Label-Free Capacitive Aptasensor for Thrombin

• Main Authors: Hsin-Ju Chen, 陳欣儒
• Other Authors: 鄭宗記
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/46002839286841802039

碩士 === 國立臺灣大學 === 生物產業機電工程學研究所 === 100 === Capacitive biosensors are label-free and promising for developing hand-held devices and point-of-care applications. However, conventional micro-fabricated capacitive sensors such as those based on interdigitated electrodes faced the challenges including delicate manufacture and non-uniform distribution of electric field. Furthermore, electrochemical impedance spectroscopy for capacitance measurements usually required extra addition of redox species to enhanced sensitivity. A label-free and sensitive capacitive aptasensor was developed with simple design based on electrode pairs. The electrode pair was the transducer of the capacitive aptasensor, which was composed of a gold electrode (from compact discs) and an indium tin oxide (ITO) film with micrometer separation by a double-side PET tape. On the gold electrode was layered with aptamers as the bio-recognition elements and then a self-assembled monolayer of 1-dodecanethiol to prevent non-specific protein binding. Electrochemical characterization proved that the self-assembly monolayer also formed effective insulating layer adequate for capacitive sensing. Thrombin was selected as a model analyte to validate the assay. The capacitance change originated from thrombin binding with aptamers was measured with a home-made capacitance sensing circuit by switched capacitor technology. The linear range for thrombin detection in human serum was from 10-11 to 10-6 M with a regression coefficient of 0.97. Non-specific binding of bovine serum albumin (BSA) and human serum albumin (BSA) were not observed in the proposed aptasensor. This work demonstrated the successful application of label-free capacitive aptasensor for thrombin detection. It could be applied in the detection of other target proteins by replacing different aptamers.