Development of a molecularly imprinted electrochemiluminescence sensor based on bifunctional bilayer structured ZIF-8-based magnetic particles for dopamine sensing

A bilayer-structured ZIF-8 composite with dual functions of sensing and recognition was synthesized, with ZIF-8 serving as an electrochemiluminescence (ECL) probe carrier and molecularly imprinted membrane to construct a molecularly imprinted electrochemiluminescence sensor. The inner layer was a ZIF-8 layer loaded with a lumines-cent probe, which was obtained by the reaction of zinc ions with 2-methylimidazole on the magnetic Au@CoFe2O4 surface in the presence of Ru(bpy)3 2+, the composite magnetic particle is marked as ZIF(Ru)/Au@CoFe2O4. The outer layer was a layer with recognition function using ZIF-8 as an imprinted membrane, which was obtained by a layer-by-layer self-assembly method on the surface of ZIF(Ru)/Au@CoFe2O4 with dopamine (DA) as a template molecule, which was marked as ZIF(MIP)/ZIF(Ru)/Au@CoFe2O4. After eluting the template molecules, the com-posite particle was immobilized on the surface of a magnetically controlled glassy carbon electrode (MGCE) to obtain a molecular imprinting (MIP) modified electrode. When dopamine molecules were re-adsorbed by the MIP, a charge/energy transfer between dopamine and Ru(bpy)3 2+ occurred. It subsequently led to the quenching of electrochemiluminescence, which was used as the basis for the detection of dopamine by a molecularly imprinted electrochemiluminescence sensor. When the dopamine concentration was in the range of 1.0 x 10- 14 -5.0 x 10 - 10 mol/L, the ECL intensity change of the sensor and the dopamine concentration had a good linear relationship, and the detection limit was 4.8 x 10 - 15 mol/L. The molecularly imprinted electrochemiluminescence sensor was successfully applied to the detection of dopamine in human serum samples.