Quantum dots based electrochemiluminescent immunosensor by coupling enzymatic amplification for ultrasensitive detection of clenbuterol

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• 作者：Xun Yao ; Panpan Yan ; Qinghui Tang ; Anping Deng ; Jianguo Li
• 关键词：Electrochemiluminescence ; Biosensors ; CdSe quantum dots ; Enzymatic amplification ; Clenbuterol
• 刊名：Analytica Chimica Acta
• 出版年：2013
• 出版时间：10 October, 2013
• 年：2013
• 卷：798
• 期：Complete
• 页码：82-88
• 全文大小：1667 K

文摘

An ultrasensitive electrochemiluminescence (ECL) immunosensor based on CdSe quantum dots (QDs) has been designed for the detection of clenbuterol. The immunosensor was fabricated by layer by layer and characterized with atomic force microscopic images (AFM) and electrochemical impedance spectra (EIS). In oxygen-saturated pH = 9.0 Tris-HCl buffer, a strong ECL emission of QDs could be observed during the cathodic process due to the H₂O₂ product from electrochemical reduction of dissolved oxygen. Upon the formation of immunocomplex, the second antibody labeled with horseradish peroxidase was simply immobilized on the electrode surface. The ECL emission decreased since steric hindrance of the immunocomplex slowed down the electron-transfer speed of dissolved oxygen, and also could be greatly amplified by an enzymatic cycle to consume the self-produced coreactant. Using clenbuterol as model analyte, the ECL intensity was determined by the concentration of competitive immunoassay of clenbuterol with a wide calibration in the range of 0.05 ng mL^?1 to 1000 ng mL^?1, and a low detection limit was 0.02 ng mL^?1. The immunosensor shows good stability and fabrication reproducibility. It was applied to detecting practical samples with the satisfactory results. This immunosensing strategy opens a new avenue for detection of residue and application of QDs in ECL biosensing.