Fast Aptamer Generation Method Based on the Electrodynamic Microfluidic Channel and Evaluation of Aptamer Sensor Performance

We demonstrate for the first time a fast aptamer generation method based on the screen-printed electrodynamic microfluidic channel device, where a specific aptamer selectively binds to a target protein on channel walls, following recovery and separation. A malaria protein as a model target, Plasmodium vivax lactate dehydrogenase (PvLDH) was covalently bonded to the conductive polymer layer formed on the carbon channel walls to react with the DNA library in a fluid. Then, the AC electric field was symmetrically applied on the channel walls for inducing the specific binding of the target protein to DNA library molecules. In this case, the partitioning efficiency between PvLDH and DNA library in the channel was attained to be 1.67 x 10(7) with the background of 5.56 x 10(-6), which was confirmed using the quantitative polymerase chain reaction (qPCR). The selectively captured DNAs were isolated from the protein and separated in situ to give five aptamers with different sequences by one round cycle. The dissociation constants (K-d) of the selected aptamers were determined employing both electrochemical impedance spectroscopy (EIS) and the fluorescence method. The sensing performance of each aptamer was evaluated for the PvLDH detection after individual immobilization on the screen-printed array electrodes. The most sensitive aptamer revealed a detection limit of 7.8 +/- 0.4 fM. The sensor reliability was evaluated by comparing it with other malaria sensors.

Automated summary

In this study, a fast aptamer generation method based on a screen-printed electrodynamic microfluidic channel device was successfully demonstrated. By covalently bonding a malaria protein to the carbon channel walls and inducing specific binding via an AC electric field, five different sequences of aptamers were obtained in one round cycle. These aptamers showed high sensitivity for the detection of the target protein, with one aptamer revealing a detection limit of 7.8 +/- 0.4 fM. The reliability of the sensor was evaluated by comparison with other malaria sensors.