Enhanced detection of saccharide using redox capacitor as an electrochemical indicator via a redox-cycling and its molecular logic behavior

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.