A microfluidic electrochemical immunosensor for detection of CEA and Ki67 in 3D tumor spheroids

Microfluidic chip-based electrochemical sensors have been developed to detect cancer biomarkers and monitor changes in the tumor microenvironment. However, the limitation of detecting only a single biomarker restricts their utility as accurate diagnostic tools. Simultaneous detection of multiple tumor biomarkers is important for early diagnosis of cancer. In this work, we report the development of a microfluidic-based electrochemical immunosensor platform capable of simultaneously observing multiple biomarkers expressed by three dimensions (3D) cell spheroids. The sensor platform employs a nanocomposite electrode material consisting of gold nanoparticles and carbon nanotubes, which enables sensitive and selective detection. The sensor was fabricated using 3D and printed circuit boards (PCB) printing techniques, demonstrating the feasibility of cost-effective manufacturing. The developed platform was able to quantitatively detect two key cancer biomarkers, carcinoembryonic antigen (CEA) and Ki67, with limits of detection of 0.97 ng/mL for each. Furthermore, the sensor was successfully utilized to observe the knockdown of these biomarkers, showcasing its potential for both diagnostic and therapeutic monitoring applications. These results suggest that the presented electrochemical sensor platform provides a promising lab-on-a-chip technology for comprehensive 3D cell spheroid-based cancer biomarker analysis, which could have significant implications for future clinical diagnostics and personalized medicine.