Full integration of nucleic acid extraction and detection into a centrifugal microfluidic chip employing chitosan-modified microspheres

Microfluidic devices especially centrifugal ones have attracted great attention in the nucleic acid testing field, due to their automation, high efficiency, and simple operation. In which, nucleic acid extraction is the basic step, laying a foundation for the downstream amplification and detection procedures. Therefore, the integration of nucleic acid extraction on the chip is expected to achieve cost-efficiency, high-speed automation, diagnostic accuracy, and reaction robustness with the respect to real-time detection. In this work, we employ chitosan-modified magnetic microspheres for pH-induced nucleic acid extraction and integrate this approach into a centrifugal microfluidic chip. The microfluidic system comprises cell lysis, nucleic acids capture and release, isothermal amplification, and real-time fluorescence detection, which is manipulated by centrifugal force and magnetic control. The system exhibits comparable extraction and detection performance in respect of acceptable nucleic acid concentration and purity, high detection specificity and stability, as well as fast detection duration. These efforts to improve the integrated microfluidic detection chip could benefit the portable, efficient and simple nucleic acid diagnosis, especially under the resource-limited circumstance.