Chia-Ho Chu

Dual-aptamer assay for C-reactive protein detection by using field-effect transistors on an integrated microfluidic system

Rapid and accurate diagnosis of C-reactive protein (CRP) is crucial for monitoring cardiovascular diseases because it is a well-known biomarker for evaluating risks of cardiovascular diseases. This study presents a dual-aptamer assay for detection of CRP by using field-effect transistors (FET). This is the first time that two aptamers, which are specific to CRP, were used to form a sandwich assay such that the CRP concentration could be detected by FET devices. Furthermore, a microfluidic system was used to automate the dual-aptamer sandwich assay such that the entire diagnosis process could be automated. In addition to electric signals from the FET device, fluorescent signals were also used to confirm this assay. Experimental results revealed that the first aptamer (1st aptamer) and the second aptamer (c aptamer) could be specifically binded with target CRP. Furthermore, the microfluidic chip integrated with FET can be re-used if the binded CRP and 2nd aptamer was eluted. Besides, in order to prevent the interference materials like proteins, cells and any nonspecific molecules from adhering onto the gate region of the FET device even after immobilization of 1st aptamer, we used ethanolamine as the blocking agent to prevent nonspecific adhesion. The experimental results confirmed that blocking using ethanolamine could successfully prevent nonspecific binding.

An integrated microfluidic system with field-effect-transistor-based biosensors for automatic highly-sensitive C-reactive protein measurement

Rapid and accurate diagnosis of C-reactive protein (CRP) is crucial for preventing cardiovascular diseases because it is a well-known biomarker for evaluating risks of cardiovascular diseases. Our previous work has shown that a microfluidic system equipped with a field-effect-transistor (FET)-based biosensor could detect CRP in 0.1X PBS and provided a limit of detection (LOD) of 26 pM CRP without gate bias. To improve the LOD, a new microfluidic device with a new methodology for measuring FET-based biosensors is presented in this study. Not only can the proposed system work in a solution with a physiological salt concentration but it also detects CRP with ultra-high sensitivity in an automatic fashion. This is the first time that a FET-based biosensor can effectively and automatically detect CRP in a physiological salt concentration without decreasing the sensitivity. The LOD of CRP using aptamer-immobilized AlGaN/GaN high-electron-mobility transistors (HEMTs) was experimentally found to be 1fM, demonstrating the superior performance of this new technique. It may be used as a point-of-care device for CRP detection in the near future.