Two‐Phase Emulgels for Direct Ink Writing of Skin‐Bearing Architectures

Abstract

Direct ink writing (DIW) provides programmable and customizable platforms to engineer hierarchically organized constructs. However, one-step, facile synthesis of such architectures via DIW has been challenging. This study introduces inks based on two-phase emulgels for direct printing and in situ formation of protecting layers enveloping multicomponent cores, mimicking skin-bearing biological systems. The emulgel consists of a Pickering emulsion with an organic, internal phase containing poly(lactic acid) stabilized by chitin/cellulose nanofibers and a continuous, cross-linkable hydrogel containing cellulose nanofibers and any of the given solid particles. The shear during ink extrusion through nozzles of low surface energy facilitates the generation of the enveloped structures via fast and spontaneous phase separation of the emulgel. The skin-bearing architectures enable control of mass transport as a novel configuration for cargo release. As a demonstration, a hydrophilic molecule is loaded in the hydrogel, which is released through the core and skin, enabling regulation of diffusion and permeation phenomena. This 3D-printed functional material allows independent control of strength owing to the hierarchical construction. The new method of fabrication is proposed as a simple way to achieve protection, regulation, and sensation, taking the example of the functions of skins and cuticles, which are ubiquitous in nature.

Modulation of Physicochemical Characteristics of Pickering Emulsions: Utilization of Nanocellulose- and Nanochitin-Coated Lipid Droplet Blends

“…The average width of this nanocellulose was recently reported to be ∼20 ± 8 nm. 33 The mean particle diameter measured by static light scattering was found to be 18.6 ± 1.2 µm. It should be noted that the mathematical model used to analyze the diffraction pattern in the light scattering instrument assumes that the particles are spherical, and so this value should be treated with caution.…”

Nanocellulose: From Fundamentals to Advanced Applications

“…In contrast, NCs with covalent surface modifications or through the adsorption of surfactants could hydrophobize its surface (contact angle, θ > 90Â • ), consequently stabilize foams or inverse and multiple emulsions. Many pioneering applications already employ nanocellulose-stabilized colloids, for instance, preparation of 3D-printing inks (Huan et al, 2018(Huan et al, , 2019, novel bio-nanocomposites (Reid et al, 2019;Bielejewska and Hertmanowski, 2020), and in gastric stable delivery systems (Bai et al, 2019;Liu and Kong, 2019), pertaining to NCs' outstanding stability and biocompatible nature. Xiang et al discovered that cellulose nanofibrils form more stable foams compared to cellulose nanocrystals, attributed to cellulose nanofibrils ability to spread into the bulk, ensuing enhanced interfacial and bulk elasticity (Xiang et al, 2019).…”

High Internal Phase Oil-in-Water Pickering Emulsions Stabilized by Chitin Nanofibrils: 3D Structuring and Solid Foam

“…30 Pa, which is within the range needed for extrusion-based 3D printing ( Figure S9 ). 59 As shown in Figure 6 b and Video S1 , different letters bearing round structures (“o” and “a”), straight lines (“l” and “t”), and high curvatures (“a”, “t”, and “A”) were printed with high fidelity. In the meantime, different infill densities in the letters were adjusted (see “A” and “t” in Figure 6 b), showing the tuneability of HIPPE ink.…”