Preparation Of Cr/N Doped Jasmine Carbon By Mechanical Ball Milling And Fe-bridged GDY/MOFs Composites And Electrochemical Detection Of Human Disease Makers

Human bioactive small molecules dopamine（DA）and uric acid（UA）are signal molecules for Parkinson’s disease,Alzheimer’s disease,hyperuricemia and so on.The Prostate specific antigen（PSA）is a signal protein of human prostate cancer.Abnormalities in the levels of these signals occur when a person has a disease.Therefore,the detection of these disease markers is helpful in the early diagnosis and rehabilitation monitoring of these diseases.In this work,different types of electrochemical sensors were designed to detect the DA/UA and PSA.Summary of the specific studies conducted are as follows:（1）The integration of Cr/dopamine doped Jasmine porous carbon material（Cr/N-JFC）was applied to synthesize Cr/N-JFC/Nafion/GCE sensor for simultaneous detection of DA and UA through modified electrodes.The jasmine flower residues were doped with different kinds of transition metals Cr,Fe,Co and dopamine by mechanical ball milling pretreatment and high temperature carbonization,and the influence of different kinds of transition metal and amount of doped-dopamine on DA/UA detection was investigated.The crystal morphology,specific surface area and pore structure of the material were analyzed by scanning electron microscope（SEM）,transmission electron microscope（TEM）,X-ray diffraction（PXRD）,X-ray photoelectron spectroscopy（XPS）,N₂ isothermal desorption and other characterization methods.Similarly,the electrochemical performance of the material was analyzed by electrochemical impedance spectroscopy（EIS）and cyclic voltammetry（CV）.The characterization results showed that through mechanical ball milling technique,jasmine petals powder and dopamine were evenly mixed on one hand and on other hand,the oxygen-rich functional groups of jasmine petals dopamine formed a cross-linking network,which inhibited the reduction of dopamine.By further ball milling,chromium ions were uniformly anchored into the cross-linking network formed by jasmine petals and dopamine via dopamine coordination.After high temperature carbonization,crystal lattice interchanges of different complexes of Cr occurred,and multi-grain interface was formed within the graphitized carbon skeleton.On one hand,the multi-grain interface structure of Cr-O/N anchored into the carbon skeleton can provide a large number of catalytic sites,while on other hand,the interface formed between different valence chromium metals and N,O and C promoted the electron mobility.Moreover,the introduction of N-source dopamine can promote the production of a large number of micropores in carbon materials,which favored adsorption of DA/UA.The Cr/N-JFC/Nafion/GCE sensor was constructed by chemically modifying the Cr/N-JFC material,and DA and UA were detected under the optimal electrolyte p H（6.0）and adsorption time（20.0min）of the measured substance.The linear range was 0.05～4.00μM,and the LOD detection limit was 10.65 n M and 17.54 n M,respectively.The prepared sensor exhibited good anti-interference ability,reusability and high stability,and the standard recovery of DA and UA in actual human serum samples was between 97.00%and 104.00%.（2）The prepared Fe-GDY in which Fe ions were uniformly dispersed on the graphdiyne（GDY）was combined with NMIL88（Fe）by in situ Fe bridge strategy to prepare Fe-GDY_X@NMIL（Fe）composite material.The probe Fc-KHSSKLQK（Fc-peptide）with high electrochemical response signal and tight connection with Fe-GDY_X@NMIL（Fe）was obtained by modifying HSSKLQ peptides（adding glutamate（K）containing-NH₂ in both side of the chain of the C-end and N-end,modifying ferrocene groups at the N-end of the peptide）which can be cut by PSA specifically.Then,a peptide sensor was prepared by immobilizing Fc-peptide probe onto Fe-GDY_X@NMIL（Fe）which grafted glutaraldehyde.The detection of PSA was realized by the specific hydrolysis of peptides fixed on the composite material by PSA.Scanning electron microscope（SEM）,transmission electron microscope（TEM）,X-ray diffraction（PXRD）,N₂ isothermal desorption,infrared spectroscopy（FT-IR）,thermogravimetric analysis（TGA）,electrochemical alternating impedance（EIS）and cyclic voltammetry（CV）were used to analyze the microstructure,crystal structure,functional group types,thermal stability and electrochemical performance of the materials.The results show that the Fe atoms on Fe-GDY can be used as the anchor points for the growth of NH₂-MIL-88B（Fe）to realize the growth of MOFs on Fe-GDY.The formed Fe-GDY conductive interface can not only construct a highly conductive network in the Fe-GDY_X@NMIL（Fe）composite material to realize the rapid conduction of electrical signals,but also enable the growth of NH₂-MIL-88B（Fe）in the limited domain of Fe-GDY interface to form defective metal clusters with high catalytic activity.The electrochemical detection of high signal strength can be achieved by improving the redox ability of Fc-peptide.The modified composite possessed good hydrophilicity,which was beneficial to avoid non-specific adsorption of proteins interfered by impurities.The synthesis process of the peptide sensor was analyzed by Square Wave Voltammetry（SWV）and results showed that the optimum amount of Fe-GDY in the composite was 40%.The incubation time of the Fc-peptide probe and the hydrolysis time of PSA were 80 min and 30 min.Finally,PSA was detected under optimal conditions.The detection range was1.0 pg/m L～50.0 ng/m L,and the detection limit was 0.37 pg/m L.The cost effective metal sensor exhibited high sensitivity,good stability and repeatability for PSA detection,and has been successfully applied for the detection of actual human serum samples.