Recent advances in droplet microfluidics for single-cell analysis

Single-cell manipulation and analysis is essential for studying many fundamental biological processes and discovering cellular heterogeneity. Multi-parameter studies of intercellular biomolecules at the single cell level are now available to improve early diagnosis and personalized treatment of diseases. However, the small size of cells and low concentration of target biomolecules are critical challenges for single-cell analysis. Droplet microfluidics, with the ability to delineate cells in picoliter droplets by microfluidic devices, has revolutionized single-cell studies, providing a wide range of strategies for extracting information at the genomic, transcriptomic, proteomic, and metabolomic level from large numbers of individual cells. Furthermore, studying different molecular landscapes at single-cell resolution gives the researchers a detailed picture of intracellular heterogeneity and the resulting changes in cellular phenotype. In this review, the advances of droplet microfluidics in the single-cell analysis are summarized, especially for the underline of significant advantages, the preparation, and various assays for droplet microfluidics analysis. In addition, its application of single-cell analysis is also highlighted, including whole-genome analysis, whole transcriptome analysis, single-cell protein levels quantification, and the advances in analyst screening such as antibodies, cytokines, or metabolites at the single-cell level. Generally, the application of droplet microfluidics in single-cell analysis can reveal the gene structure and expression status of individual cells, promoting the fundamental and clinical research of tumors, neuroscience, etc.