Stoichiometric inhibition of sulfur oxidation triggers dual signals for electrochemical ultrasensitive detection and visualization of monoamine neurotransmitters in MoS2

• Discovery of new electrochemical sensing pathways for quantification of monoamine neurotransmitters. • Realizing electrochemical imaging of dopamine. • Ultrasensitive detection of monoamine neurotransmitters (10 -13 M). • Broadlyresistant to interference from neurotransmitters (GABA, Glu, Gly, ACh) and biomolecules (AA, UA, Lac, Gluc, urea). • Reveal quantized characteristics of dopamine-releasing in PC12 neuron cells. Monoamine neurotransmitters play a key role in regulating neural circuit dynamics, and their imaging and monitoring provide crucial insights for comprehending neural function and diagnosing diseases. However, the current signal generated through the direct electrochemical oxidation of neurotransmitters makes it challenging to achieve their imaging and reliably quantify neurotransmitters at low concentrations. Herein, we introduce a unique electrochemical sensing signal produced by the stoichiometric inhibition of S oxidation in MoS 2 , enabling highly sensitive detection and imaging of monoamine neurotransmitters. The surface S near the defect easily oxidized to produce electronegative −S-S- species under potential, thereby generating a strong current and Raman signal. However, the uptake of stoichiometric monoamine neurotransmitters at the S sites, driven by intermolecular forces, inhibits this oxidation, thus quenching this current and Raman signaling response. This response occurs even at ultralow concentrations (femtomolar level) and effectively excludes interference from amino acid neurotransmitters and other biomolecules. By employing potential-driven Raman mapping, monoamine neurotransmitter can be directly visualized. Furthermore, its high temporal resolution is demonstrated by PC12 neuronal cells achieving rapid synaptic transmission via quantal release within a 50 ms time scale.