| Objective:As a tumor marker,Carbohydrate Antigen 125 is a good indicator effect on such cancers like ovarian cancer,pancreatic cancer,so the rapid,sensitive and low-cost detection of CA125 is crucial for early screening,diagnosis and prognosis of related cancer.Electrochemiluminescence?ECL?has the characteristics of sensitivity,small background effect and simple operation compared with traditional analytical methods.With the continuous emergence of new materials and new systems in recent years,ECL has been developing rapidly and is widely used in the detection of proteins,nucleic acids,viruses and other substances.Graphite carbon nitride?g-C3N4?and quantum dots?QDs?,as novel semiconductor nanomaterials,have great prospects in the field of ECL sensing due to their uniquely physical and chemical properties.This study on the analysis of the current commonly used system and developing trend of ECL,is the first reporter near infrared cadmium telluride/cadmium sulfide quantum dots?NIR CdTe/CdS QDs?has stronger quenching effect on fluorescent and ECL of g-C3N4.ECL immunosensor has been constructed on the basis of previous phenomenon,achieving the sensitive detection of CA125 in serum.It provides a new method for the sensitive detection and sensing analysis of CA125 and other biological macromolecules.Methods:?1?CdTe/CdS QDs that can produce near-infrared fluorescence and ECL were prepared.Meanwhile,Graphite carbon nitride nanosheets?g-C3N4 NS?and Au-g-C3N4 NHs with high biocompatibility and electrochemical stability were prepared by ultrasonic stripping method.The prepared materials were characterized by TEM,fluorescence spectrum and UV-visible absorption spectrum,and The ECL process of the prepared material on glassy carbon electrode was analyzed.?2?On the basis of previous studies,the"signal-off"ECL immunosensor of CA125 was constructed on the glassy carbon electrode modified with Au-g-C3N4 NHs and loaded with a primary antibody.SiO2 was used as the signal amplifier to load a large number of CdTe/CdS QDs labeled secondary antibody.The materials were characterized by TEM,fluorescence and UV-visible spectra.The layers of the sensor were characterized by electrochemistry and the ECL process of the sensor was analyzed.On the basis of the optimization of the pH value,the concentration of co-reactant and the incubation time,the sensor of linear range,detection limit and stability of the sensor were verified and used for the actual sample detection.Results:?1?It was found that CdTe/CdS QDs had a quenching effect on fluorescence and ECL of g-C3N4 NS,and the possible mechanism was energy resonance transfer.Further study found that by adjusting the overpotential can make CdTe/CdS QDs with quenching effect on Au-g-C3N4 NHs blue-ray ECL also launch near-infrared light of ECL,namely Au-g-C3N4 NHs launch light wavelength of 460 nm blue ECL quenching,and as a quenching effect of CdTe/CdS QDs also launch a wavelength of 660 nm red ECL,but it is not stable.?2?The constructed sensor in CA125 concentration range0.0001 to 10 U/mL has a good linear relationship,the regression equation for?IECL=1213.5lgCCA125+6078.8 R2=0.9949.The detection limit of the sensor was 3.4×10-5U/mL,and the recovery was 95.38%to 104.7%,The constructed sensor is good stability and strong specificity.The recovery relative standard deviations?RSD?were less than5.43%,and this sensor has been used in actual analysis of CA125 in serum samples successfully.The results are in good agreement with commercial methods.Conclusions:It's the first report that NIR CdTe/CdS QDs is efficient quenching effect on fluorescent and ECL of g-C3N4,and the"signal-off"ECL immunosensor of CA125was constructed on the basis of previous phenomenon and successfully used in actual analysis of CA125 in serum samples.This study provides technical support for the screening,diagnosis and prognosis of ovarian cancer and related cancers,and also may provide new ideas for future multi-indicator,high through-put biosensors. |
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