A microfluidic electrochemical aptasensor for highly sensitive and selective detection of A549 cells as integrin α6β4-containing cell model via IDA aptamers

There is a growing interest in developing microfluidic biosensors for the accurate and reproducible analysis of various biomarkers obtained from liquid biopsy. This paper reports a novel microfluidic electrochemical aptasensor for determination of A549 cells as integrin α6β4-containing cell model and circulating tumor cell (CTC) model of NSCLC, based on target-induced structure switching mode. The conformational change of IDA aptamer structure with an affinity towards A549 cells, in the absence and presence of A549 cells allowed selective and sensitive detection of A549 cells. The microfluidic biosensor consisted of a microchip integrated with a screen-printed gold electrode functionalized with SH-IDA aptamers via covalent chemistry. Target solution containing A549 cells in Phosphate-buffered saline could be introduced to the microchip for analysis. Upon exposing to redox probe, a reduction in peak current occurred. Required flow sequencing for various steps of the detection protocol was performed using on-chip gas-actuated microvalves with programmable operation. The microfluidic biosensor provided a wide linear dynamic range of 50-5 × 105 cells/mL and allowed determination of A549 cells with a detection limit of 14 cells/mL. Furthermore, the microfluidic biosensor was efficiently used for detection of A549 cells in complex matrices such as human serum. Our novel microfluidic aptasensor presents an enabling analytical platform to perform various detections of low volume biomarkers with high accuracy and reproducibility.