Electrochemical serotonin sensing interface based on double-layered membrane of reduced graphene oxide/polyaniline nanocomposites and molecularly imprinted polymers embedded with gold nanoparticles

• The membrane of rGO/PANI was prepared for enhancing the sensitivity of sensor.
• Functionalized AuNPs were proposed to fabricate the conductive AuNPs@MIPs.
• The sensor could avoid the interferences caused by AA, DA, UA, and EP.
• The sensor was used for sensitive and selective detection of 5-HT in real samples.

A double-layered membrane sensing interface was fabricated for sensitive and selective detection of serotonin (5-hydroxytryptamine, 5-HT) based on reduced graphene oxide (rGO)/polyaniline (PANI) nanocomposites and molecularly imprinted polymers (MIPs) embedded with gold nanoparticles (AuNPs). rGO/PANI nanocomposites were synthesized via electro-deposition process, in which protonated anilines were first anchored on the rGO sheets through electrostatic adsorption, and then the rGO/PANI membrane was formed on the bare electrode via cyclic voltammetry method. Functionalized AuNPs (F-AuNPs) were prepared to fabricate the MIPs embedded with AuNPs (AuNPs@MIPs) membrane on the modified electrode by constant potential method in the presence of 5-HT and p-aminothiophenol. The materials prepared in this work were examined by ultraviolet-visible (UV-Vis) and Raman spectroscopy, and the as-prepared membranes were characterized by scanning electron microscope, energy dispersive spectroscopy, and electrochemical methods. In addition, the obtained sensor allowed remarkable selectivity to 5-HT against the interferences caused by ascorbic acid and other interferents. A linear dependence of peak current in differential pulse voltammograms was obtained over 0.2-10.0 μmol L−1 5-HT with the limit of detection of 11.7 nmol L−1 (S/N = 3). Furthermore, the obtained biomimetic sensor was employed to detect 5-HT in human serum samples.