Self-assembled monolayer as a pre-concentrating receptor for selective serotonin sensing.

We describe a novel medium, a captopril/thiophenol (Capt/TP) mixed self-assembled monolayer (SAM) formed on gold, for selectively pre-concentrating serotonin (5-hydroxytryptamine, 5-HT). The 5-HT molecules were shown to be selectively captured via formation of a strong complex, providing anodic stripping currents upon anodic scan or drastic increases in charge-transfer resistances for a redox probe, Fe(CN)(6)(3-/4-) pair, due to their blocking effects. The 5-HT molecules thus collected were subsequently detected by anodic stripping differential pulse voltammetry (ASDPV) or electrochemical impedance spectroscopy (EIS). The detection limit was 1.2 when detected by EIS and 28 nM with ASDPV. 5-HT was shown to be determined in physiological matrices containing ascorbic acid, dopamine, and other commonly encountered neurotransmitters.