Electrochemical Immunoassay Based on Indium Tin Oxide Activity Toward a Alkaline Phosphatase
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Original Article
Electrochemical Immunoassay Based on Indium Tin Oxide Activity Toward a Alkaline Phosphatase Sunga Song1, Young Joo Kim1, Ik-Soo Shin & Woo Kyeong Seong1
2,
* , Won-Hyo Kim1, Kook-Nyung Lee
1,
*
Received: 16 October, 2019 / Accepted: 25 November, 2019 / Published online: 17 December, 2019 â’¸The Korean BioChip Society and Springer 2019
Abstract In vitro diagnostic technologies, used to evaluate disease status at the point-of-care (POC), are of urgent importance to improve diagnostic capabilities in bladder cancer. However, currently available approaches have a limitation because of their lack of detection for early-staged cancer. Herein, we developed an electrochemical immunosensor for the POC diagnosis of bladder cancer in which the enzyme alkaline phosphatase (ALP) and its metabolite, ascorbic acid 2-phosphate (AAP), are employed as the electrochemical label and redox signaling unit. The indium tin oxide (ITO) electrode exhibits no redox activity toward the AAP substrate, whereas its metabolic add of ascorbic acid (AA) produces strong oxidation current under the voltammetric measurement. The ITO electrode and the ALP enzyme are revealed as an excellent combination for the development of the electrochemical immunosensors in both directand sandwich-type immunoassay approach. Determination of apolipoprotein-A4 and metallopeptidase9, two representative bladder cancer markers, were used to evaluate our approach, and excellent quantification with standard deviation 10 % was achieved. Overall, our results showed that our method offers an opportunity for the development of a variety of new forms of portable POC diagnostic devices with low cost and excellent performance. 1
Human IT Convergence Research Center, Korea Electronics Technology Institute, 25, Saenari-ro, Bundang-gu, Seongnam-si, Gyeonggi 13509, Republic of Korea 2 Department of Chemistry and ICMC Conversions Technology, Soongsil University, Seoul 06978, Republic of Korea *Correspondence and requests for materials should be addressed to I.-S. Shin ( [email protected]) and K.N. Lee ( [email protected])
Keywords: ITO sensing electrode, The enzyme ALP, sandwich immunoassay, Enzyme labeling
Introduction In vitro diagnostic technology, used to evaluate disease status at the point-of-care (POC) is aimed at prompt diagnosis and prognosis of disease as well as evaluation of the health status of the individual1-6. Accordingly, the development of portable immunosensors for prompt POC diagnosis while simultaneously identifying diseases at an early stage is in urgent need. Enzyme-linked immunosorbent assay (ELISA) is widely used for biomarker detection. ELISA can quantitatively and qualitatively analyze an antigen or antibody using an antigen-antibody reaction7-15. This method utilizes enzymes as a detection label and uses the principle of measuring the quantitative change of the reaction product of the enzyme in proportion to the concentration of the target antigen. Various types of immunoassay methods can be applied to effectively determinate targe
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