Improved synthesis of microcapsules for synthetic biology

A microfluidic approach shows great improvement over traditional methods

A new microfluidics-based system for making proteinosomes, special cell-like capsules that show high promise in both medicine and basic research, has been developed by Martina Ugrinic and coworkers. The approach yields proteinosomes that are of much higher quality than those made by traditional bulk methods, with narrower size distributions and enhanced cargo-carrying capabilities.

Proteinosomes are microscopic particles with a shell consisting of chemically-modified proteins. They possess two key attributes. Firstly, they can carry molecular cargo, an ability with many applications including targeted drug delivery and encapsulation of biochemical reactions in confined ‘cell-like’ environments for artificial life studies. Secondly, as the shell is composed of proteins, it can be biologically active itself, for example using enzymes to make proteinosomes yields catalytically active microcapsules. Together, these attributes make proteinosomes very versatile and highly promising tools in biological research.

Martina Urgrinic of the deMello group, and coworkers at the Max Planck Institute of Molecular Cell Biology and Genetics, used a custom-designed microfluidic chip to achieve precise control over the formation of proteinosomes. The key success of the work was to show that the microfluidic approach could achieve a product that is superior to bulk emulsification methods. The traditional bulk method relies upon the natural formation of an emulsion in a water-in-oil system, with the size of the emulsion droplets showing an inherently large size distribution. In contrast, the microfluidic approach incorporates a microscale nozzle that can rapidly produce droplets of a consistent size, one at a time. Further, the size of the droplets can be directly controlled by changing the size of the nozzle and the flow rate of the precursors. The new system was used to produce water-in-oil emulsions, and these could be converted to water-in-water type particle dispersions by a post-processing step.

The team demonstrated the functionality of the proteinosomes by encapsulating horseradish peroxidase enzymes inside glucose peroxidase enzyme proteinosomes, then showing that both enzymes retained excellent catalytic efficiency after proteinosome formation. Such a system shows the promise of the microfluidic synthesis of proteinosomes, and the team hopes that their novel approach will pave the way for more advanced syntheses and applications in the near future.

Written by Philip Howes.

Read the full paper here.

The microfluidic chip can rapidly and controllably make droplets that form the proteinosomes

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