Microfluidic devices for the isolation and label-free identification of circulating tumor cells

The isolation and identification of circulating tumor cells (CTCs) from blood samples provides a great opportunity for prevention of metastatic cancer and assist early diagnosis and treatment of cancer. However, separation and recovery of CTCs using conventional analytical technologies remains challenging due to the low concentration of CTCs in blood. Microfluidics technologies have recently been proposed as advanced platform for isolation of CTCs owing to its ease of integration, rapid and continuous processing, and separation of cells along multiple geometric possibilities in manipulating micron-sized particles. This review provides a critical and comprehensive outlook to recent advancements, challenges, and opportunities of microfluidic, label-free strategies for highly CTCs isolation from biological samples. This includes a detailed summary of microfluidic-based methods for cell sorting, which have been organized into active and passive methods with a detailed discussion on the practical applications of each process in improving the performance for isolation of CTCs, looking at their working principles and respective advantages. We elaborated on some of these methods’ current limitations and prospective opportunities, which we believe will help to drive further innovations and adoption of microfluidic-based CTCs isolation, with a large potential for clinical applications in cancer treatment and diagnostics and fundamental study of metastatic processes.