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The authors report on the development of copper nanocluster stabilized with tannic acid (TA CuNC) as a fluorescent nanoprobe for the turn on detection of a catecholamine neurotransmitter, dopamine. The nanocluster is obtained through a microwave assisted synthesis and exhibit distinct blue emission peak at 450 nm during excitation at 370 nm. The luminescence in the present system is effectively quenched by Fe(III) ions. The quenching happens through an electron transfer mechanism, which operate between the nanocluster and Fe(III) ions. The quenching is linear proportional to the concentration of Fe(III) between 0.25 and 1 μM and the detection limit is as low as 1.28 nM. Addition of dopamine into the quenched system causes the removal Fe(III) ions from the cluster surface and thereby leads to the retrieval of luminescence. The quenched system exhibited high sensitivity and selectivity for dopamine with a limit of detection 45 nM. The adaptability of the nanocluster as a turn on fluorescent probe is tested in real samples for the detection of dopamine and the recovery of fluorescence is in the range of 95%. [ABSTRACT FROM AUTHOR]