Interplay of electric field and pressure-driven flow inducing microfluidic particle migration

Abstract The lateral migration of colloidal particles inside a microfluidic channel has gained attention due to being both fundamentally intriguing and applicable for particle separation, such as cancer cell isolation or extracellular vesicle purification. Applying an external electric field combined with a pressure-driven flow induces such lateral migrations. In this study, new modes of lateral particle migration have been found by experimentally investigating 6 µm particles in the co-presence of electric field and pressure-driven flow. The experiments revealed the importance of the relative strengths of electric field and pressure gradient in determining particle lateral positioning. We hypothesize that the nonuniformity of the polarization caused by the external electric field and the rotation of the particle due to the background pressure-driven flow result in these modes of transverse migration. These new migration patterns are further utilized to perform microparticle separation and, more importantly, present a novel separation modality

Enrichment of bovine milk-derived extracellular vesicles using surface-functionalized cellulose nanofibers

Abstract The isolation of extracellular vesicles (EVs) from milk, a complex mixture of colloidal structures having a comparable size to EVs, is challenging. Although ultracentrifugation (UC) has been widely used for EV isolation, this has significant limitations, including a long processing time at high g-force conditions and large sample volume requirements. We introduced a new approach based on nature nanoentities cellulose nanofibers (CNFs) and short time and low g-force centrifugation to isolate EVs from various milk fractions. The flexible and entangled network of CNFs forms nanoporous, which entraps the EVs. Further, positively charged CNFs interact with anionic EVs through an electrostatic attraction, promoting their isolation with efficiency comparable with UC. The functionality and toxicity of isolated milk EVs were tested in Caco2 cells. Overall, the newly developed approach provides straightforward isolation and biocompatibility and preserves the natural properties of the isolated EVs, enabling further applications