Investigation On Electrochemical Sensors For Saccharide And Dopamine Based On Phenylboronic Acid

Phenylboronic acid, as a molecular recognition unit is capable of reversibly binding with glycols substance in an aqueous solution to produce a five-membered or six-membered cyclic ester, has been widely applied for synthesized artificial receptor preparation for detection of saccharide, catechols, glycohemoglobin, bacterial cells. This article is based on boronic acid derivatives on the specific recognition of cis-diol, combining with indicator displacement assay, electrochemical catalytic, and molecular imprinting technology, provideing new ideas for high sensitivity, selective detection of saccharide and dopamine. The main contributions of this artiale are as follows:1. The first chapter summarizes the common types of electrochemical biosensors, the affinity, especially. Boronic acid derivatives as artificial receptors, selective and sensitive detection of monosaccharides, sialic acid, dopamine, sugar, hemoglobin, bacteria, as well as the development and application of molecularly imprinted electrochemical biosensors. Finally, a brief frame of this paper was also introducede.2. 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. 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. The ⊿current were linearly related to D-fructose, D-mannose and D-glucose concentration in the range 5-100 μmol/L (R = 0.993),15-200 μmol/L (R= 0.994), and 20-200 μmol/L (R= 0.987) respectively. The 3σ/S based detection limits of D-fructose, D-mannose and D-glucose were estimated to be 1.2,3.4, and 6.7 μM, respectively.3. A highly selective detection of dopamine electrochemical biosensor was developed by a cross-linking reaction between chitosan film and aminobenzeneboronic acid (APBA), based on the electrostatic interactions. Chitosan film is negatively charged under neutral and alkaline conditions in an aqueous solution, can hinder AA and UA, which negatively charged coexisting with DA, for selective identification and detection of DA. The linear range of detection of DA was 0.001～0.5 mM (n= 6, R2= 0.998), with the sensitivity of 48.0 μA·mM·cm-2 and a detection limit of 0.2 μM (S/N= 3).4. The molecularly imprinted polymer (MIP) film modified glassy carbon electrodes for detection of DA were prepared by electropolymerization of DA,3-hydroxy acid and phenol by cyclic voltammetry. The molecularly imprinted electrochemical sensor has good selectivity for DA recognition. Additionally, the DPV peak current was linear to the DA concentration in the range from 0.002 mM to 0.1 mM (n= 5, R2= 0.995), with the sensitivity of 46.5 μA·mM·cm-2, and a detection limit of 0.3 μM (S/N= 3).