this variability, warranting growing interest in genotyping patients that undergo antidepressant treatment to better suit their needs. This paper reports on an electrochemical genosensing platform, based on gold electrodes, capable of detecting this polymorphism, through the use of synthetic enzymatically labeled DNA probes for two different BDNF alleles. The sensor showed promising results, and its applicability to real samples is currently being tested.