A Microfluidic Droplet Chip For Efficient Single Cell Loading

Cells are the basic structural and functional units of living organisms.There was obvious heterogeneity among cells in morphology,size,growth rate and biomolecular expression.Single cell operation analysis is now being an indispensable strategy for better exploring mysteries of cells,and thus systematically recognizing the functional behavior of tissues,organs,and organisms.The encapsulation of single cells in microscale droplets can not only control the microenvironment of cell growth,but also act as a tool to conduct independent cell monitoring or manipulation,which is critical to explore single cell activities.In combination with a chamber that is independent of microdroplets and the bionic advantages of collagen hydrogel,a microfluidic droplet chip was designed and prepared by using microfluidic droplet technology in this study,which realized efficient single cell loading in microdroplets and microgels.The main research results are as follows:(1)A novel microfluidic chip system was fabricated by soft photolithography using Polydimethylsiloxane(PDMS).Through the optimization of various parameters,the PDMS microfluidic chip was successfully prepared,with good sealing performance,providing a reliable platform for subsequent droplets/microgels preparation and single cell loading.(2)Microdroplets and calcium alginate microgels with good monodispersity were successfully produced by using the as-prepared microfluidic chip.The size of the droplets and microgels can be modified by precisely adjusting the fluid flow rate,which laid a technical foundation for the subsequent single cell encapsulation experiment.(3)Single cell droplets and single cell collagen microgels were produced successively based on microfluidic droplet chip.Through cell density optimization,efficient single cell loading(single cell encapsulation rate reached 33.56%)was realized in the chip,which provided a reliable research platform for tissue biomimetic single cell analysis in the future.In summary,this study provides a methodological strategy for the producing single cell droplets and bionic microgels,which has a wide application prospect in biomedical research fields of drug screening,cell proliferation,and tumor stem cell screening at the single-cell level.