Application Research Of Electrochemistry In The Diagnosis And Treatment Of Alzheimer’s Disease

Alzheimer’s disease is a severe neurodegenerative disease.The overproduction and misfolding ofβ-amyloid peptide are considered to be the main pathogenic mechanism of Alzheimer’s disease.β-amyloid peptide will aggregate to form neurotoxic oligomers and fibrils,leading to symptoms such as senile plaques and neuronal fiber tangles.Soluble Aβoligomer is considered to be the key element to amyloidosis and cytotoxicity.Therefore,it is crucial to develop a method for detecting Aβoligomer with high sensitivity and selectivity,so is monitoring the degradation process of Aβoligomer.This paper takes Aβoligomer,which is the disease marker of Alzheimer’s disease,as the main research object.Electrochemical method was applied to quantitatively detecting Aβoligomer.Signal amplification based on peptide self-assembly was introduced to enhance the sensor’s performance.Poly（vinylcaprolactam）complex with Fullerene C₆₀was used to generate reactive oxygen radicals driven by light to degradate Aβoligomers.The degradation process was monitored by electrochemical method.Specific research contents are as follows:1.First,the quantitative detection of Aβoligomer was achieved by constructing an electrochemical sandwich immunosensor with peptide CP₄-Pr P（95-110）as the capture sequence and peptide Fc-Pr P（95-110）as the recognition sequence.Potassium ferricyanide probe was used to characterize the layer-by-layer assembly process of the sensor.Then the capture sequence was replaced with peptide 937 and the Aβoligomer modification step was eliminated to prove the immune response between peptide CP₄-Pr P（95-110）,Aβoligomer and peptide Fc-Pr P（95-110）.Then the specificity of the sensor was measured by detecting the electrochemical signals of the assembly process and detecting different forms of Aβ.Cyclic voltammetry curves at different scan rates were used to study the electron transfer mechanism of the sensor,and stability of the sensor was observed through continuous scanning and continuous detection.Finally,Aβoligomer in a certain concentration range was detected to obtain the detection limit of the sensor.2.Then,a amphiphilic self-assembling peptide C₁₆-GGG-Pr P（95-110）-Fc with dual functions of electrochemical activity and self-assembly ability was designed.It was used to construct an alternative recognition sequence.We characterize the self-assembly properties of peptides by means of circular dichroism（CD）,atomic force microscopy（AFM）,transmission electron microscopy（TEM）.Otassium ferricyanide probe was then used to characterize the immune reaction between peptide C₁₆-GGG-Pr P（95-110）-Fc fibril,Aβoligomer and the capture sequence CP₄-Pr P（95-110）.After optimizing the experimental conditions of the self-assembly time,self-assembly concentration,and self-assembly condition of peptide C₁₆-GGG-Pr P（95-110）-Fc,different concentrations of Aβoligomer were detected to obtain performance of the sensor with a signal amplification based on peptide self-assembly.Continuous scanning and detection in a row were used again to characterize the electron transfer mechanism and electrochemical stability of the nanofibril modified electrode.3.Finally,lipoic acid was self-assembled on the electrode to form monolayer,Aβmonomers were binding to the electrode through the reaction between lipoic acid and Aβ.Then Aβmonomers were used to induce the formation of Aβoligomers.Queous solution of fullerene was prepared by PVP-mediated method,and the water-soluble fullerene was stimulated to generate active oxygen radicals under the light to degrade the Aβoligomers modified on the electrode.The process of aggregation and degradation of Aβon electrode were characterized by potassium ferricyanide probe.During the process of aggregation and degradation,the 10th amino acid of Aβwas used to monitor the aggregation and degradation process of Aβ.