Droplet Microfluidic Technology For Automatic Sorting At The Single Cell Level

The recognition of cellular functions at the single cell level can bring breakthroughs to the study of heterogeneity of the biological population,and the sorting of single cell with a specific phenotypes is a premise for the study of the scientific question of “individual heterogeneity and phenotypic diversity of cells”.Droplet microfluidic technology provides powerful support for cell sorting at the single cell level by virtue of its flexible manipulation,high integration,and portability.In this paper,a high-yield astaxanthin Haematococcus pluvialis model is used to focus on the goal which is to automated,high-throughput sorting of its specific algal strains.The main research contents are as follows:(1)Single-cell encapsulation and culture based on droplet microfluidic technology.Microfluidic droplet generation techniques with flow-focusing structure are used to generate single-cell droplets of uniform size.Since the appear of growth phenotypic difference for the microalgae require off-line cultivation for a long time,the use of ultra-low melting agarose has been introduced.The single cells were encapsulated in agarose gel microspheres to avoid the fusion and disruption of the droplets after long time off-line culture.(2)Build an automated droplet sorting platform based on the single cell growth phenotype.The microfluidic chip of droplet sorting integrates a absorbance detection unit for droplet and a droplet sorting unit based on a solenoid valve suction,meanwhile the platform uses a graphical programming language LabVIEW to write a software to realize automatic sorting.Based on this platform,the H.pluvialis strain with high growth rate is sorted out automation.(3)A Raman activated droplet sorting(RADS)platform has been set up,which successfully integrates single cell Raman spectroscopy acquisition with dielectrophoresis sorting droplet microfluidic technology.The microfluidic chip of the RADS platform places the Raman detection unit in front of the droplet generation unit,effectively avoiding the effects of the droplet lens effect and the Raman background of the oil phase on the Raman signal acquisition of the cell,and improving the Raman identification accuracy.Based on this platform,automated and accurate sorting of H.pluvialis with high-yield astaxanthin was realized at the single cell level.