급성심근경색 바이오마커 검출을 위한 포토다이오드 어레이 바이오칩 개발

Abstract

Early detection of cardiac biomarkers plays a critical role in the diagnosis of acute myocardial infarctions (AMI). Here, we present a photodiode array (PDA) biochip using a bipolar semiconductor that can detect cardiac biomarkers such as myoglobin (Myo) and cardiac troponin I (cTnI) with sensitivity and a large dynamic range. The PDA chip which consists of a 12 x 12 array of photodiodes with each photodiode having a diameter of 200 µm acts as both a support for antibody immobilization and as a two-dimensional detector. The monoclonal cardiac antibody was immobilized on the chip based on covalent bonding via silanization. A sandwich immunoassay was performed on the photodiode area of the PDA chip. The gold nanoparticles (AuNPs) bound to the probe antibodies on the PDA chip surface via avidin-biotin interaction were used for signal amplification through silver enhancement. The deposited silver metals blocked the light-emitting diodes (LEDs) light irradiated from above, resulting in a decrease in the produced voltage. The decreased voltage was directly proportional to the amount of target antigens present in the sample solution, allowing the specific detection and the quantitative analysis of the cardiac markers. The linear ranges of quantification of myoglobin (Myo) and cardiac troponin I (cTnI) were from 10-5 to 10-1 mg/ml (R2 = 0.998, n = 3 and limit of detection (LOD) of 2.2 ng/ml) and from 10-8 to 10-4 mg/ml (R2 = 0.992, n = 3 and LOD = 4.0 pg/ml), respectively, which were lower than the clinical cutoff levels (Myo: 70-200 ng/ml; cTnI: 0.01-0.1 ng/ml). The device could be extended to the detection of other biomolecules, either individually or simultaneously.