Small vesicles (sEVs) are closely related to many diseases as they carry various bio-markers. Efficient separation of sEVs from complex biological samples is essential and prerequisite for the following treatment and further disease diagnosis. Here we propose a label-free and biocompatible on-chip magnetic separation system for efficient extraction of sEVs from cell culture supernatant. Through an on-chip ultra-high gradient magnetic field module, a magnetic field gradient close to 100 000 T m⁻¹ is generated inside the separation microchannel. By using fluorescent particles of 200 nm and 1000 nm to simulate sEVs and other bioparticles in a complex sample, the system design and the experimental parameters are optimized. Flow cytometry and a proposed fluorescence intensity analysis method both verify that the recovery rate and purity of 200 nm particles can reach 84.91% and 98.02%, respectively. Then, a biocompatible ferrofluid is utilized in the separation system to separate sEVs from the cell culture supernatant. The results tested by nanoparticle tracking analysis show that the recovery rate and purity of sEVs are 85.80% and 80.45%, superiorly exceeding the performance that the ultracentrifugation method can provide.

中文翻译：

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通过无标记和生物相容的片上磁分离提取小细胞外囊泡

小囊泡 (sEV) 与许多疾病密切相关，因为它们携带各种生物标志物。从复杂的生物样本中有效分离 sEV 是后续治疗和进一步疾病诊断的必要条件和先决条件。在这里，我们提出了一种无标记且生物相容的片上磁分离系统，用于从细胞培养上清液中高效提取 sEV。通过片上超高梯度磁场模块，磁场梯度接近100 000 T m ^-1在分离微通道内产生。通过使用 200 nm 和 1000 nm 的荧光粒子模拟复杂样品中的 sEV 和其他生物粒子，优化了系统设计和实验参数。流式细胞仪和提出的荧光强度分析方法均验证了200 nm颗粒的回收率和纯度分别可以达到84.91%和98.02%。然后，在分离系统中使用生物相容性铁磁流体将 sEV 从细胞培养上清液中分离出来。纳米粒子追踪分析测试结果表明，sEV的回收率和纯度分别为85.80%和80.45%，优于超速离心法所能提供的性能。