Multifunctional Picoliter Droplet Manipulation Platform and Its Application in Single Cell Analysis

• Published in: Analytical chemistry (Washington) Vol. 83; no. 19; pp. 7570 - 7576
• Main Authors: Gu, Shu-Qing, Zhang, Yun-Xia, Zhu, Ying, Du, Wen-Bin, Yao, Bo, Fang, Qun
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.10.2011
• Subjects: Actins - analysis; Actins - genetics; Analytical chemistry; Animals; beta-Galactosidase - chemistry; beta-Galactosidase - metabolism; Cell Line, Tumor; Cells; Chemistry; Deoxyribonucleic acid; DNA; DNA - genetics; DNA - isolation & purification; Enzyme kinetics; Exact sciences and technology; Humans; Microfluidic Analytical Techniques - methods; PC12 Cells; Polymerase Chain Reaction; Rats; Solid Phase Extraction - methods; Encapsulation; Solid phase extraction; Automation; Chemical analysis; Purification; Device; Method; Droplet; Chemical enrichment; Automatic processing; Enzymatic activity; Magnetic separation; Efficiency; DNA; Phase separation; Reagents; Technique; Application; Interface
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac201678g

We developed an automated and multifunctional microfluidic platform based on DropLab to perform flexible generation and complex manipulations of picoliter-scale droplets. Multiple manipulations including precise droplet generation, sequential reagent merging, and multistep solid-phase extraction for picoliter-scale droplets could be achieved in the present platform. The system precision in generating picoliter-scale droplets was significantly improved by minimizing the thermo-induced fluctuation of flow rate. A novel droplet fusion technique based on the difference of droplet interfacial tensions was developed without the need of special microchannel networks or external devices. It enabled sequential addition of reagents to droplets on demand for multistep reactions. We also developed an effective picoliter-scale droplet splitting technique with magnetic actuation. The difficulty in phase separation of magnetic beads from picoliter-scale droplets due to the high interfacial tension was overcome using ferromagnetic particles to carry the magnetic beads to pass through the phase interface. With this technique, multistep solid-phase extraction was achieved among picoliter-scale droplets. The present platform had the ability to perform complex multistep manipulations to picoliter-scale droplets, which is particularly required for single cell analysis. Its utility and potentials in single cell analysis were preliminarily demonstrated in achieving high-efficiency single-cell encapsulation, enzyme activity assay at the single cell level, and especially, single cell DNA purification based on solid-phase extraction.