Study On Molecularly Imprinted Electrochemical Sensors

With the development of molecular imprinting technology, molecularlyimprinted polymers (MIPs) become an important synthetic material because of itsease of preparation, low cost, thermal stability, physical robustness and excellentselectivity. A new generation of electrochemical sensors which is modified by MIPshas attracted people’s attention due to high sensitivity, low cost, easy miniaturization.However, the traditional preparation methods with poor biocompatibility,difficult film forming process, slow signal response and other shortcomings limitedthe application of MIPs. So how to prepare molecularly imprinting electrochemicalsensors in a relatively easy way to get quick respond and good biocompatibility withsensitivity and selectivity is still an important research topic. There are many smallbiological molecules impact the health of human body, including amino acids and avariety of body neurotransmitters. Among them, epinephrine is an importantneurotransmitter catechu naphthol. Many human life phenomena have an importantrelationship with the concentration of epinephrine. Adrenergic drugs can be used toanaphylactic shock, bronchial asthma and heart disease. Additional, tyrosine is anessential amino acid in human body which takes part in the synthesis of proteins andcatecholamine. Therefore, it is essential to determinate the level of tyrosine in manyfields such as biochemistry, pharmaceutical and clinical analysis.Accordingly, we combine electrochemical sensor and the excellent properties ofmolecular imprinting polymers to prepare excellent molecularly imprintedelectrochemical sensors to detect epinephrine and tyrosine respectively byelectrodeposition chitosan method. Chitosan as a biological polymer, with goodbiocompatibility and film-forming properties, is rich in functional groups, which canbe used as a novel functional monomers and crosslinkers for target molecule in theconstruction of the molecular imprinted electrochemical sensor. To enhance the selectivity and sensitivity of the electrode, we introduced multi-walled carbonnanotube (MWNTs), poly ionic liquid (PIL) and β-cyclodextrin into the imprintedfilm. The specific contents are as follows:(1) We reported a sensor for epinephrine that was based on an ITO electrodemodified with multi-walled carbon nanotubes pre-coated with a polymerized ionicliquid (PIL-MWNTs). A chitosan film was then electrodeposited on the ITO electrodein the presence of epinephrine (the template) and PIL-MWNTs. This film acted as anexcellent recognition matrix due to its excellent film-forming ability and the manyfunctional groups that favor hydrogen bond formation with the target molecular. ThePIL-MWNTs, in turn, can improve the sensing performance due to their goodelectrical conductivity, high dispersity, and large surface area. We studied the processof the preparation of the electrode and the impact of various materials to the electrodeperformance. The imprinted sensor was applied to the detection epinephrine andachieved good results.(2) A facile molecularly imprinted sensor for tyrosine electrochemical sensingwas developed, based on electrodeposition of chitosan film in the presence ofβ-cyclodextrin and tyrosine template on the surface of ITO modified by MWNTs. Inthis configuration, chitosan was utilized to form a recognition matrix. Meanwhile, theintroduced MWNTs and β-cyclodextrin exhibited noticeable enhanced selectivity andsensitivity to tyrosine. This paper systematically studied the effects of variousmaterials during the preparation of the sensor, the detection performance of the sensorto tyrosine, and optimized the experimental conditions. The sensor for the detection oftyrosine showed good selectivity and sensitivity.