High-sensitivity copper(II) sensor based on a protein/ion-imprinted polymer cooperative recognition strategy

Despite the promise of ion imprinting technology for the development of electrochemical sensors for heavy metals, improved selectivity and stability are required for practical applications. Herein, a dual recognition strategy based on a protein and an ion-imprinted polymer (IIP) was proposed to develop highly sensitive sensors for copper(II) ions (Cu2+). On Bovine serum albumin (BSA) and graphene oxide (GO)-loaded gold nanoparticles (GO/Au NPs) modify the gold electrode surface, an a Cu2+ IIP was formed on the electrode by electro-polymerization. After Cu2+ was removed from IIP, the imprinted holes with a specific recognition ability for Cu2+ were obtained. In the prepared sensor, Cu2+ recognition sites were present in both BSA and the IIP, thus providing a dual recognition strategy for selective Cu2+ detection. Furthermore, owing to the amplification effect of GO/Au NPs, the sensor showed high sensitivity. With potassium ferricyanide/potassium ferrocyanide as a probe, the logarithm of the Cu2+ concentration was proportional to the sensor current response within the range of 1-8000 x 10-14 mol/L, and the detection limit was 1.12 x 10-15 mol/L. Moreover, for Cu2+ detection in actual samples, the sensor exhibited a recovery rate of 93.2-105.6 %.