| Molecularly imprinted polymers (MIPs) have the three remarkable characteristics of pre-definiteness, special identification and practicality. Meanwhile, MIPs have the advantages of cost cheap, anti acid and alkali, resistant high temperature and pressure. Thus, it was widely applied to solid phase extraction, sensor, drug synthesis, immunoassay and catalysis, etc. Electrochemical sensor have the superiority of cost cheap, low detection limit and simple preparation. Therefore, using MIPs as recognition element gradually increases. Crosslinking agent as the important part of MIPs, species of MIPs is the key to the successfully synthesis of MIPs. At present, crosslinking agent was almost small molecular reported in literature, and existing in the shortcomings of difficulty in eluting template molecule, long response time, the high detection limit and so on, it restrict the application of MIPs in electrochemical sensor. Thus, exploration on the novel crosslinking agent to expand the application of electrochemical sensor is the trend of molecular imprinting technique.This paper take rosin which is the characteristic resources in guangxi as material, rosin obtained modified rosin namely malay rosin acrylic acid glycol ester in the modification process. Using it as crosslinking agent and the different natural drug as template molecule, take advantage of situ initiated polymerization by heating (free radical polymerization). Construction of three new model current source electrochemical sensor make use of malay rosin acrylic acid glycol ester as crosslinking agent for the first time. The main contents are as follows: (1) MIPs was synthesized by using ligustrazine hydrochloride (LH) as template, acrylic acid as functional monomer and self-made modified rosin(burial rosin acrylic acid glycol ester) as cross-linking agent based on the molecular imprinting technique, and a molecularly imprinted sensitive membrane was constructed on the surface of a glassy carbon electrode using traditional system for the determination of ligustrazine Hydrochloride by free radical polymerization method in neutral condition. Potassium ferricyanide considers as the probe of solution. The MIPs membrane was characterized by cyclic voltammeter (CV), differential pulse voltammeter (DPV) as well as electrochemical impedance spectroscopy (EIS). In optimized conditions, when using the incubation time of 4s, the reduced peak currents of potassium ferricyanide were proportional to the concentration of LH in the range of 3.0×10-7 to 1.2×10-5 mol/L and 1.3×10-5 to 2.7×10-5 mol/L with a detection limit of 1.0×10-7 mol/L (S/N=3). The MIPs sensor showed high reproducibility (RSD=0.48%) and stability. Determination of LH in ligustrazine hydrochloride injection showed good recovery.(2) A MIPs was synthesized by using self-made burial rosin acrylic acid glycol ester contains the skeleton of phenanthrene rings as cross linking agent, quercetine (Qu) as template and methyl methacrylate as functional monomer based on the molecular imprinting technique, and a molecularly imprinted sensitive membrane was constructed on the surface of a glassy carbon electrode for the determination of quercetines using free radical polymerization method. Potassium ferricyanide considers as the probe of solution. The MIPs sensor was tested by cyclic voltammeter (CV) as well as differential pulse voltammeter (DPV) to verify the changes in currents of ferricyanide. In optimized conditions, when using the incubation time of 36s, the reduced peak currents of potassium ferricyanide were proportional to the concentration of quercetine in the range of 2.3×10-5 to 1.0×10-3 mol/L with a detection limit of 8.6×10-6 mol/L (S/N = 3). The MIPs sensor showed high reproducibility (RSD = 1.00%) and selectivity. Determination of Qu in acanthopanex injection showed good recovery.(3) MIPs was synthesized by using rutin (Ru) as template, modified rosin(burial rosin acrylic acid glycol ester) contains the skeleton of phenanthrene rings as cross linking agent and methyl methacrylate as functional monomer based on the molecular imprinting technique. A molecularly imprinted membrane was constructed on the surface of a glassy carbon electrode for determination of Ru using free radical polymerization method. The response characteristics of Ru sensor were studied on electrochemical impedance spectroscopy (EIS) as well as cyclic voltammeter (CV). When using the incubation time of 2 min, the response of peak currents were linear to the concentration of Ru in the range of 2.2×10-5 to 1.5×10-3 mol/L with a detection limit of 1.2×10-6 mol/L (S/N = 3). The MIPs sensor showed high reproducibility (RSD = 1.21%) and selectivity. The sensor has been applied to the analysis of Ru in troxerutin injection samples with recovery rates ranging from 96 % to 101.3%.(4) The chemically modified electrode of poly-molested-multiwalled carbon nanotube (MWCNT) functionalized with carboxylic group coated glassy carbon electrode ((PMHE-MWCNTs/GC)) has been prepared. The electrochemical behavior of uric acid (UA) and its determination method has been studied. It was found that modified electrode exhibited a remarkable catalysis and sensitizing effect for the oxidation of uric acid in the solution of 0.3 mol/L HAc-NaAc (pH 4.65). The oxidative peak negative potential was shifted from 0.573 V to 0.5 V (vs. AgCl/Ag), and the sensitivity increased with 6 times. In optimized conditions, the determination range was from 1.0×10-6 7.0×10-4 mol/L (r = 0.9968) with a detection limit of 1.0×10-7 mol/L. The method has been used to determine the content of uric acid in human urine.(5) A new method for the determination of ligustrazine (LZC) was found based on the Nafion (NF)-multiwalled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE/Nf-MWCNTs). It was found that LZC had current peak of reduction both on bare glassy carbon electrode and carbon nanotubes modified glassy carbon electrode in the solution of 0.01 mol/L KCl～HCl(pH=2.00). Compared with bare glassy carbon electrode, multiwalled carbon nanotubes modified glassy carbon electrode exhibited a remarkable catalysis and sensitizing effect for the LZC. The reduction peak potential of LZC shifted positively from -0.628 V at bare GCE to -0.598 V at GC/Nf-MWCNTs, and the sensitivity increased with 4 times. The reduced peak currents were proportional to the concentration of LZC in the range of 1.0×10-7 1.2×10-4 mol/L(r=0.9996) with a detection limit of 1.0×10-8 mol/L by using differential pulse voltammeter. The electrochemical behaviors of LZC were studied, and the system was two proton numbers(X=2) and two electron numbers (n=2). This method has strong anti-interference ability and has been used to determine the content of LZC in medical tablets. The recovery was 99.0～101.0% by means of standard addition method. |
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