Construction And Application Of Electrochemical Sensor Based On Signal Cycle Amplification Strategy

Acute myocardial infarction is a common cardiovascular disease that results in irreversible tissue necrosis due to myocardial hypoxia and has a high clinical mortality rate.Rapid diagnosis and treatment can effectively reduce the fatality rate and improve the cure rate of patients.Cardiac troponin I（c Tn I）is a special regulatory protein in myocardial tissue that inhibits the binding of myosin to actin.In the early stage of acute myocardial infarction,the level of c Tn I increases rapidly and fluctuates greatly.In addition,c Tn I is highly specific to myocardial cells.Therefore,c Tn I can be used as a sensitive and specific disease marker for the diagnosis of cardiomyocyte injury,and has gradually become an important biochemical indicator for determining cardiomyocyte injury in patients with acute myocardial infarction in vivo.In terms of quantitative detection,the use of electrochemical immunosensors to determine the concentration of c Tn I is an important way.Sensitivity is one of the key factors to evaluate the excellent performance of electrochemical immunosensors.Therefore,in order to improve the sensitivity of the immunosensor and meet the higher requirements of practical applications,this study designed electrochemical immunosensor using efficient catalytic cycle amplification strategy,which leads to the sensitive detection of c Tn I.The main research content is as follows:1.Using Cu₂O/Cu O@CeO₂-Pd as signal amplification platform,a label free electrochemical immunosensor with signal cycle amplification strategy was constructed for sensitive detection of c Tn I.Firstly,the coupled Cu²⁺/Cu⁺and Ce⁴⁺/Ce³⁺in Cu₂O/Cu O@CeO₂realized the bidirectional cycle of redox reaction,and the synergistic effect of Ce⁴⁺and Cu⁺accelerated the electron transfer rate on the electrode surface and amplified the intensity of the response signal.Rough and prickly Cu₂O/Cu O@CeO₂ had a larger specific surface area,which can expose more catalytic active sites and load more Pd nanoparticles（Pd NPs）.The presenced of a large number of Pd NPs not only further improves the conductivity of the amino functionalized Cu₂O/Cu O@CeO₂,but also more effectively guarantees the effective connection of the antibody（Ab）,improving the sensitivity of the electrochemical immunosensor.Under the optimal experimental conditions,the linear range of the constructed electrochemical immunosensor detection was 100 fg/m L-100 ng/m L,and the detection limit was 15.85 fg/m L.The signal cycling amplification strategy effectively enhances the output response signal strength,and exhibits a wide detection range and high sensitivity in detecting c Tn I.2.Based on electroplated Au（E-Au）as substrate material and Cu Fe₂O₄-Pd as secondary antibody marker,an electrochemical immunosensor with signal amplification strategy was constructed for sensitive detection of c Tn I.Firstly,Cu Fe₂O₄ with coupled variable valence metal elements exhibited favorable catalytic performance through bidirectional cycling of Fe²⁺/Fe³⁺and Cu⁺/Cu²⁺redox pairs.Compared with the previous research work,this work realized the bidirectional redox strategy using a single nanomaterial,and introduced the functional nanomaterial of"all-in-one"into sensing analysis.More importantly,Cu⁺,as an intermediate product of the catalytic reaction,promotes the regeneration of Fe²⁺and ensures the continuous recycle of redox pairs.Pd nanoparticles（Pd NPs）loaded on the surface of amino-functionalized Cu Fe₂O₄ were served as electrochemical mediators to capture labeled antibodies（Ab₂）,and also as co-catalysts of Cu Fe₂O₄ to further enhance the catalytic efficiency,improving the sensitivity of the electrochemical immunosensor.In addition,E-Au with excellent conductivity accelerated the electron transfer at the electrode interface and improved the sensitivity of the electrochemical immunosensor.Through the effective coordination of Cu Fe₂O₄-Pd and E-Au,the designed electrochemical immunosensor showed excellent analytical performance for the detection of c Tn I.Under the optimal experimental conditions,the linear range was 10 fg/m L-100 ng/m L,and the detection limit was as low as 1.03 fg/m L.The electrochemical immunosensor constructed by catalytic cyclic amplification strategy provides a new idea for sensitive detection of markers and has great potential for application in immunoassays.