Pickering and Network Stabilization of Biocompatible Emulsions Using Chitosan-Modified Silica Nanoparticles

Abstract

Edible solid particles constitute an attractive alternative to surfactants as stabilizers of food-grade emulsions for products requiring a long-term shelf life. Here, we report on a new approach to stabilize edible emulsions using silica nanoparticles modified by noncovalently bound chitosan oligomers. Electrostatic modification with chitosan increases the hydrophobicity of the silica nanoparticles and favors their adsorption at the oil-water interface. The interfacial adsorption of the chitosan-modified silica particles enables the preparation of oil-in-water emulsions with small droplet sizes of a few micrometers through high-pressure homogenization. This approach enables the stabilization of food-grade emulsions for more than 3 months. The emulsion structure and stability can be effectively tuned by controlling the extent of chitosan adsorption on the silica particles. Bulk and interfacial rheology are used to highlight the two stabilization mechanisms involved. Low chitosan concentration (1 wt % with respect to silica) leads to the formation of a viscoelastic film of particles adsorbed at the oil-water interface, enabling Pickering stabilization of the emulsion. By contrast, a network of agglomerated particles formed around the droplets is the predominant stabilization mechanism of the emulsions at higher chitosan content (5 wt % with respect to silica). These two pathways against droplet coalescence and coarsening open up different possibilities to engineer the long-term stabilization of emulsions for food applications.

Chitin nanocrystals as Pickering stabilizer for O/W emulsions: Effect of the oil chemical structure on the emulsion properties

“…The gel-like property of the emulsion is indicative of the generation of three-dimensional networks that might result from different mode of interconnection including; droplet-droplet, ChNC-ChNC and ChNC-droplet. In Pickering emulsions, the gel aspect of the emulsion has been widely reported in the literature with different possible origins being proposed, such as droplet-bridging, particle network, and partial aggregation [38,39]. Referring to Figure 4A,B,D, the magnitude of G′ increased with the ChNC content, meaning that the network cohesion increased with the concentration of added ChNCs.…”

Methods for producing microstructured hydrogels for targeted applications in biology

“…6b) [49,[183][184][185]. However, due to their inherent negative surface charge, unmodified particles remain preferentially in the hydrophilic phase, so surface modifications with molecules such as chitosan, betaine, and polyethylene oxide copolymers, among others, have been performed to alter the hydropathy of the nanoparticles and permit their localization at the interface [186][187][188]. Janus particles have also been employed for Pickering emulsions because one half can be formed by a material with affinity to one phase and the other half with affinity to the other phase, allowing them to migrate exactly to the interface.…”

3D printing of sacrificial templates into hierarchical porous materials

“…A freeze-fracture technique was used to prepare samples of nanodroplets for imaging in a cryo-SEM 41,42 . Samples were prepared as explained in our previous work 43 .…”