Combined With Molecular Imprinting Technique And An Electrochemical Sensing Technology And Its Application

The preparation of a variety of molecular imprinted polymer(MIP)modified electrochemical sensor,and used for antibacterial drugs and biological endogenous substances detection,the molecular imprinted polymer modified on the surface of high surface area,high conductivity of 3D nano materials,construction of nanostructured electrodes with specific recognition ability for the determination of biological active substances of dopamine.The specific work is summarized as follows:(1)A molecularly imprinted polymer decorated glassy carbon electrode(MIP/GCE)is facilely developed into an electrochemical sensing platform for detection of metronidazole(MNZ).MIP preparation was carried out via in situ electropolymerization and o-phenylenediamine(o-PD)was selected as the optimal functional monomer.Cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS)were employed to characterize and assess the performance of the as-obtained sensor.In particular,two assay methods,which are based on different principles,were involved in the detection procedure.One is based on MIP/catalysis(Method ?)and the other is MIP/gate effect(Method ?).Comparison of these two methods was made in the aspects including detection range,sensitivity,accuracy,selectivity,repeatability and long-term stability.It is found that Method ? affords lower detection limit of 3.33×10-10 mol/L(S/N=3)while the detection limit of Method ? is 6.67×10-10 mol/L(S/N=3).The linear range of Method ? and ? is1.0×10-9 to 1.0×10-8 mol/L and 2.0×10-9 to 1.0×10-7 mol/L,respectively.The MIP/GCE exhibits good recognition ability towards the template molecule-MNZ in the presence of the analogues of MNZ and other interferents,which can be ascribed to the successful imprinting effect during MIP membrane preparation.(2)Herein a pair of molecularly imprinted polymer(MIP)modified electrochemical sensors were reported to detect glutathione(GSH)and glutathione disulfide(GSSG)in arsenic trioxide-treated HL60 cells.MIP film was in situ synthesized onto electrode surface via electro-polymerization in a facile way.The characteristics of the obtained sensors were investigated by cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS).Both GSH-MIP and GSSG-MIP sensors exhibit the relatively wide linear detection range and low detection limit of 1.33×10-10 mol/L(S/N=3).It is found that N-acetylcysteine and DL-homocysteine,the precursors of GSH,show little influence on the detection of glutathione species,nor did the reactants of arsenite and GSH.Such strategies were successfully applied to discriminate GSH and GSSG in cell samples with acceptable recoveries of 92.0~109.1%,and the results are comparable with classic o-phthalaldehyde fluorospectrophotometry.Moreover,the presented sensors allow for easy disclosure of the reversion of malignant phenotype in leukemia cells via glutathione species analysis.(3)The 3D composites formed by Graphene foam(GF)and carbon nanotube(CNT)were used as the working electrode,and the molecularly imprinted polymer(MIP)was modified on the surface to construct3 D nano-structured electrochemical sensor for the detection of dopamine in biological samples.The composite nano-materials(CNT/GF)were prepared by plasma-enhanced chemical vapor deposition(CNT and GF)on the surface of the composite nano-materials(CNT/GF)using a nickel mesh as a template.After processing,the electrochemical sensors(NIP/CNT/GF)was fabricated by polymerizing a layer of molecularly imprinted polymer with DA as template molecule on the surface of CNT/GF.At the same time,the non-molecular imprinting polymer-modified composite electrodes were prepared for comparison.The outstanding advantages of the composite electrode are: 1)it does not depend on the electrode,in the commercialization of cost savings;2)CNT/GF electrode has 3D structure as MIP substrate has expanded sensor surface area,thereby increasing the sensitivity of electrodes;3)MIP provides excellent performance for the molecular recognition of the sensor system,which ensures the selectivity of the electrode.The results showed that the current shift had a good linear relationship with the concentration of DA in the range of 2×10-15~1×10-12 mol/L,and the detection limit was 6.67×10-16 mol/L(S/N=3).In addition,the sensor exhibits good selectivity and anti-interference ability,and can play an important role in the detection of complex samples.The morphology of CNT/GF and Ni were characterized by scanning electron microscopy(SEM),and the electrochemical performance of MIP/CNT/GF were characterized by CV and EIS methods.