Well-designed dopamine-imprinted polymer interface for selective and quantitative dopamine detection among catecholamines using a potentiometric biosensor

We report a well-designed biointerface enabling the selective and quantitative detection of dopamine (DA) using a potentiometric biosensor. To enhance the detection selectivity of DA, a DA-templated molecularly imprinted polymer (DA–MIP) was synthesized on the extended Au gate electrode of a field-effect transistor (FET) biosensor. For a quantitative DA analysis, the thickness of the DA–MIP was controlled to ca. 60 nm by surface-initiated atom transfer radical polymerization (SI-ATRP). In this process, the DA–MIP was copolymerized with vinylphenylboronic acid (vinyl-PBA), inducing molecular charges at the biointerface of the FET gate electrode. These charges were generated by the diol-binding between PBA and dopamine (a catecholamine), and were directly detected as a change in surface potential. In fact, the surface potential at the gate of the DA–MIP-coated FET responded significantly to DA added at concentrations ranging from 40 nM to μM, whereas that of a non-imprinted polymer (NIP)-coated FET hardly changed over this range. Moreover, by measuring the kinetic parameters and electrochemical properties of well-designed devices with various added catecholamines, we confirmed that the DA–MIP-coated FET biosensor selectively and quantitatively detects DA