Electrochemical Impedimetric Immunosensor for Quantitative Detection of Chronic Kidney Disease

• Main Authors: ZHU,PEI-YU, 朱沛妤
• Other Authors: CHUANG,CHENG-HSIN
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/tk8na3

碩士 === 南臺科技大學 === 機械工程系 === 106 === Chronic Kidney Disease (CKD) is a significant global health problem and Taiwan has the highest incidence and prevalence rates of end stage renal disorder in the world. CKD occurs in stages due to a gradual loss in kidney function and is often ignored in its early stages due to its asymptomatic nature. While proteins are generally retained in the blood stream by healthy kidneys, an increase in the urinary albumin or proteinuria is a strong indication of CKD. Thus to ensure early diagnosis and effective treatment of CKD, there is an urgent need for the sensitive and quantitative detection of urinary albumin. In this study, we have fabricated a simple disposable plastic based immunosensor for the detection of human serum albumin (HSA) based on electrochemical impedance spectroscopy (EIS). The electrodes are fabricated via a low cost one-step screen-printing protocol using carbon ink. We have designed and compared the efficacy of two separate immunosensors with different electrode geometries (interdigitated two electrode and three electrode) and modification schemes. For the interdigitated electrodes, differential analysis is performed to compare the response at the test and control site to improve specificity. To enable efficient immobilization of HSA antibodies, we have utilized dielectrophoresis (DEP) to trap nanoprobes (NPs ) on the electrode surface. The NPs consist of micro particles with a polystyrene core and a silver shell that are conjugated to HSA antibodies via covalent chemistry. The normalized impedance variation was calculated at an operating frequency of 10 KHz for which we observe the maximum stable response during immunosensing. Using this immunosensor, we can achieve a limit of detection of 30 µg/mL and the normalized impedance response shows a linear dependence on HSA concentration in the range of 30 – 300 µg/mL. For the three-electrode design, we use a different electrode modification scheme to immobilize the antibodies. First, polyaniline is electro polymerized on the carbon working electrode surface using cyclic voltammetry followed by electrodeposition of gold nanocrystals using linear sweep voltammetry. Conductive polymers enable covalent antibody conjugation and act as redox mediators while gold NCs enable improved charge transfer, good biocompatibility and increased surface areas. Using this sensor we can achieve a limit of 3 µg/mL while also showing a linear response to HSA concentration up to 300 µg/mL. To summarize, we have developed two low cost plastic based immunosensors for CKD detection. Future works will include immunosensing in artificial urine and finally clinical human urine samples and integration of immunosensor with readout module for point of care testing. We believe that this diagnostic system would allow for improved public health monitoring and aid in CKD detection.