Fabrication Of Electrochemical Sensors Based On Porous Carbon Materials Derived From MOF And Their Application For β-amyloid Protein Detection

Alzheimer’s disease（AD）is an irreversible neurodegenerative disease with a high incidence in the elderly.With the increasing aging trend of the population,Alzheimer’s disease has become the third leading cause of death after cancer and cardiovascular and cerebrovascular diseases,bringing a heavy burden to society and families.The pathogenesis of the disease has been studied,and it has been found that patients have A large number of age spots in the brain,the main component of which is beta-amyloid protein（Aβ）.Aβaggregates to form Aβoligomers（AβOs）which are toxic to cells.The severity of the disease was closely related to the amount of AβO in the cerebrospinal fluid,also known as A disease marker for AD.Therefore,the development of simple,economical and efficient quantitative detection of AβO is of great importance for the effective early diagnosis of AD patients.In this paper,two electrochemical Apt.sensors with excellent performance were developed for AβO detection,which can accurately detect AβO in human serum.The construction strategy can also provide reference for the detection of other disease markers.The main contents are as follows:（1）A biological aptamer sensor was constructed based on Apt./MB/ZC-T stimulus response and MB signal amplification strategy for quantitative detection of AβO.Firstly,ZIF-8was synthesized by hydrothermal method,and then carbonized by high temperature at 500℃,700℃and 800℃to obtain nano-porous carbon material（ZC-T）,which was used as nanovessel for loading electroactive methylene blue（MB）to form MB/ZC-T.The ZC-T was characterized by SEM,TEM and BET,and optimized by experiment to obtain the ZC-T with large pore size,pore volume and maximum load.Then Apt.can be deposited on the surface of MB/ZC-T byπ-πstacking to form Apt./MB/ZC-T,and MB can be encapsulated inside ZC-T to form stimulus response material.When AβO is added,Apt.reacts prefertively with AβO to form AβO-Apt.complex,which leaves the surface of the material and MB is released into the solution.Secondly,CP/Au NPs/GCE is formed by electrodeposition of Au NPs on the surface of GCE and then fixation of aptamer（MB）that can capture MB released into solution by Apt./MB/ZC-T.The deposition of Au NPs increases the conductivity of the electrode and promotes electron transport.Secondly,Au NPs increases the area of the substrate,which can fix more CP,so that the MB to be detected can be enriched and accumulated on the electrode surface to achieve the purpose of signal amplification and improve the sensitivity of the sensor.Under optimized experimental conditions,the linear range of the sensor is 50 f M-10 n M,and the detection limit is 1.58f M.（2）A two-mode aptamer sensor was developed based on electrochemical and fluorescence detection methods.UIO-66-NH₂ was synthesized by hydrothermal method for nanocontainer and loaded MB.The synthesis of UIO-66-NH₂ and MB/UIO-66-NH₂ was verified by SEM,EDS,FT-IR and other characterization methods.aptamer（Apt.（FAM））coated Fe₃O₄ with fluorescent groups was used as biological gating（Apt.（FAM）-Fe₃O₄）.The synthesis of Apt.（FAM）-Fe₃O₄ was verified by SEM,XRD and EDS characterization methods.The successful assembly of Apt.（FAM）-Fe₃O₄/MB/UIO-66-NH₂ was verified by EDS.The modification method of detecting electrode is shown in the previous chapter.When AβO is introduced,Apt.（FAM）prefertively binds to AβO to form AβO-Apt.（FAM）/Fe₃O₄ complex,which is detached from the surface of UIO-66-NH₂ and MB is released for electrochemical detection.The AβO-Apt.（FAM）/Fe₃O₄ dissociated in solution can be rapidly separated by magnetic separation.When Na OH was added and Apt.（FAM）left the surface of Fe₃O₄,the fluorescence groups were restored for fluorescence detection.Under optimized experimental conditions,A wide detection range（10 f M～10μM）and a low detection limit（3.4 f M）were obtained for AβO detection.