Molecularly imprinted electrochemical sensor for daidzein recognition and detection based on poly(sodium 4-styrenesulfonate) functionalized graphene

A high sensitive and selective electrochemical sensor for detection of daidzein based on molecular imprinted polymer (MIP) modified electrode was established. The sensitive layer was prepared by electropolymerization of o-phenylenediamine (o-PD)on the surface of Poly (sodium 4-styrenesulfonate)-reduced graphene oxide (PSS-rGO) modified glassy carbon electrode (PSS-rGO/GCE) in the presence of daidzein as a template molecule. The negatively charged poly(sodium 4-styrenesulfonate) units and benzene rings of PSS-rGO can attract positive charged o-PD and provide pi-pi stacking effect of o-PD and daidzein, which makes the compact imprinted film and more imprinted points. The MIP/PSS-rGO composite could specifically recognize daidzein in aqueous solutions which result in the decrease of peak current of K-3[Fe(CN)(6)]/K-4[Fe(CN)(6)] at the MIP/PSS-rGO/GCE. Under the optimized conditions, the decrease of the peak current was linear with the concentration of daidzein in the range of 1.0-20.0 nM. The detection limit was calculated as 0.5 nM (S/N = 3). Relative to the other structurally similar substances, the current response of the MIP/PSS-rGO/GCE toward daidzein was about 6.0, 3.1, 6.9 and 5.2 times higher than those of puerarin, quercetin, genistein and chrysin which suggesting the high selectivity of MIP/PSS-rGO/GCE. The modified electrode was successfully applied to determine daidzein in human serum and pueraria extraction with satisfied recovery suggesting the potential applications in the daidzein determination of clinical samples and nature products. (C) 2017 Elsevier B.V. All rights reserved.