Preparation And Application Of Pharmaceuticals Analysis Based On Molecular Imprinted Polymers Electrochemical Sensors

Molecular imprinting technique is becoming increasingly recognized as a powerful technique of synthesizing polymers with recognition specificity to template molecules by manual method. With the significant advantages in easy preparation, high stability, and predictable specific recognition, the synthesized molecularly imprinted polymers (MIPs) have exhibited extensive application prospects in chromatographic separation, solid phase extraction, chemical sensor, and mimetic enzyme catalysis. As a simple, rapid, controllable method, electropolymerization has been employed to construct electrochemical sensors for the determination of substrates. In this paper, different MIPs electrochemical sensors have been fabricated by combining the imprinted and electrochemical sensor techniques. The specific adsorption and selective recognition capabilities of the prepared sensors have been investigated. The results were summarized as follows:1. An electrochemical sensor for theophylline was prepared by electropolymerizing o-phenylenediamine (o-PD) on a glassy carbon electrode in the presence of theophylline, followed by deposition of gold nanoparticles using a potentiostatic method. The morphology of sensor was characterized by scanning electron microscopy (SEM). Under the optimized conditions, the performance of the sensor was studied by differential pulse voltammetry (DPV). The results demonstrated that the MIPs electrochemical sensor not only possessed specific adsorption and high recognition capacity toward theophylline but also could be used to detect theophylline in the concentration range between 4.0×10?7~1.5×10?5 mol/L and 2.4×10?4~3.4×10?3 mol/L, with a detection limit of 1.0×10?7 mol/L(S/N=3). The sensor was also applied in the detection of theophylline in real sample with satisfied result.2. A Multi-walled carbon nanotubes (MWNTs) and Gold nanoparticles (GNPs) composite materials modified electrode was fabricated by depositing MWNTs and GNPs onto a glassy carbon electrode surface through potentiostatic deposition method successively. Then, self-assembly and electropolymerization methods were combined to prepare a caffein MIPs electrochemical sensor onto above modified electrode surface by using p-aminothiophenol (ATP) as a functional monomer. And the morphology of the sensor was characterized by SEM. DPV was used to characterize the adsorption and recognition capabilities of the MIPs sensor. The results showed that the sensor exhibited specific adsorption and high recognition capacity toward caffein in the solution of interfering substances which have the similar structure. The sensor was also successfully used to detect caffein over the range 5.0×10-10~1.6×10-7 mol/L with the detection limit of 9.0×10-11 mol/L (S/N=3).3. A novel thermosensitive imprinted polymers electrochemical sensor composed of theophylline as template molecule and N-isopropylacrylamide as monomer was designed, prepared, and characterized. The influencing factors of sensor's performance, such as the number of scanning cycles, crosslinker and the extracted solution, were investigated and optimized. The experimental results indicated that the thermosensitive imprinted electrode possessed a characteristic ON/OFF switch behavior. And the as-prepared sensor also had a good adsorption and recognition capacities toward theophylline under the room temperature (20°C).