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.

人们越来越关注开发微流体生物传感器，以准确和可重复地分析从液体活检中获得的各种生物标志物。本文报道了一种新型微流控电化学适体传感器，用于测定 A549 细胞作为含整合素 α6β4 的细胞模型和 NSCLC 的循环肿瘤细胞 (CTC) 模型，基于靶标诱导结构转换模式。在 A549 细胞不存在和存在的情况下，IDA 适配体结构的构象变化对 A549 细胞具有亲和力，允许选择性和灵敏地检测 A549 细胞。微流体生物传感器由一个微芯片组成，该芯片集成了一个丝网印刷的金电极，通过共价化学用 SH-IDA 适体功能化。可以将磷酸盐缓冲盐水中含有 A549 细胞的目标溶液引入微芯片进行分析。暴露于氧化还原探针后，峰值电流降低。使用具有可编程操作的片上气动微阀执行检测协议的各个步骤所需的流量排序。微流体生物传感器提供了 50–5 × 10 的宽线性动态范围^{5 个} 细胞/mL，允许测定 A549 细胞，检测限为 14 个细胞/mL。此外，微流体生物传感器可有效用于检测复杂基质（如人血清）中的 A549 细胞。我们的新型微流体适体传感器提供了一个支持分析平台，可以高精度和可重复性地对低体积生物标志物进行各种检测。