A highly selective electrochemical sensor based on surface molecularly imprinted copolymer for the detection of 5-hydroxytryptamine

In this work, a novel composite of Au nanoparticles (Au NPs), ionic liquid (i.e. 1-aminopropyl-3-methylimidazolium bromine, [APMIM]Br) and multi-walled carbon nanotubes (MWCNTs@IL-Au) is prepared through ion-exchange and Au-N coordination between MWCNTs, IL, and Au NPs under mild conditions. The composite is used as support, itaconic acid (IA) and acrylamide (Aam) as functional monomers, 5-hydroxytryptamine (5-HT) as template molecule, ethylene glycol dimethylacrylate (EGDMA) as cross-linking agent and azobisisobutyronitrile (AIBN) as initiator are mixed to synthesize surface imprinted copolymer (DSMIP). The obtained DSMIP-MWCNTs@IL-Au has good conductivity and strong adsorption capacity for 5-HT due to hydrogen bonding and electrostatic interaction. When it is immobilized on a glassy carbon electrode for the electrochemical determination of 5-HT, the resulting sensor presents a wide linear response range (i.e. 0.20-10 mu mol L-1 and 10-400 mu mol L-1) and low limit of detection (i.e. 0.080 mu mol L-1). Furthermore, it shows high selectivity, stability and reproducibility. To evaluate its practicability, the sensor is applied to the determination of 5-HT in human serum and human urine samples, and comparable results are achieved.

Automated summary

A novel composite material with good conductivity and strong adsorption capacity for 5-HT was synthesized, showing wide linear response range and low detection limit in electrochemical determination. The sensor exhibited high selectivity, stability, and reproducibility, and was successfully applied to the detection of 5-HT in human serum and urine samples.