Prostate-specific antigen (PSA) was used as the model, an ultrasensitive label-free electrochemiluminescent immunosensor was developed based on graphene quantum dots. Au/Ag-rGO was sythsized and used as electrode material to load a great deal of graphene quantum dots due to the large surface area and excellent electron conductivity. After aminated graphene quantum dots and acarboxyl graphene quantum dots were modified onto the electrode, the ECL intensity was much high using K 2 S 2 O 8 as coreactant. Then, antibody of PSA was immobilized on the surface of modified electrode surface through the adsorption of Au/Ag toward proteins, leading to the decrease of the ECL intensity. As proven by ECL spectra test and electrochemical impedance spectroscopy (EIS) analysis, the fabrication process of the immunosensor is successful. Under the optimal conditions, the ECL intensity decreased linearly with the logarithm of PSA concentration in the range of 1 pg/mL ~ 10 ng/mL. The detection limit achieved is 0.29 pg/mL. The immunosensor results were validated through the detection of PSA in serum samples with satisfactory results. Due to excellent stability, high sensitivity, acceptable repeatability and selectivity, the immunosensor has promising applications in disease and drug analysis.
Yuxiao Yang,Min Jiang,Kaihang Cao,Mei Wu,Chulei Zhao,Hongling Li,Chenglin Hong
An electrochemical immunosensor for quantitation of carcinoembryonic antigen (CEA) based on Au-Ag/ [email protected] nanocomposites for dual signal amplification strategy was designed. Polydopamine-coated Ag/graphene hybrids were synthesized by one-step reduction and functionalization, and the dopamine was introduced to replace some reducing agents that are harmful to organisms. Silver nanoparticles modified on the electrodes produced sensitive electrochemical redox peaks. When different amounts of protein (antigen, antibody, bovine serum protein, etc.) were adsorbed on the surface of nano-silver, the surface of nano-silver was covered. The electrochemical redox peak of silver particles decreased due to the change of the effective area of bare silver particles which could react with electrodes. In addition, CEA-antibody (anti-CEA) was immobilized into a biocompatible nanocomposite of Au nanoparticles as a conductive matrix, and CEA-antibody (anti-CEA) was combined with Ag/ [email protected] to form a dual signal amplifying element. Under optimal condition, the linear relationship was obtained from 0.001 ng mL −1 to 80 ng mL −1 between current signal and CEA concentration with a detection limit of 0.286 pg mL −1 (signal-to-noise ratio is 3). The label-free electrochemical immunosensor has been successfully applied to human serum detection due to good selectivity , stability and reproducibility.
危险品化学品经营许可证（带存储）