Li Dongliang, Li Wei, Chen Rong, Zhu Xun, Ye Dingding, Yang Yang, Liao Qiang
Key Laboratory of Low-Grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China.
Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China.
Anal Chem. 2023 Apr 4;95(13):5828-5837. doi: 10.1021/acs.analchem.3c00763. Epub 2023 Mar 24.
Precision manipulation of particle-enrichment patterns in droplets is challenging but important in biochemical analysis and clinical diagnosis. Herein, a light strategy for precisely manipulating particle enrichment patterns is reported. Focused laser irradiation to the droplet induces a Marangoni flow owing to a localized photothermal effect, which carries in-droplet particles and concentrates them at the laser-spot-acted region. Owing to high flexibility of light, multiple particle-enriched sites are formed in a droplet, and the concentrated particles can be transported and reconstructed on demand. In addition to the island-like enrichment pattern, this optical particle manipulation strategy enables the formation of various particle-enriched patterns, such as the line-shape and circle-shape patterns. Further, light directly acts on the working fluid instead of target particles, considerably weakening dependence on particle properties. For particles whose density is similar to that of the working fluid, a portion of particles can still be concentrated. It is also found that only a small portion of submicron particles can be concentrated, while nanoparticles are hardly concentrated by this light strategy. Moreover, high reconfigurability of light enables in-parallel high-throughput operations, which is demonstrated using two laser beams to form two particle enrichment sites in a droplet simultaneously. Finally, this light strategy is also demonstrated by concentrating cells and nucleic acid molecules. This work paves the way for the applications of optofluidics in cell sorting, point-of-care analysis, and drug screening.
在生化分析和临床诊断中，精确操控液滴中的粒子富集模式具有挑战性但却十分重要。在此，我们报道了一种精确操控粒子富集模式的光策略。对液滴进行聚焦激光照射会由于局部光热效应诱导产生马兰戈尼流，该马兰戈尼流会携带液滴内的粒子并将它们集中在激光作用的区域。由于光具有高度灵活性，液滴中会形成多个粒子富集位点，并且可以根据需要对集中的粒子进行运输和重构。除了岛状富集模式外，这种光学粒子操控策略还能形成各种粒子富集模式，如线状和圆形模式。此外，光直接作用于工作流体而非目标粒子，大大减弱了对粒子性质的依赖性。对于密度与工作流体相似的粒子，仍有一部分粒子能够被集中。研究还发现，通过这种光策略只有一小部分亚微米粒子能够被集中，而纳米粒子几乎无法被集中。而且，光的高可重构性能够实现并行高通量操作，利用两束激光在一个液滴中同时形成两个粒子富集位点就证明了这一点。最后，通过对细胞和核酸分子进行集中也证明了这种光策略。这项工作为光流体学在细胞分选、即时检测分析和药物筛选中的应用铺平了道路。
