AuNi alloy deposited heteroatom-doped porous carbon for the simultaneous detection of biogenic amines.

Simultaneous determination of dopamine, serotonin, and melatonin was demonstrated using a disposable non-enzymatic electrochemical biosensor modified with AuNi alloy-deposited S, N-doped porous carbon. Initially, ZnO/S rich a S, N-doped carbon precursor was synthesized from Zn-rubeanic acid coordination polymer, followed by the acid treatment and pyrolysis under nitrogen to obtain S, N-doped porous carbon (SNPC). Then, a composite layer of benzoic acid functionalized polyterthiophene (pTBA) and SNPC was electrochemically formed (SNPC-pTBA) on the screen-printed electrode with additional subsequent casting of SNPC on the layer, followed by the deposition of AuNi nanoparticles (SNPC-pTBA/SNPC@AuNi) to further enhance the catalytic performance. To optimize the AuNi deposition conditions, the mole ratio, alloy deposition potential and time, SNPC content, and electrolyte pH were changed. Each sensing layer of the final sensor was characterized by electrochemical and surface analysis methods. Under the optimized condition, the proposed sensor exhibited well-defined oxidation peaks at 0.023 V, 0.182 V, and 0.40 V for dopamine, serotonin, and melatonin, respectively. The linear dynamic range was observed over the range 0.25 µM-500.0 µM, with detection limits of 65.8 ± 2.0 nM, 76.1 ± 1.3 nM, and 71.3 ± 2.7 nM for dopamine, serotonin, and melatonin, respectively. The sensor performance was almost unchanged in the presence of other interfering amines and non-amine molecules. The sensing platform reveals stability until 49 days with the relative standard deviation (RSD) of < 7.8%, and the sensor reliability was evaluated by detecting targeted biogenic amines in the real serum samples and the supplement tablet.