Transition Metal Complexes Based Electrochemical (Bio)Sensors for the Detection of Dopamine

The catecholamine neurotransmitter dopamine is critical in regulating various physiological functions associated with the human central nervous system. Abnormal levels of dopamine in the body can lead to various medical and behavioral conditions. Electrochemical sensors are excellent tools for quantifying dopamine levels in the body due to their sensitivity, lower detection limits, easy operating procedures, and low cost. Chemically modified electrodes are widely used for dopamine detection. Among them, the usefulness of transition metal complexes as electrode modifiers is apparent from their unique structural and electronic features, which resemble active sites of many enzymes. Over the last decade, efforts have been made to develop electrodes immobilizing transition metal complexes for biomolecule sensing. The metal ion and the chosen ligand fundamentally influence the applicability of the sensor. This review provides an overview of the metal complex immobilization strategies as well as various sensors developed for detecting dopamine using transition metal complexes.