Monodisperse drops templated by 3D-structured microparticles

Abstract

The ability to create uniform subnanoliter compartments using microfluidic control has enabled new approaches for analysis of single cells and molecules. However, specialized instruments or expertise has been required, slowing the adoption of these cutting-edge applications. Here, we show that three dimensional–structured microparticles with sculpted surface chemistries template uniformly sized aqueous drops when simply mixed with two immiscible fluid phases. In contrast to traditional emulsions, particle-templated drops of a controlled volume occupy a minimum in the interfacial energy of the system, such that a stable monodisperse state results with simple and reproducible formation conditions. We describe techniques to manufacture microscale drop-carrier particles and show that emulsions created with these particles prevent molecular exchange, concentrating reactions within the drops, laying a foundation for sensitive compartmentalized molecular and cell-based assays with minimal instrumentation.

Single-Cell Phenotypic Analysis and Digital Molecular Detection Linkable by a Hydrogel Bead-Based Platform

“…We note that interfacial leakage of the metabolized dye molecules might also have reduced the fluorescence intensity difference between bright and dark Gelbeads for incubation below 5 h. These observations indicate that the optimization of incubation time is a race between cross-talking and cell proliferation. The incorporation of PEG hydrogel into aqueous phase likely has already enhanced the retention of the resorufin-based dye due to its preferred partition in the PEG layer, as illustrated in the dropicle system developed by Wu et al 34 The leakage can be further reduced by changing to another specific type of oil phase, indicator dye molecule, or surfactant. 35 Considering the intrinsic difference in proliferation rate between bacterial species, the observed incubation time for distinction of positive and negative compartments was comparable to the results by Lyu et al, who achieved Escherichia coli ( E. coli ) phenotyping with alamarBlue in 85 pL droplets with a 2 h incubation.…”

Massively parallel encapsulation of single cells with structured microparticles and secretion-based flow sorting

“…Spherical gel particles have been used previously to template emulsions (28,29), however, the lack of a cavity precluded their use with mammalian cells, and no secretion assays or compatibility with flow cytometry were demonstrated. We have also previously used amphiphilic cavity-containing particles to form uniform emulsions and perform molecular and cellular assays (25)(26)(27); however, these previous systems were not compatible with commercial flow cytometers due to their hydrophobic components.…”

“…Nanovials can be analyzed and isolated using commonly available FACS instruments enabling screening at rates >1000 events per second. While other particle systems have been utilized to hold sub-nanoliter volumes (25)(26)(27)(28)(29), ours is the first approach that allows attachment and protection of cells in cavities within particles, unlocking new capabilities to expand the scale of analysis by integration with flow cytometry. Using this easily-adopted nanovial format we conducted a screen of over 1 million events in less than an hour using a commercial FACS instrument, sorting out rare antibody-secreting cells from orders of magnitude more abundant background cells, all within one day.…”

Deformable and Robust Core–Shell Protein Microcapsules Templated by Liquid–Liquid Phase‐Separated Microdroplets

“…This can be used for personalized medicine, nanoparticle-based therapies, and artificial tissue scaffolds as asynchronous drug carriers for short-term and long-term releases in vivo or in vitro. [82,83]…”