Highly enhanced electrochemiluminescent strategy for tumor biomarkers detection with in situ generation of l-homocysteine for signal amplification

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• 作者：Haijun Wang ; Yaqin Chai ; ^{yqchai@swu.edu.cn" class="auth_mail} ; Ruo Yuan ^{yuanruo@swu.edu.cn" class="auth_mail} ; Yaling Cao ; Lijuan Bai
• 关键词：Electrochemiluminescence ; Peroxydisulfate ; In situ ; Coreactant ; Accumulate ; Immunosensor
• 刊名：Analytica Chimica Acta
• 出版年：7 March, 2014
• 年：2014
• 卷：815
• 期：Complete
• 页码：16-21
• 全文大小：1751 K

文摘

In this work, an ultrasensitive peroxydisulfate electrochemiluminescence (ECL) immunosensor using in situ generation of l-homocysteine (l-Hcys) for signal amplification was successfully constructed for detection of carcinoembryonic antigen (CEA). In the reaction of biological methylation, S-adenosyl-l-homocysteine hydrolase (SAHH) catalyzed the reversible hydrolysis of S-adenosyl-l-homocysteine (SAH) to produce l-Hcys, which was inducted into ECL system to construct the immunosensor for signal amplification in this work. Simultaneously, Gold and palladium nanoparticles functionalized multi-walled carbon nanotubes (Au-PdNPs@MWCNTs) were prepared, which were introduced to immobilize the secondary antibody (Ab₂) and SAHH with high loading amount and good biological activity due to their improved surface area and excellent biocompatibility. Then the proposed ECL immunosensor was developed by a sandwich-type format using Au-PdNPs@MWCNTs-SAHH-Ab₂ as tracer and graphene together with AuNPs as substrate. Besides the enhancement of Au-PdNPs, the enzymatic catalysis reaction also amplified the ECL signal dramatically, which was achieved by efficient catalysis of the SAHH towards the hydrolysis of SAH to generate improved amount of l-Hcys in situ. Furthermore, due to the special interaction between Au-PdNPs and -SH or -NH₂ in l-Hcys, l-Hcys would gradually accumulate on the surface of the immunosensor, which greatly enhanced the concentration of l-Hcys on the immunosensor surface and further improved the ECL intensity. With the amplification factors above, a wide linear ranged from 0.1 pg mL^鈭? to 80 ng mL^鈭? was acquired with a relatively low detection limit of 33 fg mL^鈭? for CEA.