| Molecularly imprinted polymers (MIPs), synthesized in the presence of"imprinting"molecules (the template) by high crosslinking, would bind the target molecules to separate and detect it with extremely high selectivity. Electrochemical detection is simple, rapid and sensitive. Based on the merits of MIPs and electrochemical detection, MIPs electrochemical sensors were prepared by the in-situ polymerization and electropolymerization, respectively. Both of the MIPs performance were analyzed and compared. Carbon fiber microelectrode can be inserted directly into the tissue or cells for in vivo detection, with less damage. MIPs prepared by electropolymerization on surface of carbon fiber microelectrodes were also investigated. The main contents are listed as follows:1. MIPs membrane on the surface of a glassy carbon electrode with the indole-3-acetic acid (IAA) as templet and methacrylic acid as functional monomer was prepared to construct an electrochemical sensor for IAA. Electrochemical oxidation behaviors of IAA on the MIPs modified electrode have been investigated with square wave voltammetry. At oxidation potential of 0.62 V (vs. SCE), the peak currents on the MIPs sensor were proportional to the concentration of IAA in the range of 5.0×10-62.0×10-4 mol/L with the detection limit of 5.0×10-6mol/L (S/N=3), and the RSD of peak current was 1.1% (n=7), the incubation time was 3 min. The MIPs sensor displayed specific selectivity. As relative standard deviation less than 5%, tryptophan, dopamine, ascorbic acid and histidine, 50, 50, 20 and 20 times the amount of IAA, respectively, did not interfere with determination of IAA. The MIPs sensor has been applied to analysis of IAA in soybean sprout and mungbean sprout samples, the average recoveries were between 97% and 100%.2. IAA MIPs membrane on the surface of a glassy carbon electrode was prepared by electropolymerization with IAA as templet and pyrrole as functional monomer. Electrochemical oxidation behaviors of IAA on the MIPs modified electrode have been investigated with square wave voltammetry. With the incubation time of 90 s, the peak currents at oxidation potential of 0.55 V (vs. SCE) recorded with the MIPs sensor were proportional to the concentration of IAA in the range of 5.0×10-6 - 2.4×10-4 mol/L, and the detection limit was 2.0×10-6mol/L (S/N=3). By repetitive determination in the same electrode, the RSD (n=7) of 1.7% showed good repeatability. The MIPs sensor displayed specific selectivity. At relative standard deviation less than 5%, tryptophan, dopamine, ascorbic acid and histidine did not interfere with IAA determination, as it was 20, 20, 20 and 50 times the concentration of IAA, respectively. The MIPs sensor has been applied to analysis of IAA in soybean sprout and mungbean sprout samples, the average recoveries were between 97.1% and 104%.3. Pyrrole-modified carbon fiber electrode was prepared by electropolymerization with IAA as templet . Electrochemical oxidation behaviors of IAA on the MIPs modified electrode have been investigated with square wave voltammetry. With the incubation time of 30 s, the peak currents at oxidation potential of 0.80 V (vs. SCE) recorded with the MIPs sensor were proportional to the concentration of IAA in the range of 5.0×10-6 - 1.4×10-4 mol/L, and the detection limit was 2.5×10-6mol/L (S/N=3). By repetitive determination with the same electrode, the RSD (n=7) of 1.7% showed good repeatability. The MIPs sensor displayed specific selectivity. As tryptophan, dopamine, ascorbic acid and histidine was 20, 20, 50 and 50 times more than IAA, respectively, they did not interfere with IAA determination, at relative standard deviation less than 5%. The MIPs sensor has been successfully applied to analysis of IAA in soybean sprout samples in vivo... |
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