Hydrogel Photopolymerization within Microfluidic Droplets for Single Cell Encapsulation

Abstract

Molecular investigation of specific gene expression patterns at single cell level could reveal the heterogeneity of bulk cell populations, facilitating the understanding of the interactive regulatory pathways that are hidden. However, this understanding has been constrained for decades by length scale differences between traditional macroscopic tools and the size of a single cell. Additionally, these tools are inadequate in working efficacy to manipulate millions of individual cells within a reasonably short time period. Therefore, issues associated with above shortages represent a challenge for single cell encapsulation and subsequent analysis. This review highlights recent development in droplet-microfluidic technique that have enabled high throughput fabrication of cell-laden picoliter droplets, which can be subsequently photopolymerized into microgels for further analytical assessment or bottom-up tissue engineering practices. Novel microfluidic droplet techniques developed for single cell screening, analysis, and scaffold assembly for tissue engineering are introduced.Meanwhile, constraints and challenges encountered with microfluidic droplet miniaturization processing are discussed in the content of enabling single cell manipulation. In the end, emerging alternative material, which holds great promises for single cell encapsulation in miniaturized hydrogels, is introduced as cell carrier with biocompatible polymerization kinetics and cytocompatibility.