Sensitive immunoassay of cardiac troponin I using an optimized microelectrode array in a novel integrated microfluidic e
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RESEARCH PAPER
Sensitive immunoassay of cardiac troponin I using an optimized microelectrode array in a novel integrated microfluidic electrochemical device Yang Li 1 & Shaohua Zuo 1 & Laiqian Ding 1 & Pengpeng Xu 1 & Kun Wang 1 & Yuanchang Liu 2 & Jingmin Li 1 & Chong Liu 1,3 Received: 24 July 2020 / Revised: 15 September 2020 / Accepted: 22 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract A sensitive and portable microfluidic electrochemical array device (μFED) was developed for the immunoassay of trace amounts of human cardiac troponin I (cTnI), which is an attractive biomarker for acute myocardial infarction (AMI). The classical “sandwich” method was adopted for the immunoassay. The capture antibody was immobilized using a self-assembled monolayer (SAM) technique, and the process was reorganized to be compatible with the bonding process. The detection antibody was labeled with alkaline phosphatase (AP) for signal amplification. The performance of the μFED was improved by eliminating the shielding effect of the microelectrode array (MEA) integrated in the μFED. The effects of the interstice and the width of the MEA on the response peak current were analyzed and simulated. The concentration gradient, about 3% of the gradient at the surface, was considered as the criterion for estimation of the optimal interstice between electrodes, and its effectiveness was proved. A stable and miniaturized reference electrode was integrated in the μFED, and its potential deviation was less than 5 mV in 15 min. These efforts resulted in the enhanced immunoassay performance of the μFED. A low limit of detection of about 5 pg/mL was obtained in serum samples, and the response current was proportional to the logarithm of concentration from 50 pg/mL to 1 μg/mL. The immunoassay process was accomplished in 15 min. The μFED was thus qualified and is a promising candidate for point-of-care immunoassay of cTnI. Keywords Immunoassay . μFED . SAMs . Shielding effect
Introduction Acute myocardial infarction (AMI) is one of the most serious cardiovascular diseases and a major cause of morbidity and Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00216-020-02968-z) contains supplementary material, which is available to authorized users. * Jingmin Li [email protected] * Chong Liu [email protected] 1
Key Laboratory for Micro/Nano Technology and System of Liaoning Province, Dalian University of Technology, No.2 Linggong Road, Ganjingzi District, Dalian 116024, Liaoning, China
2
Department of Mechanical Engineering, University College London, Torrington Place, WC1E 7JE, London, UK
3
Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116024, Liaoning, China
mortality. The electrocardiogram (ECG) is the mainstay of initial screening for the diagnosis of AMI, but less than onethird of potential patients admitted to emergency departments exhibit definitive ECG evidence of A
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