Conformationally Flexible Dimeric-Serotonin-Based Sensitive and Selective Electrochemical Biosensing Strategy for Serotonin Recognition

A novel electrochemical sensor was constructed based on an enzyme-mediated physiological reaction between neurotransmitter serotonin per-oxidation to reconstruct dual-molecule 4,4'-dimeric-serotonin self-assembled derivative, and the potential biomedical application of the multi-functional nano-platform was explored. Serotonin accelerated the catalytic activity to form a dual molecule at the C4 position and created phenolic radical-radical coupling intermediates in a peroxidase reaction system. Here, 4,4' dimeric-serotonin possessed the capability to recognize intermolecular interactions between amine groups. The excellent quenching effects on top of the gold surface electrode system archive logically inexpensive and straightforward analytical demands. In biochemical sensing analysis, the serotonin dimerization concept demonstrated a robust, low-cost, and highly sensitive immunosensor, presenting the potential of quantifying serotonin at point-of-care (POC) testing. The high-specificity serotonin electrochemical sensor had a limit of detection (LOD) of 0.9 nM in phosphate buffer and 1.4 nM in human serum samples and a linear range of 10 to 400 with a sensitivity of 2.0 × 10-2 nM. The bivalent 4,4'-dimer-serotonin interaction strategy provides a promising platform for serotonin biosensing with high specificity, sensitivity, selectivity, stability, and reproducibility. The self-assembling gold surface electrochemical system presents a new analytical method for explicitly detecting tiny neurotransmitter-responsive serotonin neuromolecules.