Dual-Grafting of Microcrystalline Cellulose by Tea Polyphenols and Cationic ε-Polylysine to Tailor a Structured Antimicrobial Soy-Based Emulsion for 3D Printing

Endogenous reactive oxygen species (ROS)-driven protein oxidation regulates emulsifying and foaming properties of liquid egg white

Highly oxidative reactive oxygen species (ROS) attack protein structure and regulate its functional properties. The molecular structures and functional characteristics of egg white (EW) protein (EWP) during 28 d of aerobic or anaerobic storage were explored to investigate the "self-driven" oxidation mechanism of liquid EW mediated by endogenous ROS signaling. Results revealed a significant increase in turbidity during the storage process, accompanied by protein crosslinking aggregation. The ROS yield initially increased and then decreased, leading to a substantial increase in carbonyl groups and tyrosine content. The free sulfhydryl groups and molecular flexibility in EWP exhibited synchronicity with ROS production, reflecting the self-repairing ability of cysteine residues in EWP. Fourier-transform infrared spectroscopy indicated stable crosslinking between EWP molecules in the early oxidation stage. However, continuous ROS attacks accelerated EWP degradation. Compared with the control group, the aerobic-stimulated EWP showed a significant decrease in foaming capacity from 30.5 % to 9.6 %, whereas the anaerobic-stimulated EWP maintained normal levels. The emulsification performance exhibited an increasing-then-decreasing trend. In conclusion, ROS acted as the predominant factor causing deterioration of liquid EW, triggering moderate oxidation that enhanced the superior foaming and emulsifying properties of EWP, and excessive oxidation diminished the functional characteristics by affecting the molecular structure.

A smart thermoresponsive macroporous 4D structure by 4D printing of Pickering-high internal phase emulsions stabilized by plasma-functionalized starch nanomaterials for a possible delivery system

Hierarchically porous structures combine microporosity, mesoporosity, and microporosity to enhance pore accessibility and transport, which are crucial to develop high performance materials for biofabrication, food, and pharmaceutical applications. This work aimed to develop a 4D-printed smart hierarchical macroporous structure through 3D printing of Pickering-type high internal phase emulsions (Pickering-HIPEs). The key was the utilization of surface-active (hydroxybutylated) starch nanomaterials, including starch nanocrystals (SNCs) (from waxy maize starch through acid hydrolysis) or starch nanoparticles (SNPs) (obtained through an ultrasound treatment). An innovative procedure to fabricate the functionalized starch nanomaterials was accomplished by grafting 1,2-butene oxide using a cold plasma technique to enhance their surface hydrophobicity, improving their aggregation, and thus attaining a colloidally stabilized Pickering-HIPEs with a low concentration of each surface-active starch nanomaterial. A flocculation of droplets in Pickering-HIPEs was developed after the addition of modified SNCs or SNPs, leading to the formation of a gel-like structure. The 3D printing of these Pickering-HIPEs developed a highly interconnected large pore structure, possessing a self-assembly property with thermoresponsive behavior. As a potential drug delivery system, this thermoresponsive macroporous 3D structure offered a lower critical solution temperature (LCST)-type phase transition at body temperature, which can be used in the field of smart releasing of bioactive compounds.

Surface Modification of Okara Cellulose Crystals with Phenolic Acids to Prepare Multifunction Emulsifier with Antioxidant Capacity and Lipolysis Retardation Effect

Emulsion-based foods are widely consumed, and their characteristics involving colloidal and oxidative stabilities should be considered. The fabrication of the interfaces by selecting the emulsifier may improve stability and trigger lipolysis, thereby reducing energy uptake from the emulsified food. The present work aimed to develop Okara cellulose crystals (OCs) as a multifunction emulsifier to preserve the physical and chemical stability of a Pickering emulsion via surface modification with phenolic acids. The modification of OC was performed by grafting with the selected phenolics to produce OC-gallic acid (OC-G) and OC-tannic acid (OC-T) complexes. There was a higher phenolic loading efficiency when the OC reacted with gallic acid (ca. 70%) than with tannic acid (ca. 50%). This trend was concomitant with better antioxidant activity of the OC-G than OC-T. Surface modification based on grafting with phenolic acids improved capability of the OC to enhance both the colloidal and oxidative stability of the emulsion. In addition, the cellulosic materials had a retardation effect on the in vitro lipolysis compared to a protein-stabilized emulsion. Surface modification by grafting with phenolic acids successfully provided OC as an innovative emulsifier to promote physico-chemical stability and lower lipolysis of the emulsion.

3D Printing of Bioactive Gel-like Double Emulsion into a Biocompatible Hierarchical Macroporous Self-Lubricating Scaffold for 3D Cell Culture

The interconnected hierarchically porous structures are of key importance for potential applications as substrates for drug delivery, cell culture, and bioscaffolds, ensuring cell adhesion and sufficient diffusion of metabolites and nutrients. Here, encapsulation of a vitamin C-loaded gel-like double emulsion using a hydrophobic emulsifier and soy particles was performed to develop a bioactive bioink for 3D printing of highly porous scaffolds with enhanced cell biocompatibility. The produced double emulsions suggested a mechanical strength with the range of elastic moduli of soft tissues possessing a thixotropic feature and recoverable matrix. The outstanding flow behavior and viscoelasticity broaden the potential of gel-like double emulsion to engineer 3D scaffolds, in which 3D constructs showed a high level of porosity and excellent shape fidelity with antiwearing and self-lubricating properties. Investigation of cell viability and proliferation using fibroblasts (NIH-3T3) within vitamin C-loaded gel-like bioinks revealed that printed 3D scaffolds offered brilliant biocompatibility and cell adhesion. Compared to scaffolds without encapsulated vitamin C, 3D scaffolds containing vitamin C showed higher cell viability after 1 week of cell proliferation. This work represented a systematic investigation of hierarchical self-assembly in double emulsions and offered insights into mechanisms that control microstructure within supramolecular structures, which could be instructive for the design of advanced functional tissues.

High internal phase Pickering emulsions stabilized by ε-poly-l-lysine grafted cellulose nanofiber for extrusion 3D printing

An effective method for preparing food-grade three-dimensional (3D) printing materials was the use of highly concentrated oil-in-water emulsions. This research reported 3D printable materials constructed from food-grade high internal phase Pickering emulsions (HIPPEs) that were stabilized by ε-poly-l-lysine grafted cellulose nanofiber (ε-PL-TOCNs). The ε-PL-TOCNs were prepared via ε-poly-l-lysine grafting of 2, 2, 6, 6-tetramethylpiperidine-N-oxyl (TEMPO)-oxidized cellulose (TOC) and the successive mechanical treatment. Subsequently, the chemical structure, microstructure and surface properties of ε-PL-TOCNs were characterized. The results showed that the prepared ε-PL-TOCNs had excellent dispersion performances, cationic properties brought by amino groups, and hydrophilic/hydrophobic functions of chain structure, which confirmed the feasibility of preparing HIPPEs. The HIPPEs with an internal phase volume fraction of 82 % were obtained at 0.8 wt% ε-PL-TOCNs concentration and pre-emulsification followed by continuous oil feeding. The HIPPEs' storage stability, morphology, and rheological behavior were further discussed. The ultra stable HIPPEs with apparent shear-thinning behavior and high solid viscoelasticity were successful produced, which was suitable for 3D printing. This work expanded the application of nanocellulose in emulsions field and provided a new thinking to prepare food-grade 3D printable materials and porous foam.

Self-assembled emulsion gel based on modified chitosan and gelatin: Anti-inflammatory and improving cellular uptake of lipid-soluble actives

To obtain a green carrier for intestinal targeted delivery, an emulsion gel was designed by the self-assembly between gelatin and Pickering emulsion based on gallic acid modified-chitosan nanoparticles (GCS NPs). The emulsion gels loaded with garlic essential oil (Geo) and curcumin (Cur) were abbreviated as GOEG and GCEG, respectively. Meanwhile, the sodium alginate bead loaded with Geo (GOEGS₃) and the bead loaded with Cur (GCEGS) were prepared as controls. Results demonstrated that the emulsion gels significantly improved the bioaccessibility of Geo and Cur, showing great intestinal targeting delivery properties comparable to that of sodium alginate beads. Moreover, Caco-2 cell experiments indicated that GOEG and GCEG displayed good biocompatibility and enhanced cellular uptake of Geo and Cur. The emulsion gels also exhibited excellent anti-inflammatory properties in the lipopolysaccharide-induced cell model, exhibiting great potential for clinical application. This work provides some references for the preparation of multifunctional emulsion gels with excellent delivery performance by a green method.

Thermomechanically micronized sugar beet pulp: Emulsification performance and the contribution of soluble elements and insoluble fibrous particles

In this work, thermomechanically micronized sugar beet pulp (MSBP), a micron-scaled plant-based byproduct comprised of soluble elements (∼40 wt%) and insoluble fibrous particles (IFPs, ∼60 wt%), was used as a sole stabilizer for oil-in-water emulsion fabrication. The influence of emulsification parameters on the emulsifying properties of MSBP was investigated, including emulsification techniques, MSBP concentration, and oil weight fraction. High-speed shearing (M1), ultrasonication (M2), and microfludization (M3) were used to fabricate oil-in-water emulsions (20% oil) with 0.60 wt% MSBP as stabilizer, in which the d_4,3 value was 68.3, 31.5, and 18.2 μm, respectively. Emulsions fabricated by M2 and M3 (higher energy input) were more stable than M1 (lower energy input) during long-term storage (30 days) as no significant increase of d_4,3. As compared to M1, the adsorption ratio of IFPs and protein was increased from ∼0.46 and ∼0.34 to ∼0.88 and ∼0.55 by M3. Fabricated by M3, the creaming behavior of emulsions was completely inhibited with 1.00 wt% MSBP (20% oil) and 40% oil (0.60 wt% MSBP), showing a flocculated state and could be disturbed by sodium dodecyl sulfate. The gel-like network formed by IFPs could be strengthened after storage as both viscosity and module were significantly increased. During emulsification, the co-stabilization effect of the soluble elements and IFPs enabled a compact and hybrid coverage onto the droplet surface, which acted as a physical barrier to endow the emulsion with robust steric repulsion. Altogether, these findings suggested the feasibility of using plant-based byproducts as oil-in-water emulsion stabilizers.

Insights into the Supramolecular Structure and Degradation Mechanisms of Starch from Different Botanical Sources as Affected by Extrusion-based 3D Printing

Extrusion-based 3D printing has emerged as the most versatile additive manufacturing technique for the printing of practically any material. However, 3D printing of functional materials often activates thermo-mechanical degradation, which affects the 3D shape quality. Herein, we describe the structural changes of eight different starch sources (normal or waxy) as a consequence of the temperature of an extrusion-based 3D printing system through in-depth characterization of their molecular and structural changes. The combination of size-exclusion chromatography, small-angle X-ray scattering, X-ray diffraction, dynamic viscoelasticity measurements, and in vitro digestion has offered an extensive picture of the structural and biological transformations of starch varieties. Depending on the 3D printing conditions, either gelatinization was attained ("moderate" condition) or single-amylose helix formation was induced ("extreme" condition). The stiff amylopectin crystallites in starch granules were more susceptible to thermo-mechanical degradation compared to flexible amorphous amylose. The crystalline morphology of the starch varieties varied from B-type crystallinity for the starch 3D printing at the "moderate" condition to a mixture of C- and V-type crystallinity regarding the "extreme" condition. The "extreme" condition reduced the viscoelasticity of 3D-printed starches but increased the starch digestibility rate/extent. In contrast, the "moderate" condition increased the viscoelastic moduli, decreasing the starch digestion rate/extent. This was more considerable mainly regarding the waxy starch varieties. Finally, normal starch varieties presented a well-defined shape fidelity, being able to form a stable structure, whereas waxy starches exhibited a non-well-defined structure and were not able to maintain their integrity after printing. The results of this research allow us to monitor the degradability of a variety of starch cultivars to create starch-based 3D structures, in which the local structure can be controlled based on the 3D printing parameters.