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Epifluorescence image of a water-in-water Pickering emulsion (green latex beads) with core gelation to form colloidosomes (left). Confocal microscopy image showing sequestration of a fluorescent polymer in red by colloidosomes (right)

A new technique to encapsulate biomolecules

Scientists from INRA, CNRS and Université de Bordeaux have managed to develop a new technique that enables the production of microparticles that can spontaneously store biomolecules (colloidosomes). For the first time, they have designed such an encapsulation system in water, without using either solvent or oil. Published in Angewandte Chemie International Edition on 25 June 2018, these findings open perspectives for the development of new types of capsules containing active substances, and more generally for the creation of artificial cells.

Updated on 07/30/2018
Published on 06/25/2018

The formulation of compartments (or capsules) that can encapsulate biological materials (proteins, enzymes, DNA, etc.) is of considerable interest not only from an industrial point of view but fundamentally regarding the development of artificial cells. The best known compartments, liposomes, form from lipids and are notably used for cosmetic purposes. Other compartments are based on ‘colloidal’1 particles, and are thus called ‘colloidosomes’.

Until now, these colloidosomes were produced by adding particles (such as latex or silica, etc.) to oil/water emulsions (Figure 1) to form so-called ‘Pickering’ emulsions (from the name of the British scientist who discovered this phenomenon in the early 20th century). These particles are then linked chemically to form robust capsules that can be transferred to water. However, use of the solvents and oil necessary for their manufacture constitutes an obstacle to their development, because the active substances need to be added at the start of manufacture and may therefore be destroyed by the solvents.

      

Diagram of a droplet of oil/water emulsion, the addition of particles (yellow circles) leads to the formation of a Pickering emulsion (centre), the particles are then linked chemically to form colloidosomes (right). © INRA
Diagram of a droplet of oil/water emulsion, the addition of particles (yellow circles) leads to the formation of a Pickering emulsion (centre), the particles are then linked chemically to form colloidosomes (right) © INRA

   

A new oil- and solvent-free system

For the first time, scientists from INRA, CNRS and Université de Bordeaux, working in collaboration with a team from University of Bristol (UK) have developed a novel method to produce these colloidosomes directly in water using neither solvent nor oil. Their approach is based on so-called ‘water-in-water’ emulsions that form notably in mixtures of ‘incompatible’ polymers. In this system, polymer-enriched droplets are dispersed in a medium enriched in another polymer. The scientists were able to show that latex particles moved to the interface between droplets and thus formed water-in-water Pickering emulsions (Figure 2).  They then succeeded in gelling the interior of these droplets, thus forming colloidosomes directly in the aqueous phase. The advantage of these systems is that they are known to spontaneously ‘sequestrate’ biological material and active substances within the droplets. The scientists thus revealed that these colloidosomes could indeed spontaneously sequestrate fluorescent entities. Their findings open the way towards future studies on the encapsulation of biological materials and active substances in new types of capsules. In the years to come, these results may enable the development of colloidosome-type capsules in the context of creating artificial cells.

      

Epifluorescence image of a water-in-water Pickering emulsion (green latex beads) with core gelation to form colloidosomes (left). Confocal microscopy image showing sequestration of a fluorescent polymer in red by colloidosomes (right)
Epifluorescence image of a water-in-water Pickering emulsion (green latex beads) with core gelation to form colloidosomes (left). Confocal microscopy image showing sequestration of a fluorescent polymer in red by colloidosomes (right)

    

1 Small particles in suspension in a liquid.

Contact(s)
Scientific contact(s):

Press Relations:
INRA News Office (33 1 42 75 91 86)
Associated Division(s):
Plant Health and Environment
Associated Centre(s):
Nouvelle-Aquitaine-Bordeaux

Reference

Preparation of swellable hydrogel-containing colloidosomes from aqueous two-phase Pickering emulsion droplets. Jean-Paul Douliez, Nicolas Martin, Thomas Beneyton, Jean-Charles Eloi, Jean-Paul Chapel, Laurence Navailles, Jean-Christophe Baret, Stephen Mann and Laure Béven. Angewandte Chemie International Edition, 57 (2018) 7780-7784.