Summary It has long been the dream of biologists to map gene expression at the single cell level. With such data one might track heterogeneous cell sub-populations, and infer regulatory relationships between genes and pathways. Recently, RNA sequencing has achieved single cell resolution. What is limiting is an effective way to routinely isolate and process large numbers of individual cells for quantitative in-depth sequencing. We have developed a high-throughput droplet-microfluidic approach for barcoding the RNA from thousands of individual cells for subsequent analysis by next-generation sequencing. The method shows a surprisingly low noise profile and is readily adaptable to other sequencing-based assays. We analyzed mouse embryonic stem cells, revealing in detail the population structure and the heterogeneous onset of differentiation after LIF withdrawal. The reproducibility of these high-throughput single cell data allowed us to deconstruct cell populations and infer gene expression relationships.

Emulsions stabilized through the adsorption of colloidal particles at the liquid-liquid interface have long been used and investigated in a number of different applications. The interfacial adsorption of particles can be induced by adjusting the particle wetting behavior in the liquid media. Here, we report a new approach to prepare stable oil-in-water emulsions by tailoring the wetting behavior of colloidal particles in water using short amphiphilic molecules. We illustrate the method using hydrophilic metal oxide particles initially dispersed in the aqueous phase. The wettability of such particles in water is reduced by an in situ surface hydrophobization that induces particle adsorption at oil-water interfaces. We evaluate the conditions required for particle adsorption at the liquid-liquid interface and discuss the effect of the emulsion initial composition on the final microstructure of oil-water mixtures containing high concentrations of alumina particles modified with short carboxylic acids. This new approach for emulsion preparation can be easily applied to a variety of other metal oxide particles.

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Macroporous ceramics are fabricated using emulsions stabilized with particles of various chemical compositions. Stabilization with particles hinders extensive droplet coalescence during solvent extraction, allowing for drying and sintering of the emulsions directly into macroporous materials in the absence of any chemical reaction.

Semipermeable, hollow capsules are attractive materials for the encapsulation and delivery of active agents in food processing, pharmaceutical and agricultural industries, and biomedicine. These capsules can be produced by forming a solid shell of close packed colloidal particles, typically polymeric particles, at the surface of emulsion droplets. However, current methods to prepare such capsules may involve multistep chemical procedures to tailor the surface chemistry of particles or are limited to particles that exhibit inherently the right hydrophobic-hydrophilic balance to adsorb around emulsion droplets. In this work, we describe a general and simple method to fabricate semipermeable, inorganic capsules from emulsion droplets stabilized by a wide variety of colloidal metal oxide particles. The assembly of particles at the oil-water interface is induced by the in situ hydrophobization of the particle surface through the adsorption of short amphiphilic molecules. The adsorption of particles at the interface leads to stable capsules comprising a single layer of particles in the outer shell. Such capsules can be used in the wet state or can be further processed into dry capsules. The permeability of the capsules can be modified by filling the interstices between the shell particles with polymeric or inorganic species. Functional capsules with biocompatible, bioresorbable, heat-resistant, chemical-resistant, and magnetic properties were prepared using alumina, silica, iron oxide, or tricalcium phosphate as particles in the shell.