Construction Of Polymer Film And Metal Organic Framework Electrochemical Sensor And Its Detection Of Biomarkers

Electrochemical sensors not only have the advantages of convenience,sensitivity and good selectivity in analysis and detection,but also are suitable for on-line analysis,so as to be a common method of analysis and detection.In recent decades,electrochemical sensor technology has been widely used in some fields,including clinical detection,environmental protection,and pharmaceutical analysis.As one of the traditional electrochemical modified material,organic polymer membrane is widely considered as an excellent substitute for sensing applications due to its good stability.In addition,with the emergence of various nano materials showing superior performance,their development influence in the field of electrochemical sensor is also increasing.Graphene,carbon nanotubes and metal-organic frameworks can effectively increase the specific surface area of the electrode to a certain extent,accelerate the electrode catalytic reaction,so as to play an excellent electrocatalytic activity.Therefore,in this thesis,functionalized electrochemical sensors based on polymer film nanomaterials were constrected for the analysis and detection of related biomarkers.This paper summarizes the main research content into the following three aspects:（1）A simple and sensitive electrochemical sensor with A-PCA film modified electrode for the determination of metanephrineElectrochemical acid pretreatment was performed on the surface of the bare glass carbon electrode.Acidification can increase the background current and oxygen content,forming a porous,oxidized and multi-layer activated surface to promote electron transfer.Based on the constructed acidification electrode（AGCE）,A-PCA/GCE was prepared by electrodeposition of caffeic acid on its surface.Scanning electron microscopy（SEM）and electrochemical techniques（cyclic voltammetry,linear scanning voltammetry）were used to characterize the surface morphology of the modified electrodes.The electrochemical behavior of metanephrine was investigated by using the modified electrodes.The results indicate that A-PCA/GCE has the large specific surface area,which can promote the electron transfer on the surface of electrode and effectively catalyze the electrochemical transformation of metanephrine.At the same time,we have investigated the deposition time of caffeic acid,the pH of buffer solution and scan rate.Under the best optimized experimental parameters,the linear relationship between the oxidation peak current of metanephrine and its concentration in the range of 0.5～40.0μM was good,the linear correlation coefficient（r）was 0.9926 and the detection limit（LOD,S/N=3）was 0.17μM.The modified electrode can be successfully used for the detection of metanephrine in human serum samples.（2）An UiO-66/P-L-histidine composite film fabricated by electropolymerization and electrodeposition for sensing cancer biomarker（4-nitroquinoline N-oxide）In this experiment,the L-histidine and zirconium metal-organic framework（UiO-66）were modified on the surface of glassy carbon electrode by the combination of electropolymerization and electrodeposition to prepare the UiO-66 and L-histidine modified electrode（UiO-66/P-L-his/GCE）.Techiques such as SEM,TEM,EDS,FTIR,CV and DPV were used to characterize the modified electrode.The results show that UiO-66/P-L-his/GCE has excellent electrocatalytic performance for 4-nitroquinoline N-xide.At the same time,the polymerization time of L-histidine,deposition time of UiO-66,buffer solution pH and scanning rate were also investigated and optimized.With the optimized parameters,the linear relationship between the reduction peak current of 4-nitroquinoline N-xide and its concentration in the range of 0.2 to 50.0μM was good,the linear correlation coefficient r was 0.9981,and the LOD was 66.7 nM（S/N=3）.In partical applications,the modified electrode can be successfully applied to the determination of 4-nitroquinoline N-xide in human serum with satisfactory results.（3）Preparation of poly L-lysine and electrodeposition of Al metal-organic framework modified electrochemical sensors and electrochemical behavior of xanthineIn the experiment,the synthesized aluminum metal-organic framework nano-material（NH₂-MIL-53）and the organic substance L-lysine were modified on the surface of the glassy carbon electrode by electropolymerization and electrodeposition to obtain the modified electrode（NH₂-MIL-53/P-L-lys/GCE）.Compared with the bare electrode,the modified electrode improved the oxidation peak current response of xanthine.Because P-L-lys has superior electrocatalytic activity,combining with the large specific surface area of NH₂-MIL-53.Besides,the modified electrode can play an excellent synergistic role in promoting electron transfer and improving electrochemical behavior of xanthine.In addition,SEM,TEM,EDS,FTIR,CV and LSV were used to characterize the modified electrode,and the electrochemical behavior of the xanthine on the modified electrode was studied.As a result,with the optimized parameters,NH₂-MIL-53/P-L-lys/GCE showed a good response to xanthine,and the linear range of detection was 3.0 to 25.0μM,r was 0.9940,and LOD was0.37μM（S/N=3）.The determination of xanthine in serum can be successfully performed on this modified electrode with satisfactory recovery rate.