마이크로바이오칩 기반의 암 바이오마커 검출용 전기 면역 센서에 대한 연구

Abstract

Over the past decades, interest in health has increased dramatically due to remarkable advances in the development of biomedical and clinical applications. Cancer continues to be one of the leading causes of mortality each year; hence, various medical technologies cancer diagnosis and treatment are continuously being researched and developed. Despite these advances, the expenses incurred on cancer patients are considerably high and a cure has yet to be found. As a result, early diagnosis using a cancer biomarker may prove to be invaluable. Immunoassays have been used extensively for cancer diagnosis because of the specificity and sensitivity of antigen?antibody interactions. However, the conventional immunoassay is laborious and expensive and requires prolonged time. In addition, because of their associated large-scale detection devices, it is difficult to conduct immunoassays at Point of Care Testing (POCT) facilities. Miniaturized analytical systems have recently been developed in an effort to overcome these obstacles. One particular system, the microbiochip-based immunosensor, has become the focus of research interest for cancer biomarker diagnostics. This system features high sensitivity and a simplified reaction procedure. Moreover, use of a small microbiochip in an electrical detection system may make diagnostics more readily accessible to POCT facilities. In this study, three cancer biomarkers, alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA) and prostate-specific antigen (PSA)?widely used for diagnosis of liver, colon and prostate cancer, respectively?were assayed through an electrical detection system on a polydimethylsiloxane (PDMS)-glass microbiochip. The first part of our study focused on a single-detection chip, and the second part of our study focused on a multi-detection chip. In the first part of the study, we fabricated platinum (Pt) electrodes on a glass substrate to enable detection of electrical signals and then formed a microchamber and pillar-type microfilter in the PDMS layer. Microbeads were used to filter and immobilize capture antibodies. Immunogold-silver staining (IGSS) was then used to amplify electrical signals corresponding to the bound antibodies. Using the fabricated chip and detection devices, we optimized the experimental conditions (e.g., flow rate, reaction time, and silver enhancer treatment time) of the three cancer biomarkers and measured the electrical signals of each biomarker using a multimeter. In the second part of the study, we designed a microbiochip for simultaneous sensing multiple biomarkers. The multi-detection chip comprised the four reaction microchambers (for AFP, CEA, PSA, and control) and four Pt electrodes. The electrical signal obtained from the four electrodes was measured by a multiplexer switch module (PXI 2527) and digital multimeter module (PXI 4072), which were controlled by the LabView (Ver. 8.2) software. The results of this study showed that the overall assay time was reduced from 3?5 h to approximately 55 min as compared to conventional immunoassays. A detection limit as low as 1 ng/mL was attained using this microfluidic immunosensor, indicating that our chip-based analytic system may be useful in diagnosing many forms of cancer.