Construction And Application Of Electrochemical Immunosensor Based On Cobalt-Organic Metal Framework Materials

Acute myocardial infarction（AMI）is a sudden cardiovascular disease.Millions of people died of AMI worldwide in the last year alone.Cardiac troponin I（cTnI）is a specific diagnostic criterion for acute myocardial infarction.When the myocardium is damaged,cTnI will be rapidly released into the blood.Through the specific binding of antigen-antibody and the advantages of electrochemical analysis,the high specificity and sensitivity of electrochemical immunosensor can accurately detect cTnI to achieve early diagnosis and detection of AMI.With the development of metal-organic framework materials（MOF）,cobalt（Co）-based metal-organic framework materials have attracted great interest due to their potential application value in many fields due to their unique electrochemical properties.Among them,the research and application of porous organic hybrid unique structure and properties of MOF materials in the field of biology and medicine has become a hot spot in recent years.In this work,ultra-thin two-dimensional cobalt-tetrakis（4-carboxyphenyl）porphyrin（2D-Co-TCPP）and core-shell cubic cobalt zeolite imidazole framework-67 layered double hydroxide supported gold nanoparticles（Au/Co-LDH@ZIF-67）were prepared.Based on the good electrochemical properties of the material itself,two electrochemical immunosensors with simple preparation and high sensitivity were constructed for the detection of cardiac disease marker cTnI,which enriched the detection methods of cTnI.The main research work is as follows:1.An ultra-thin two-dimensional cobalt-based tetrakis（4-carboxyphenyl）porphyrin（2D-Co-TCPP）was combined with gold nanoparticles（Au NP）to form Au/2D-Co-TCPP as a substrate material to construct a conductive label-free immunosensor for the detection of cardiac troponin I（cTnI）.Compared with its corresponding 3D-Co-TCPP,the2D-Co-TCPP synthesized by one-pot method has a larger effective specific surface area and can link more capture antibodies（Ab₁）.Greatly change the conductivity of the sensor under the same concentration conditions and improve the sensitivity of the sensor.An easy-to-build,high-sensitivity,conductivity-type label-free immunosensor for the detection of cTnI was obtained.Under the optimal conditions,the detection range of cTnI was 100fg/m L-100 ng/m L,and the detection limit was 8.40 fg/m L.Through the application test in the actual sample detection,the feasibility of the label-free electrochemical immunosensor with fast detection speed,high construction efficiency and convenient detection method was verified,and satisfactory results were obtained.2.A sandwich electrochemical immunosensor for the detection of cTnI was constructed by using Pd Ag Fe asymmetric bowl-like mesoporous nanospheres（Pd Ag Fe ABMS）as signal amplification marker and core-shell cubic Au/Co-LDH@ZIF-67 as substrate material.Pd Ag Fe ABMS prepared by dual-template directional anisotropic island growth method has abundant mesoporous channels,which can accelerate molecular mass transfer in solution.In particular,the asymmetric bowl junction exposes more active sites,improves the utilization of atoms,and provides a stable high current response signal.The synergistic effect between Pd Ag Fe increased the activation energy of the catalytic reaction and further amplified the current signal.In addition,the sensing interface constructed by Au/Co-LDH@ZIF-67 not only exhibits a high electron transfer rate,but also can capture more bioactive molecules.Based on the above strategy,a sandwich electrochemical immunosensor with high sensitivity and good accuracy was obtained for the sensitive detection of cTnI.Under the optimal experimental conditions,the current response range of the constructed signal amplification sandwich electrochemical immunosensor to cTnI was 10 fg/m L-100 ng/m L,and the detection limit was 4.47 fg/m L（S/N=3）.The feasibility of the sandwich electrochemical immunosensor with good selectivity,high sensitivity and good reproducibility was verified by the application test in the actual sample detection,and satisfactory results were obtained.