Automated generation of libraries of nL droplets

Abstract

We demonstrate an integrated system for rapid and automated generation of multiple, chemically distinct populations of ~10(3)-10(4) sub-nanoliter droplets. Generation of these 'libraries of droplets' proceeds in the following automated steps: i) generation of a sequence of micro-liter droplets of individually predetermined composition, ii) injection of these 'parental' droplets onto a chip, iii) transition from a mm- to a μm-scale of the channels and splitting each of the parental drops with a flow-focusing module into thousands of tightly monodisperse daughter drops and iv) separation of such formed homogeneous populations with plugs of a third immiscible fluid. This method is compatible both with aspiration of microliter portions of liquid from a 96-well plate with a robotic station and with automated microfluidic systems that generate (~μL) droplets of preprogrammed compositions. The system that we present bridges the techniques that provide elasticity of protocols executed on microliter droplets with the techniques for high-throughput screening of small (~pL, ~nL) droplet libraries. The method that we describe can be useful in exploiting the synergy between the ability to rapidly screen distinct chemical environments and to perform high-throughput studies of single cells or molecules and in digital droplet PCR systems.

Suzuki–Miyaura cross-coupling optimization enabled by automated feedback

“…For instance, simplified droplet-flow systems are often implemented with reaction droplets suspended in an inert perfluorinated carrier phase, 14,15 which becomes miscible with a majority of commonly used organic solvents at elevated temperatures 16 and can lead to contamination from experiment to experiment with droplet budding and breaking. 17 Polydimethylsiloxane, the favored medium for droplet flow devices, 12,18 swells upon exposure to conventional reagents and solvents. Though UV-vis, 19 fluorescence, 15,20 and IR 21 are all popular analytical methods for demonstrating the speed of droplet screening, these do not achieve the resolution of chromatographic methods when it comes to distinguishing key products and intermediates.…”

Bacterial Growth and Adaptation in Microdroplet Chemostats

“…microliter) droplets containing populations of microorganisms into thousands of monodisperse small (picoliter) droplets [25] for further screening at the single cell level. [22][23][24] This could open new areas of study, including the distribution of fitness or gene expression in a population subject to changes of the chemical envioronement in which it grows.…”

Accelerating bacterial growth detection and antimicrobial susceptibility assessment in integrated picoliter droplet platform

“…As dropFAST is designed to be a universal platform capable of testing any species of bacteria against any type of antibiotic, additional validations using different strains of bacteria against several different antibiotics are also warranted. Considering practical needs in clinical microbiology, several additions to the current dropFAST device may be necessary, including the ability to test multiple combinations of bacteria and antibiotics in the same device while maintaining droplet stability and uniformity (Kaminski et al, 2012), as well as the ability to automate a sample-to-answer workflow by integrating a sample loading system (T. D. Rane et al, 2012; Zec et al, 2012). With a potential to improve functionality and scale, we envision the dropFAST platform becoming a useful clinical tool for accelerating phenotypic assessment of antimicrobial susceptibility.…”