•Imprinted silica matrix-poly(aniline boronic acid) hybrid is developed for detection of DA.•Amounts of covalent binding sites toward DA are controlled by electropolymerization.•Silica matrix is obtained from aqueous hydrolysis of fluorosilicate in NH3 atmosphere.•Discriminate DA from interferences due to covalent interaction, cavities matching and electrostatic repulsion.A novel imprinted silica matrix-poly(aniline boronic acid) hybrid for electrochemical detection of dopamine (DA) was developed. Boronic acid functionalized conducting polymer was electrochemically prepared on Au electrode. The number of covalent binding sites toward DA templates was controlled by potential cycles. A precursory sol solution of ammonium fluorosilicate (as cross-linking monomer) containing DA was spin-coated on the polymer modified electrode. Under NH3 atmosphere, the hydroxyl ions were generated in the solution and catalyzed the hydrolysis of fluorosilicate to form silica matrix. After this aqueous sol-gel process, an inorganic framework around the DA template was formed and the imprinted hybrid for DA was also produced. As revealed by scanning electron microscopy, UV-vis spectroscopy and cyclic voltammetry characterization, DA was embedded in the imprinted hybrid successfully. The affinity and selectivity of the imprinted hybrid were also characterized by cyclic voltammetry. The imprinted hybrid showed higher affinity for DA than that for epinephrine, and little or no affinity for ascorbic acid and uric acid due to the combined effects of covalent interaction, cavities matching and electrostatic repulsion. The imprinted hybrid sensor exhibited a quick response (within 5 min) to DA in the concentration range from 0.05 to 500 μmol L−1 with a detection limit of 0.018 μmol L−1. The prepared sensor was also applied to detect DA in real samples with a satisfactory result.

•Dopamine cross-linked chitosan film possessing redox-capacitor properties was used as an indicator firstly.•The affinity of the indicator towards FPBA was comparable to that of saccharide towards FPBA in solution.•The interaction of saccharide-FPBA was investigated via a redox-cycling between the indicator and soluble mediators.•A molecular level IMP gate with saccharide and FPBA as inputs was successfully mimicked.Enhanced saccharide electrochemical sensing using dopamine cross-linked chitosan film on the electrode as an indicator was achieved by coupling indicator displacement assay (IDA) with a redox cycling. The affinity of dopamine-chitosan films toward a simple receptor of 2-fluorophenylboronic acid (FPBA) was comparable to that of saccharide towards FPBA in solution. Evidence for redox-capacitor activity of the films was then studied. The electrochemical behaviors of the films binding to FPBA and the competition with saccharide were investigated by cyclic voltammetry. FPBA binding to 1,2-diols on the films blocked electron transfer of a soluble mediator mixture between electrode and the films via a redox-cycling, resulting in a decrease in amplified signal of the mediators. The increase of amplified signal was detected in proportion to the concentration of added saccharide, ascribing to the displaced 1,2-diols from the binding receptor by competition reaction. The sensing strategy was allowed detection of micromolar levels of saccharide. Based on these properties, a molecular level IMP gate with saccharide and FPBA as inputs could be successfully mimicked.

A novel electrochemical approach for detection of saccharides via indicator displacement assay was presented. In this system, 2-fluorophenylboronic acid and dopamine (DA) were performed as probe set. The electrochemical properties of DA and the binding to 2-fluorophenylboronic acid in phosphate buffer at different pH values were investigated by cyclic voltammetry. After addition of fructose to the solution, a competition for the binding 2-fluorophenylboronic acid occurred that led to the release of the DA. The regenerate oxidation current of DA increased with increasing fructose concentration. Under optimized experimental conditions, the peak current was linearly related to fructose concentration in the range of 0.3–5.0 mmol/L with a detection limit of 0.1 mmol/L. In addition, the interaction between 2-fluorophenylboronic acid and other cis-diol compounds such as glucose, galactose and mannose was investigated.A novel electrochemical approach applying the ensemble of 2-fluorophenylboronic acid and dopamine as probe set for detection of saccharides was developed. This approach is simple and robust, since the surface modification of the electrode is not involved and the low potential is operated to the working electrode.