▎ 摘　　要

Neurotransmitter dopamine (DA) has been implicated in a variety of physiological and pathological processes, realizing its low detection limit and high sensitivity analysis is of great significance for early disease diagnosis. Herein, we propose a simple pyrolysis approach for dispersing Fe-sites onto the N-doped graphene support (denoted as Fe/N-GR) to construct an electrochemical biosensor for DA detection. The fully exposed Fe-sites guaranteed the well-defined active center for electrochemical oxidation of DA. The Fe/N-GR electrochemical biosensor achieves an ultra-low detection limit for DA of 27 pM with a linear range of 50 pM-15 nM. Specifically, the Fe/N-GR electrochemical biosensor exhibits favorable sensitivity and enzyme-level molecular identification ability in the selective detection of DA versus other typical redox-active interferents. What's more, the detection of dopamine in real human serum samples verifies the applicability of the developed sensor. Our results demonstrate a promising means of using fully exposed metal-site subnanometric catalysts for electrochemical sensing applications.