In situ growth of polydopamine on surface of covalent organic frameworks under the catalysis of acid phosphatase for dopamine detection

Dopamine (DA) is easy to be oxidized and polymerizes to form polydopamine (pDA) in alkaline conditions, while the synthesis is usually time-consuming (48 h). Herein, the polymerization of DA is completed with 4 h under the catalysis of acid phosphatase (ACP). The high efficiency makes the detection of DA feasibility based on the self-polymerization of DA. In this assay, pDA is grown in situ on the surface of covalent organic frameworks (COFs), and then the fluorescence of COFs is quenched significantly. The linear range of DA is achieved from 0.5–50 μmol/L with a detection limit of 0.16 μmol/L. The detection of DA is not interfered with uric acid, ascorbic acid, and some phenolic compounds, because these substances cannot polymerize in the presence of ACP. Moreover, benefiting from the good sensitivity and selectivity, DA has been successfully determined by this strategy in human urine samples with satisfactory recoveries.