Microfluidic Exosome Analysis toward Liquid Biopsy for Cancer

Assessment of a tumor's molecular makeup using biofluid samples, known as liquid biopsy, is a prominent research topic in precision medicine for cancer, due to its noninvasive property allowing repeat sampling for monitoring molecular changes of tumors over time. Circulating exosomes recently have been recognized as promising tumor surrogates because they deliver enriched biomarkers, such as proteins, RNAs, and DNA. However, purification and characterization of these exosomes are technically challenging. Microfluidic lab-on-a-chip technology effectively addresses these challenges owing to its inherent advantages in integration and automation of multiple functional modules, enhancing sensing performance, and expediting analysis processes. In this article, we review the state-of-the-art development of microfluidic technologies for exosome isolation and molecular characterization with emphasis on their applications toward liquid biopsy-based analysis of cancer. Finally, we share our perspectives on current challenges and future directions of microfluidic exosome analysis.