A highly selective and sensitive biosensor for dopamine based on a surface molecularly imprinted layer to coordinate nano-interface functionalized acupuncture needle

The quantification of dopamine (DA) in clinical samples and tracking its dynamic changes from living cells is not only critical for clinical blood examination but also important to understand its role in cellular physiology. A new functionalized microneedle electrode is fabricated with 4-mercaptophenylboronic acid (4-MPBA) and a polymeric additive (acid chrome blue K, ACBK) to achieve a dual-recognition molecular imprinted interface. DA molecules could perform suitable configuration for fluent electron-transfer via cyclic borate inter-reaction between boric acid group of anchored 4-MPBA and the hydroxyl group, and ACBK should be gradually electropolymerized around the DA molecules and adhering to the electrode surface. The obtained interface with imprinted cavity is highly selective to DA molecules, which may be attributed to the dual-recognition site of 4-MPBA and the complementary cavity shape, leading to an unobstructed electron-transport pathway through 4-MPBA and the gold nanoparticles (AuNPs) for the captured DA. The properties of the prepared microneedle electrodes are characterized via electrochemical techniques. Under optimum conditions, the sensor exhibits outstanding performance for detecting DA with good linearity in a broad range of 5 × 10-7 mol/L to 1.0 × 10-3 mol/L with a detection limit of 1.4 × 10-7 mol/L (S/N = 3). Furthermore, the fabricated sensor is successfully applied to analyze DA in serum and can achieve real-time monitoring of DA released from PC12 cells stimulated by K+.