Issue 22, 2018

Microfluidic diamagnetic water-in-water droplets: a biocompatible cell encapsulation and manipulation platform

Abstract

Droplet microfluidics enables cellular encapsulation for biomedical applications such as single-cell analysis, which is an important tool used by biologists to study cells on a single-cell level, and understand cellular heterogeneity in cell populations. However, most cell encapsulation strategies in microfluidics rely on random encapsulation processes, resulting in large numbers of empty droplets. Therefore, post-sorting of droplets is necessary to obtain samples of purely cell-encapsulating droplets. With the recent advent of aqueous two-phase systems (ATPS) as a biocompatible alternative of the conventional water-in-oil droplet systems for cellular encapsulation, there has also been a focus on integrating ATPS with droplet microfluidics. In this paper, we describe a new technique that combines ATPS-based water-in-water droplets with diamagnetic manipulation to isolate single-cell encapsulating water-in-water droplets, and achieve a purity of 100% in a single pass. We exploit the selective partitioning of ferrofluid in an ATPS of polyethylene glycol–polypropylene glycol–polyethylene glycol triblock copolymer (PEG–PPG–PEG) and dextran (DEX), to achieve diamagnetic manipulation of water-in-water droplets. A cell-triggered Rayleigh–Plateau instability in the dispersed phase thread results in a size distinction between the cell-encapsulating and empty droplets, enabling diamagnetic separation and sorting of the cell-encapsulating droplets from empty droplets. This is a simple and biocompatible all-aqueous platform for single-cell encapsulation and droplet manipulation, with applications in single-cell analysis.

Graphical abstract: Microfluidic diamagnetic water-in-water droplets: a biocompatible cell encapsulation and manipulation platform

Supplementary files

Article information

Article type
Paper
Submitted
20 Aug. 2018
Accepted
10 Okt. 2018
First published
16 Okt. 2018

Lab Chip, 2018,18, 3361-3370

Microfluidic diamagnetic water-in-water droplets: a biocompatible cell encapsulation and manipulation platform

M. Navi, N. Abbasi, M. Jeyhani, V. Gnyawali and S. S. H. Tsai, Lab Chip, 2018, 18, 3361 DOI: 10.1039/C8LC00867A

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