Urinary Exosome Isolation and Enrichment as Enabling Liquid Biopsy by Biologically Intact Exosome Separation Technology: BEST

Urine-based liquid biopsy and exosomes constitute exceptional noninvasive techniques for detecting valuable biomarkers associated with diverse diseases. However, current exosome isolation methods struggle to recover sufficient intact exosomes from a large volume of diluted urine, limiting high detection sensitivity. Here, we present a highly sensitive method for detecting exosome markers using microfluidics-based biologically intact exosome separation technology (BEST), which isolates and enriches exosomes from human urine. Numerical simulations demonstrate that hydrodynamic wall repulsion and suction-driven drag forces segregate 100 nm particles representing exosomes from 8 μm particles, indicating apoptotic bodies or larger particles with complete purity, consistent with experiments. We also show a separation purity of 72.4% for urinary exosomes at a suction flow rate of 95 μL/min. Using concentrated exosomes, PCR and Western blotting sensitivities increase by 4.7 and 4.0-fold, respectively, compared with unprocessed pooled urine. Our methodology possesses considerable potential for future molecular diagnostics, necessitating heightened sensitivity.