Surface chemistry for cell capture in microfluidic systems

Cell separation or sorting plays an important role in basic research and clinical applications such as the differentiation of stem cells [1,2], detection of circulating tumor cells (CTCs) [3,4] and quantification of CD4⁺ T lymphocytes in peripheral blood [5,6]. Conventionally, fluorescence-activated cell sorting or magnetic cell sorting methods have been widely used to separate cells of interest from a heterogeneous cell mixture. However, these methods require technical support, length sample preparation, and well-trained operators, which limit their applications in resource-limited and point-of-care settings. To address these drawbacks, various microfluidic devices have been designed and tested, targeting increased portability, reduced consumption of samples and reagents, decreased process complexity, and shortened sample-to-result time. In addition, the manufacturing of microfluidic devices can easily be scaled up, significantly reducing the cost of health care, even for developed countries. The microfluidic device can be further integrated into an automated system to reduce human errors. The advantages of microfluidic systems offer opportunities for improving health care in resource-limited settings, such as monitoring AIDS treatments using CD4 cell capturing devices [5,6].