From Exosomes to Circulating Tumor Cells: Using Microfluidics to Detect High Predictive Cancer Biomarkers

Early cancer screening and effective diagnosis is the most effective form to diminish the number of cancer-related deaths. Liquid biopsy constitutes an attractive alternative to tumor biopsy due to its non-invasive nature and sample accessibility, which permits effective screening and patient monitoring. Within the plethora of biomarkers present in circulation, liquid biopsy has mainly been performed by analyzing circulating tumor cells, and more recently, extracellular vesicles. Tracking these biological particles could provide valuable insights into cancer origin, progression, treatment efficacy, and patient prognosis. Microfluidic devices have emerged as viable solutions for point-of-care cancer screening and monitoring due to their user-friendly operation, low operation costs, and capability of processing, quantifying, and analyzing these bioparticles in a single device. However, the size difference between cells and exosomes (micrometer vs nanometer) requires an adaptation of microfluidic isolation approaches, particularly in label-free methodologies governed by particle and fluid mechanics. This chapter will explore the theory behind particle isolation and sorting in different microfluidic techniques necessary to guide researchers into the design and development of such devices.