Serotonin level as a potent diabetes biomarker based on electrochemical sensing: a new approach in a zebra fish model.

Serotonin (5-HT) levels have been associated with several exclusively metabolic disorders. Herein, a new approach for 5-HT level as a novel biomarker of diabetes mellitus is considered using a simple nanocomposite and HPLC method. Reduced graphene oxide (rGO) comprising gold nanoparticles (AuNPs) was decorated with 18-crown-6 (18.Cr.6) to fabricate a simple nanocomposite (rGO-AuNPs-18.Cr.6). The nanocomposite was positioned on a glassy carbon electrode (GCE) to form an electrochemical sensor for the biomarker 5-HT in the presence of L-tryptophan (L-Trp), dopamine (DA), ascorbic acid (AA), urea, and glucose. The nanocomposite exhibited efficient catalytic activity for 5-HT detection by square-wave voltammetry (SWV). The proposed sensor displayed high selectivity, excellent reproducibility, notable anti-interference ability, and long-term stability even after 2 months. SWV defined a linear range of 5-HT concentration from 0.4 to 10 µg L-1. A diabetic animal model (diabetic zebrafish model) was then applied to investigate 5-HT as a novel biomarker of diabetes. A limit of detection (LOD) of about 0.33 µg L-1 was found for the diabetic group and 0.15 µg L-1 for the control group. The average levels of 5-HT obtained were 9 and 2 µg L-1 for control and diabetic groups, respectively. The recovery, relative standard deviation (RSD), and relative error (RE) were found to be about 97%, less than 2%, and around 3%, respectively. The significant reduction in 5-HT level in the diabetic group compared to the control group proved that the biomarker 5-HT can be applied for the early diagnosis of diabetes mellitus.

Electrochemical detection of serotonin: A new approach.

Serotonin (5-hydroxytryptamine, 5-HT) is an important neurotransmitter which plays a significant role in various functions in the body, such as appetite, emotions, and autonomic functions. It is well known that biomarker 5-HT levels can be correlated to several diseases and disorders such as depression, anxiety, irritable bowel, and sleep trouble. Among various methods for detecting the 5-HT biomarker, electrochemical techniques have attracted great interest due to their low cost and ease of operation. However, sensitive and precise electrochemical detection of 5-HT levels is not possible using bare electrodes, thus requiring electrode modification. The present review aims to describe the different electroanalytical methods for 5-HT detection using various surface-modified electrodes such as glassy carbon, carbon fiber, diamond, graphite, and metal electrodes modified with conductive polymers. Perspectives and the modification of electrode surface using applied polymers for 5-HT detection have also been presented.

Nanomaterial based electrochemical sensing of the biomarker serotonin: a comprehensive review.

This review (with 131 references) summarizes the progress made in the past years in the field of nanomaterial based sensing of serotonin (5-HT). An introduction summarizes the significant role of 5-HT as a biomarker for several major diseases, methods for its determination and the various kinds of nanomaterials for use in electrochemical sensing process relies principally on a precise choice of electrodes. The next main section covers nanomaterial based methods for sensing 5-HT, with subsections on electrodes modified with carbon nanotubes, graphene related materials, gold nanomaterials, and by other nanomaterials. A concluding section discusses future perspectives and current challenges of 5-HT determination. Graphical abstract Conceptual design of electrochemical sensing process of the biomarker serotonin by using nanomaterials and the role of 5-HTas biomarker in the body from preclinical to clincal.

Ca2+-Switchable Glucose Dehydrogenase Associated with Electrochemical/Electronic Interfaces: Applications to Signal-Controlled Power Production and Biomolecular Release.

An artificial Ca2+-regulated PQQ glucose dehydrogenase (PQQ-GDH) enzyme was electrically connected to conducting electrodes and semiconductor interfaces. Direct electron transfer from the enzyme to the conducting electrode support was stimulated by the addition of Ca2+ cations resulting in reversible enzyme activation. A signal-switchable biofuel cell and biomolecular release have been realized using the Ca2+-activated enzyme immobilized on conducting electrodes. Interfacing the signal-switchable enzyme with a semiconductor chip allowed electronic read out of the enzyme ON-OFF states. The developed approach based on the signal-regulated PQQ-GDH enables numerous bioelectrochemical/bioelectronic applications of the developed systems in signal-activated biosensors and biofuel cells, as well as in biomolecular computing/logic systems.