Single‐Cell Analysis Using Droplet Microfluidics

Abstract

Droplet microfluidics has revolutionized the study of single cells. The ability to compartmentalize cells within picoliter droplets in microfluidic devices has opened up a wide range of strategies to extract information at the genomic, transcriptomic, proteomic, or metabolomic level from large numbers of individual cells. Studying the different molecular landscapes at single‐cell resolution has provided the authors with a detailed picture of intracellular heterogeneity and the resulting changes in cellular phenotypes. In addition, these technologies have aided in the discovery of rare cells in tumors or in the immune system, and left the authors with a deeper understanding of the fundamental biological processes that determine cell fate. This review aims to provide a detailed overview of the various droplet microfluidic strategies reported in the literature, taking into account the sometimes subtle differences in workflow or reagents that enable or improve certain protocols. Specifically, approaches to targeted‐ and whole‐genome analysis, as well as whole‐transcriptome profiling techniques, are reviewed. In addition, an up‐to‐date overview of new methods to characterize and quantify single‐cell protein levels, and of developments to screen secreted molecules such as antibodies, cytokines, or metabolites at the single‐cell level, is provided.

Review of Microfluidic Methods for Cellular Lysis

“…The platform encapsulated cells into droplets filled with lysis buffer. Similar droplet-based microfluidic devices, utilizing chemical lysis detergents are described in [34][35][36]. [33] encapsulates cells into droplets with lysis buffer for cell lysis.…”

Microfluidic formation of crystal-like structures

“…116 In this section, we review some of the most recent advances in microfluidic crystals and compartmentalisation, citing also some pioneering works in the field. A broader overview of the applications related to microfluidic compartmentalisation (not only crystals) can be found in the following recent reviews: encapsulation, 117 singlecell analysis, 118 multiple emulsions, 119,120 self-assembly, 121 and production of biomaterials. 122…”

Inertial Microfluidics Enabling Clinical Research

“…Microfluidic RBC lysis devices can be positioned upstream of other microfluidic tasks, such as CTC isolation or cell stretching [53,[100][101][102][103], that require sample preprocessing. Similarly, future studies can build on the integration of target isolation and droplet generation for single-cell analysis [208]. The further development of hybrid devices will improve microfluidic device performance and enable new capabilities.…”