An Electrochemical Immunosensor Based On CMK-3@AuNPs And PdPt-poly(Methylene Blue) For Sensitive Detection Of CTnⅠ

Objective:Cardiac troponin I（cTnⅠ）is considered as gold standard of AMI diagnosis.The traditional cTnⅠ detection is limited by long experimental period,low sensitivity or sophisticated experimental operation.Herein,in present study,a sensitive,simple and economical sandwich-type electrochemical immunosensor was proposed for cTnⅠ detection.Methods:1.Preparation of CMK-3 nanocomposite and AuNPs.Stepwise assembly modified electrodes:CMK-3,AuNPs and primary antibodies（Ab₁）were modified onto the gold electrode（GE）surface gradually.2.Preparation of novel redox nanoprobe PdPt-poly（methylene blue）（PdPt-PMB）nanoparticles by one-pot method to bind with detection antibodies（Ab₂）.In the existence of cTnⅠ,a sandwich-type immunosensor was composed.3.Under the optimized experimental conditions,differential pulse voltammetry（DPV）is used to detect cTnⅠ with different gradients of concentration.Evaluation of the performance of the immunosensor:such as calibration curve,limit of detection,selectivity,reproducibility,stability and potential in clinical application.Results:1.The CMK-3 nanocomposite and AuNPs were successfully synthesized.The morphologies of CMK-3 were characterized by SEM,the morphologies and size of AuNPs were characterized by TEM.The potential of CMK-3 and AuNPs were detected by zeta-potential methods,to demonstrate the electrostatic attraction between CMK-3 and AuNPs.The stepwise modification of electrode was investigated by CV and EIS,the results demonstrated the successful self-assembly of electrode through layer-by-layer.2.The PdPt-PMB composites were successfully synthesized.TEM and SEM were used to characterized the morphologies of the prepared PdPt-PMB,which exhibited rod-like nanostructure with rough surface and excellent homogeneous morphology.EDS and XPS were used to demonstrated that the PdPt-PMB composites were successfully synthesized further.The results are satisfactory.3.The constructed immunosensor displayed a good linear relationship extends from 0.001 to 10 ng m L^-1 with a limit of 0.3 pg m L^-1 under the optimal experimental conditions.The developed method displayed excellent performance,satisfactory specificity,good reproducibility and stability.Conclusion:The present study proposed a novel amplification strategy to construct an immunosensor based on CMK-3/AuNPs and PdPt-PMB for sensitive and specific detection of cTnⅠ concentration.CMK-3/AuNPs combination not only guaranteed enough specific surface area,but also excellent conductivity;PdPt-PMB nanocomposites as a new type of redox nanoprobe,which further provided strong redox current and enhanced H₂O₂catalytic activity.Based on the above advantages of nanomaterials,the proposed immunosensor exhibited excellent sensitivity with a broad detection range and low detection limit.Additionally,this immunosensor provided perfect selectivity and stability,which can be applied to distinguish cTnⅠ from other interfering substances and monitor the low concentration of cTnⅠ in serum samples.Thus,this immunosensor exhibited a good analytical performance,indicating that the developed immunosensor could serve as a potential technique to detect other target protein.