Competitive electrochemical immunoassay for detection of ¦Â-amyloid (1-42) and total ¦Â-amyloid peptides using p-aminophenol redox cycling

详细信息    查看全文

• 作者：Lin Liu ; Qige He ; Feng Zhao ; Ning Xia ; Huijing Liu ; Sujuan Li ; Ruili Liu ; Hui Zhang
• 关键词：Electrochemical immunoassay ; Alkaline phosphatase ; Redox cycling ; p-Aminophenol ; ¦Â-Amyloid ; Alzheimer's disease
• 刊名：Biosensors and Bioelectronics
• 出版年：2014
• 出版时间：15 January, 2014
• 年：2014
• 卷：51
• 期：Complete
• 页码：208-212
• 全文大小：531 K

文摘

¦Â-Amyloid (1-42) peptide (A¦Â(1-42)) is believed to be important for diagnosis and prognosis of Alzheimer's disease (AD) serving as a reliable molecular biomarker. However, the levels of A¦Â(1-42) may differ by gender and age; thus, assay of A¦Â(1-42) only might be unable to discriminate between AD and health or other types of dementia. In this work, we reported a sensitive and selective electrochemical method for detection of both A¦Â(1-42) and total A¦Â using p-aminophenol (p-AP) redox cycling on antibody-modified gold electrodes. Specifically, the conjugates performed between streptavidin-conjugated alkaline phosphatase (SA-ALP) and biotinylated A¦Â peptides were captured by the antibody-modified electrodes, which induced the production of electrochemically active p-AP from the p-aminophenyl phosphate (p-APP) substrate. In the presence of tris(2-carboxyethyl)phosphine (TCEP), p-AP could be cycled after its electro-oxidization on the electrode, enabling the increase of the anodic current. Because native A¦Â competed with the conjugates to bind the anchored antibody, the signal decreased with the increase of native A¦Â concentration. A detection limit of 5 pM was achieved. To demonstrate the viability of the method for analysis of A¦Â(1-42) and total A¦Â in real sample, artificial cerebrospinal fluid (aCSF) containing A¦Â(1-40), A¦Â(1-42) and A¦Â(1-16) was tested. We believe that the simultaneous detection of A¦Â(1-42) and total A¦Â would be valuable for the early diagnosis of AD.