| Thyroid disease is the second largest endocrine disease,in which differentiated thyroid cancer is the most common thyroid malignancy,accounting for 1% of all human cancer.Thyroglobulin is a glycoprotein precursor secreted only by thyroid follicular cells,and is often used as a sensitive and specific serum marker for thyroid cancer recurrence or metastasis after thyroidectomy in patients with thyroid malignancies.So it is significant to evaluate the prognosis of patients with thyroid cancer.Because of its good water solubility,stability,optical properties and biocompatibility,carbon quantum dots(CQDs)possess important research significance and application prospect in materials science and biomedicine.Electrochemiluminescence biosensor has been a hotspot in analytical chemistry in recent years.The smart combination of electrochemiluminescence analysis technology and biosensor technology brings ECL many potential advantages.By adding an electrochemiluminescent substance into the detection solution or fixing the electroluminescent substance onto the surface of the electrode,the electrochemiluminescence biosensor could quantify the target according to the change of the ECL signal before and after the reaction.The method has played a great role in clinical diagnosis and biological research thanks to its high sensitivity,good reproducibility,good specificity,simple equipment and quick and convenient detection.Therefore,this paper combines the carbon quantum dots with the characteristics of electrochemiluminescence biosensor to develop a highly specific and sensitive CQDs-based electrochemiluminescence biosensor for the qualitative and quantitative detection of proteins.The specifics of the paper are as follows:In the first part of the experiment,utilizing carbon fibers as precursors,nitric acid was used to oxidize carbon fibers under high temperature conditions.The fluorescent carbon quantum dots with different oxidation degree were synthesized by changing the concentration of nitric acid and the reaction time.The surface morphology,surface element analysis and optical properties of the carbon quantum dots were investigated by means of high resolution transmission electron microscopy,fourier transform infrared spectroscopy,X-ray electron spectroscopy,UV,fluorescence and electrochemiluminescence and so on.The results showed that the surface of carbon quantum dots prepared by nitric acid reflux method is rich in oxygen-containing groups,and the higher the oxygen content,the stronger the fluorescence and electro-chemical luminous intensity of carbon.In this article,the mechanism of electrochemiluminescence of carbon quantum dots was explored,and the determination conditions were also optimized.In the second part,a competitive electrochemiluminescence biosensor for detection of thyroglobulin antigen in human serum were constructed on the base of the excellent conductivity of gold nanoparticles and the efficient separation and enrichment of gold nanoparticles.The carbon quantum dots are modified to the surface of thyroglobulin specific antigen(Tg)by amide reaction to form CQDs-Tg.The biotin-modified Tg antibody(bio-antiTg)is incubated with a certain amount of the reaction solution,containing the CQDs-Tg and the Tg antigen to be measured.After that,the Tg antibody were enriched on beads(Strep-MB)with streptavidin groups by the force of biotin-streptavidin,and then adsorbed to the surface of magnetic glassy carbon electrode(MGCE)which was deposited gold nanoparticles,and ultimately meeted the ECL measurement.Under the optimum reaction conditions,the ECL signal of the biosensor showed a good linear relationship with the Tg of the analyte in the range of 0.01 ~ 100 ng/mL,and the detection limit was 17.92 pg/mL.Through the interference experiment with several common tumor markers,the results showed that the sensor owned good specificity and is expected to be further used for the detection of Tg in the actual sample.complexesaffinity. |
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