Guo Han, Wang Dayin, Feng Shilun, Zhang Kaihuan, Luo Yuan, Zhao Jianlong
State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, People's Republic of China.
Biomicrofluidics. 2024 Jun 26;18(3):034107. doi: 10.1063/5.0208417. eCollection 2024 May.
Small extracellular vesicles (sEVs) are extracellular vesicles with diameters ranging from 30 to 150 nm, harboring proteins and nucleic acids that reflect their source cells and act as vital mediators of intercellular communication. The comprehensive analysis of sEVs is hindered by the complex composition of biofluids that contain various extracellular vesicles. Conventional separation methods, such as ultracentrifugation and immunoaffinity capture, face routine challenges in operation complexity, cost, and compromised recovery rates. Microfluidic technologies, particularly viscoelastic microfluidics, offer a promising alternative for sEV separation due to its field-free nature, fast and simple operation procedure, and minimal sample consumption. In this context, we here introduce an innovative viscoelastic approach designed to exploit the viscosity gradient-induced force with size-dependent characteristics, thereby enabling the efficient separation of nano-sized particles and sEVs from larger impurities. We first seek to illustrate the underlying mechanism of the viscosity gradient-induced force, followed by experimental validation with fluorescent nanoparticles demonstrating separation results consistent with qualitative analysis. We believe that this work is the first to report such viscosity gradient-induced phenomenon in the microfluidic context. The presented approach achieves ∼80% for both target purity and recovery rate. We further demonstrate effective sEV separation using our device to showcase its efficacy in the real biological context, highlighting its potential as a versatile, label-free platform for sEV analysis in both fundamental biological research and clinical applications.
小细胞外囊泡（sEVs）是直径在30至150纳米之间的细胞外囊泡，含有反映其来源细胞的蛋白质和核酸，并作为细胞间通讯的重要介质。生物流体的复杂组成包含各种细胞外囊泡，这阻碍了对sEVs的全面分析。传统的分离方法，如超速离心和免疫亲和捕获，在操作复杂性、成本和回收率方面面临常规挑战。微流控技术，特别是粘弹性微流控技术，由于其无场性质、快速简单的操作程序和极少的样品消耗，为sEV分离提供了一种有前景的替代方法。在此背景下，我们在此介绍一种创新的粘弹性方法，旨在利用具有尺寸依赖性特征的粘度梯度诱导力，从而实现从较大杂质中高效分离纳米级颗粒和sEVs。我们首先试图阐明粘度梯度诱导力的潜在机制，随后用荧光纳米颗粒进行实验验证，证明分离结果与定性分析一致。我们相信这项工作是首次在微流控背景下报道这种粘度梯度诱导现象。所提出的方法在目标纯度和回收率方面均达到了约80%。我们进一步使用我们的设备展示了有效的sEV分离，以证明其在实际生物学环境中的功效，突出了其作为基础生物学研究和临床应用中用于sEV分析的通用、无标记平台的潜力。
