Uniform distribution of microspheres based on pressure difference for carcinoma-embryonic antigen detection

Microspheres coated with specific biomolecules have been broadly employed to detect tumor markers. In this study, we developed a novel microfluidic platform based on pressure difference for the uniform distribution of microspheres and applied this platform for carcinoma-embryonic antigen detection with quantum dots probes. Within our microfluidic device, micropost arrays were designed to ensure that the trapped microspheres formed dot arrays to overcome the shortcomings of clogging and loss of microspheres, which typically occurred in currently used structures for microsphere capture. A sandwich immunoassay for the detection of typical cancer biomarker CEA was successfully performed on the microfluidic device with all reagents reacted together, which led to reduced experimental time and simple operations. As a result, a limit of detection of 0.5 ng/mL for carcinoma-embryonic antigen detection was achieved, and the calibration curve fitted the Langmuir model, which showed high clinical consistency with serum sample detection. To further investigate the performance of our system, trap efficiency and uniform ratio of microfluidic structure, and specificity of the experiment were evaluated and showed good consequences. The proposed microfluidic immunoassay system with advantages of high sensitivity and specificity, reduced time cost, and facile operations, indicates a promising potential in clinical diagnosis.