Molecularly imprinted electroluminescence switch sensor with a dual recognition effect for determination of ultra-trace levels of cobalt (II)

A dual selection/recognition effect is described for cobalt (II) ions (Co 2+ ). It is based on bovine serum albumin-metal-Co 2+ coordination (BSA-Co 2+ ) and the use of a molecularly imprinted polymer (MIP). An electrochemiluminescence (ECL) switch sensor was designed for detecting nanomolar levels of Co 2+ . The BSA-Co 2+ coordination complex was chosen as a template to prepare a MIP modified switch sensor. The coordination reaction between BSA and Co 2+ provides the first step in recognition, and MIP provides the second step for Co 2+ . This leads to a strong improvement in selectivity of the sensor. A multi-walled carbon nanotube/Cu nanoparticles/carbon quantum dots nanocomposite (MWCNT/Cu/C-dots) acts as an ECL device, and the BSA-Co 2+ complex quenches the ECL signal. Therefore, the elution and resorption of BSA-Co 2+ can be used as a switch to control ECL. Additionally, a method was established to detect Co 2+ , with the detection limit as low as 3.07 × 10 −10  mol/L. The method was applied to the analysis of spiked environmental water, soil samples, and agricultural products. The recovery rates of the method were in the range of 87.5–111.3%.