Center for Life Nano- & Neuro-Science, Italian Institute of Technology, Rome, Italy.
Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy.
Lab Chip. 2023 Apr 12;23(8):2039-2047. doi: 10.1039/d2lc01179d.
Flow cytometers and fluorescence activated cells sorters (FCM/FACS) represent the gold standard for high-throughput single-cell analysis, but their usefulness for label-free applications is limited by the unreliability of forward and side scatter measurements. Scanning flow cytometers represent an appealing alternative, as they exploit measurements of the angle-resolved scattered light to provide accurate and quantitative estimates of cellular properties, but the requirements of current setups are unsuitable for integration with other lab-on-chip technologies or for point-of-care applications. Here we present the first microfluidic scanning flow cytometer (μSFC), able to achieve accurate angle-resolved scattering measurements within a standard polydimethylsiloxane microfluidic chip. The system exploits a low cost linearly variable optical density (OD) filter to reduce the dynamic range of the signal and to increase its signal-to-noise ratio. We present a performance comparison between the μSFC and commercial machines for the label free characterization of polymeric beads with different diameters and refractive indices. In contrast to FCM and FACS, the μSFC yields size estimates linearly correlated with nominal particle sizes ( = 0.99) and quantitative estimates of particle refractive indices. The feasibility of using the μSFC for the characterization of biological samples is demonstrated by analyzing a population of monocytes identified based on the morphology of a peripheral blood mononuclear cells sample, which yields values in agreement with the literature. The proposed μSFC combines low setup requirements with high performance, and has great potential for integration within other lab-on-chip systems for multi-parametric cell analysis and for next-generation point-of-care diagnostic applications.
流式细胞仪和荧光激活细胞分选器（FCM/FACS）代表高通量单细胞分析的金标准，但由于前向和侧向散射测量的不可靠性，它们在无标记应用中的实用性受到限制。扫描流式细胞仪代表了一种有吸引力的替代方法，因为它利用角度分辨散射光的测量来提供对细胞特性的准确和定量估计，但当前设置的要求不适合与其他芯片实验室技术集成或用于即时护理应用。在这里，我们提出了第一个微流控扫描流式细胞仪（μSFC），能够在标准的聚二甲基硅氧烷微流控芯片内实现准确的角度分辨散射测量。该系统利用低成本的线性可变光密度（OD）滤波器来减小信号的动态范围并提高其信噪比。我们比较了 μSFC 和商用机器在无标记特征化具有不同直径和折射率的聚合物珠方面的性能。与 FCM 和 FACS 相比，μSFC 产生的尺寸估计与标称粒径呈线性相关（ = 0.99），并且可以定量估计颗粒折射率。通过分析基于外周血单核细胞样品形态识别的单核细胞群体，证明了 μSFC 用于生物样品特征化的可行性，得到的结果与文献一致。所提出的 μSFC 结合了低设置要求和高性能，并且在其他芯片实验室系统中用于多参数细胞分析和下一代即时护理诊断应用的集成方面具有巨大潜力。
