Fabrication of Zn–Cu bimetallic MOF-based flexible electrodes for serotonin detection in serum

Serotonin, also known as 5-hydroxytryptamine (5-HT), is a neurotransmitter that plays a vital role in neural activity. An imbalance in 5-HT levels can lead to various physiological and psychological disorders. Hence, accurate detection of 5-HT levels in biological fluids, such as serum, is essential for diagnosing neural disorders. In this study, we developed a simple and customized carbon-cloth electrode coated with a bimetallic (zinc and copper) metal-organic framework (ZnCuMOF) for the electrochemical detection of 5-HT in serum. The synthesized ZnCuMOF exhibited a unique morphology resembling the structure of a bone, as confirmed by scanning electron microscopy and transmission electron microscopy. The functional groups of the ZnCuMOF were examined using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The electrochemical performance of the ZnCuMOF for the sensitive and selective detection of 5-HT was analyzed using cyclic voltammetry and differential pulse voltammetry. The developed sensor demonstrated a wide linear range (0.01-70 μM), a low detection limit (8.5 nM), and good reproducibility. The fabricated sensor was successfully used to accurately and reliably detect 5-HT in serum, with a limit of detection of 20.5 nM. This bimetallic-MOF-based sensor for the detection of 5-HT can pave the way for the development of advanced diagnostic strategies.