Drop-based microfluidic devices for encapsulation of single cells

Abstract

We use microfluidic devices to encapsulate, incubate, and manipulate individual cells in picoliter aqueous drops in a carrier fluid at rates of up to several hundred Hz. We use a modular approach with individual devices for each function, thereby significantly increasing the robustness of our system and making it highly flexible and adaptable to a variety of cell-based assays. The small volumes of the drops enables the concentrations of secreted molecules to rapidly attain detectable levels. We show that single hybridoma cells in 33 pL drops secrete detectable concentrations of antibodies in only 6 h and remain fully viable. These devices hold the promise of developing microfluidic cell cytometers and cell sorters with much greater functionality, allowing assays to be performed on individual cells in their own microenvironment prior to analysis and sorting.

Encapsulation of single cells into monodisperse droplets by fluorescence-activated droplet formation on a microfluidic chip

“…Results indicated an average occupancy of 94.3% for droplets containing one bead. Further application to individual HeLa cells showed 82.5% occupancy of droplets by single cells, which is about 3 fold higher than those obtained by random compartmentalization [28,29]. The developed method provides an effective means for on-command generation of droplets and encapsulation of single cells on microfluidic chips.…”

“…Both methods have been proven effective in encapsulating cells. However, the compartmentalization of cells in droplets is a random process dictated by Poisson statistics, yielding a majority of empty droplets and droplets containing multiple cells [28,29].…”

Microfluidic devices fabricated using fast wafer-scale LED-lithography patterning

“…The first side of a two-layer 3D flow focusing device is in nature very similar to devices that have been previously used to produce double emulsion droplets. 13 The micrograph (Figs. 6(c) and 6(d)) shows that the thin (20 lm wide, 25 lm high) channel is well positioned with respect to the thick channels (50 lm wide, 50 lm high).…”

“…The treatment improved the wetting of the channels with fluorinated oil. 13 Ethanol and water solutions were mixed on the chip to form a solution of 10% (v/v) ethanol in water, and microdroplets were formed in an oil phase of Fluorinert FC-40 (Sigma-Aldrich) and 2.0% (w/w) block-copolymer surfactant. Such a two component mixer on chip devices has been previously used to study peptide self-assembly.…”

Controlled Synthesis of Cell-Laden Microgels by Radical-Free Gelation in Droplet Microfluidics

“…An advantage of the use of prefabricated macromolecular precursors for the microgel synthesis is that it allows a systematic variation of the macromonomer properties, providing more insight into the relation between the microgel properties and the viabilities of encapsulated cells. As a future perspective, further refinement of the cell-laden microgel fabrication could be achieved by combining droplet-based microfluidic methods for single cell encapsulation 56 with subsequent fluorescence-activated sorting 57 to separate microgels containing living cells from microgels containing dead cells. …”