Screening of DNA Aptamers against Myoglobin Using a Positive and Negative Selection Units Integrated Microfluidic Chip and Its Biosensing Application

An aptamer screening method using a positive and negative selection units integrated microfluidic chip was introduced. Here, myoglobin (Myo), one of the early markers to increase after acute myocardial infarction, was used as the model. After 7-round selection, the aptamers, which exhibited dissociation constants (K_d) in the nanomolar range (from 4.93 to 6.38 nM), were successfully obtained using a positive and negative selection units integrated microfluidic chip. The aptamer with the highest affinity (K_d = 4.93 nM) was then used for the fabrication of a label-free supersandwich electrochemical biosensor for Myo detection based on target-induced aptamer displacement. The detection limit of this aptamer-based electrochemical biosensor was 10 pM, which was significantly lower than that of those previous antibody-based biosensors for Myo detection. This work may not only develop a strategy for screening aptamer but also offer promising alternatives to the traditional analytical and immunological methods for Myo detection.