Electrochemical Sensor Based On Functional Nanomaterials And Its Application In Detection Of Disease Markers

Electrochemical sensors are the combination of electrochemical analysis and sensor technology,which has the advantages of fast response,low cost,low consumption,high sensitivity,good selectivity and suitable for online analysis.It has been widely used in clinical detection,medicine analysis,environmental monitoring and other research fields.The superior performance of nanomaterials catalyzes the rapid development of modified electrochemical sensors.Nanomaterials such as graphene,carbon nanotubes,metal nanoparticles,and functionalized derivatives have greatly improved the electrochemically analytical performance of electrochemical sensors due to their excellent catalytic properties and adsorptive properties.Constructing a new type of functionalized nanomaterial-modified electrochemical sensor to exert superior electrocatalytic activity has become a research trend and hotspot in electroanalytical chemistry.Therefore,in this dissertation,several electrochemical sensors modified with different functionalized nanomaterials were constructed and applied to the specific and sensitive analysis of related disease markers.The main research content of this paper can be summarized as the following four aspects:（1）Electrochemical anodizing pretreatment of glassy carbon electrode and its electrochemical behavior to 3-nitrotyrosineA simple,environmentally friendly and sensitive activated glassy carbon electrode（activated GCE）was prepared based on an electrochemical anode pretreated glassy carbon electrode.In addition,an anionic surfactant（sodium dodecyl sulfate,SDS）was added to a 0.1 M HNO₃ solution.A small amount of SDS surfactant was adsorbed on the activated GCE surface,which promoted the exchange of electrons and significantly increased the surface area of the electrode.Increasing the electrode surface hydrophobic surface,which enhances the electrochemical response to 3-nitrotyrosine.Studies have shown that activated GCE is superior to the electrochemical catalysis of 3-nitrotyrosine.The introduction of SDS surfactant can further enhance the reduction peak current of 3-nitrotyrosine and accelerate the electron transfer efficiency.Under optimized conditions,the linear relationship between the reduction peak current of 3-nitrotyrosine and its concentration in the range of 0.05³0.0μM was good,and the linear correlation coefficient（r）was 0.9964.（LOD,S/N=3）is 17.0μM.The method can be successfully used for the detection of 3-nitrotyrosine in human serum samples.（2）Preparation of GO-ε-MnO₂ modified activated glassy carbon electrode and its electrochemical study on tyrosineIn the experiment,the graphene oxide-ε-manganese dioxide composite dispersion（GO-ε-MnO₂,dispersed in 0.05%chitosan solution）was modified on the surface of an electrochemically activated glassy carbon electrode by a drop-coating method.A graphene oxide-ε-manganese dioxide modified electrochemically activated glassy carbon electrode（GO-ε-MnO₂/chitosan/activated GCE）was developed.The surface morphology of the modified electrode was characterized by scanning electron microscopy（SEM）,X-ray diffraction,and electrochemical techniques（cyclic voltammetry,differential pulse stripping voltammetry,linear sweep voltammetry,timed coulomb,etc.）.The electrochemical behavior of tyrosine at the modified electrode.It was found that GO-ε-MnO₂/chitosan/activated GCE has excellent electrochemical catalytic performance for tyrosine.The conditions of electrochemical activation,concentration of nanomaterials,pH of buffer solution,and scanning rate were optimized.Under the optimized conditions,the tyrosine oxidation peak current showed a good linear relationship with its concentration in the range of 0.02 to 20.0μM,r was-0.9985,and the LOD was 8.3 nM（S/N=3）.Modified electrodes can be successfully used for the analysis of tyrosine in serum filters and milk samples with satisfactory results.（3）Preparation of functionalized nanomaterial molecularly imprinted electrochemical sensors and investigation and application of electrochemical behavior of 3-nitrotyrosineThe nanomaterials of multi-wall carbon coupled graphene oxide nanoribbons（MWCNT@GONRs）was modified on the surface of bare glassy carbon electrode by drop coating method.After activation of this electrode,activated multi-walled carboncoupled graphene oxide nanoribbons were modified.After the electrode（AMWCNT@GONRs/GC-E）,the modified electrode was placed in a mixed solution containing a pyrrole-functional monomer,a chloroauric acid,and a 3-nitrotyrosine template molecule to conduct electropolymerization to prepare a molecularly imprinted membrane.Nanomaterial-modified Molecularly imprinted electrodes（AuNPs/MIP/AMWCNT@GONRs/GCE）.The electrochemical behavior of 3-nitrotyrosine was analyzed by SEM and electrochemical methods.As a result,it was found that AuNPs/MIP/AMW-CNT@GONRs/GCE had a good response to 3-nitrotyrosine,and the selectivity,reproducibility,and stability of the analysis were excellent.The linear range of detection was 0.2 to 50.0μM,r was-0.9967,and LOD was50.0 nM（S/N=3）.The determination of 3-nitrotyrosine in serum and urine can be successfully performed on this nanomaterial-modified molecularly imprinted electrode,and the recovery rate is satisfactory.（4）Preparation of poly-m-aminobenzenesulfonic acid modified electrode and its electrochemical behavior and application to normetanephrineIn the experiment,m-aminobenzene sulfonic acid was polymerized on the surface of bare glassy carbon electrode by pulse potential method,and a simple and sensitive poly-amino-benzenesulfonic acid film modified electrode（p-m-ABAS/GCE）was constructed.The surface morphology of the modified electrode was characterized by SEM and electrochemical techniques（cyclic voltammetry,differential pulse voltammetry,etc.）,and the electrochemical behavior of normetanephrine was investigated using this electrode.The results showed that p-m-ABAS/GCE has many active sites and large specific surface area.The electrochemical catalytic performance of p-m-ABAS/GCE is good.The optimal conditions for the polymerization time of m-aminobenzenesulfonic acid,the buffer solution pH,the type of buffer solution,and the scanning rate were investigated.Under optimized conditions,the peak current of normetanephrine showed a good linear relationship with its concentration in the range of 0.5³0.0μM,r was-0.9985,LOD was 0.17μM（S/N=3）.Modified electrodes can be successfully used for the determination of normetanephrine in serum samples.