Rapid purification of sub-micrometer particles for enhanced drug release and microvesicles isolation

Efficient separation of sub-micrometer synthetic or biological components is imperative in particle-based drug delivery systems and purification of extracellular vesicles for point-of-care diagnostics. Herein, we report a novel phenomenon in spiral inertial microfluidics, in which the particle transient innermost distance (D_inner) varies with size during Dean vortices-induced migration and can be utilized for small microparticle (MP) separation; aptly termed as high-resolution Dean flow fractionation (HiDFF). The developed technology was optimized using binary bead mixtures (1–3 μm) to achieve ~100-to 1000-fold enrichment of smaller particles. We demonstrated tunable size fractionation of polydispersed drug-loaded poly(lactic-co-glycolic acid) particles for enhanced drug release and anti-tumor effects. As a proof-of-concept for microvesicles studies, circulating extracellular vesicles/ MPs were isolated directly from whole blood using HiDFF. Purified MPs exhibited well-preserved surface morphology with efficient isolation within minutes as compared with multi-step centrifugation. In a cohort of type 2 diabetes mellitus subjects, we observed strong associations of immune cell-derived MPs with cardiovascular risk factors including body mass index, carotid intima-media thickness and triglyceride levels (Po0.05). Overall, HiDFF represents a key technological progress toward high-throughput, single-step purification of engineered or cell-derived MPs with the potential for quantitative MP-based health profiling.