Study On Detection Of Tumor Markers By ECL Biosensor Based On Novel Nanocomposite

Cancer,also known as malignant tumor,has become one of the most threatening diseases for human beings.Tumor markers present in human malignant tumor cells can be used as important tools for early detection and diagnosis of cancer.Currently,the biosensor combined with electrochemiluminescence（ECL）technology has a good prospect for accurate detection of tumor markers in clinical samples due to its high sensitivity,low cost and rapid response.In recent years,the development of nanocomposites has brought significant progress for the construction of efficient ECL biosensors.In this work,based on the advantages of carbon-based and metal nanocomposites,ECL immunosensor and aptamer sensors were constructed using prostate-specific antigen（PSA）and mucin-1（MUC1）as detection objects.The main research contents of this paper are as follows:（1）Introducing AgNPs-VB₂ composites as the dual signal quenching of Ce O₂-AuNPs-g-CNQDs hybrids for ultrasensitive"on-off"electrochemiluminescence immunosensing of prostate specific antigenAn ultrasensitive resonance energy transfer based“on-off”switch electrochemiluminescence（ECL）immunosensing strategy was proposed and applied for prostate specific antigen（PSA）detection.In detail,self-enhancing nanohybrids of nano-Ce O₂ and AuNPs decorated graphitic carbon nitride quantum dots（Ce O₂-AuNPs-g-CNQDs）were synthesized,which produced high ECL emission with coreactant K₂S₂O₈ for“switch-on”state.Noticeably,due to the reversible Ce³⁺?Ce⁴⁺reaction,nano-Ce O₂ could serve as highly-efficient coreaction accelerator and induce the decomposition of S₂O₈^2-into SO₄^·-,which endowed the g-CNQDs/K₂S₂O₈ system with enhanced ECL emission.Moreover,AuNPs acted crucial role in promoting the electronic transmission rate and providing sites to immobilize the biomolecules.On the other hand,the AgNPs-VB₂ nanocomposites were used as dual labels to quench the ECL signal of g-CNQDs-K₂S₂O₈ system via ECL-RET,leading to the decreased ECL for“switch-off”state.On the basis of sandwich-typed immunosensing strategy,the developed ECL immunosensing platform exhibited sensitive response to PSA in a linear range of 0.01 pg/m L～50 ng/m L with a low detection limit of 0.0045 pg/m L（S/N=3）.This work provided a promising tool in early clinical diagnostics of prostate cancer.（2）A label-free ECL aptasensor for MUC1 determination based on Cd S QDs@g-C₃N₄and TEOA@AuNPs as bi-coreactants of Ru（bpy）₃²⁺A novel electrochemiluminescence（ECL）aptasensor,using graphite carbonitride（g-C₃N₄）capped Cd S quantum dots（Cd S QDs@g-C₃N₄）and Au nanoparticles decorated triethanolamine（AuNPs@TEOA）as dual coreactants,was proposed for the determination of mucin-1（MUC1）.Higher ECL effificiency was acquired due to the double enhancement contribution of Cd S QDs and TEOA to Ru（bpy）₃²⁺ECL.Additionally,AuNPs@TEOA was also acted as nanocarrier for MUC1 aptamer immobilization.After the ECL aptasensor was incubated in target MUC1,the decreased ECL emission was obtained because of the the poor conductivity of MUC1.The ECL intensity and logarithm of MUC1 concentration showed a good linear correlation in the range of 0.1 pg/m L～1000 ng/m L,and the detection limit was low to 0.05 pg/m L（S/N=3）.Finally,MUC1 spiked into human serum samples was quantified to assess the practicability of the ECL aptasensor,the recoveries ranged from96.83%to 100.17%,indicating that the aptasensor could be used for quantification analysis of MUC1 in human serum samples.（3）The ECL aptasensor based on MoS₂-GQDs nanocomposites and biocatalytic precipitation strategy for the detection of MUC1A novel ECL aptasensor based on MoS₂-graphene quantum dots（GQDs）nanocomposite modified electrode was developed for sensitive MUC1 detection using horseradish peroxidase（HRP）catalyzed biocatalytic precipitation（BCP）for signal quenching.The nanocomposite was modified onto the GCE surface and employed as the immobilization matrix,then the complementary strand（c DNA）of MUC1 aptamer was connected to GODs by chemical reaction.Meanwhile,HRP functionalized gold nanoparticles（AuNPs）labeled aptamer（aptamer-AuNPs-HRP）was designed as the signal probe for the aptasensor and immobilized onto the GCE through aptamer-c DNA hybridization.In the presence of H₂O₂,HRP modified on the electrode can catalyze and oxidize 4-chloro-1-naphthol and nonconductive substance precipitated on the surface of the electrode,which caused the obvious decrease of ECL signal.In the presence of MUC1,the signal probe would capture MUC1 to form conjugation,released from the electrode accompanying decrease of HRP and increase of ECL intensity.The results showed that there was a good linear relationship between ECL intensity and the logarithm of MUC1concentration in the range of 0.5 pg/m L～10 ng/m L,and the detection limit was 0.3 pg/m L（S/N=3）.