One-Step Generation of O/W/O Double Pickering Emulsions Utilizing Biocompatible Gliadin/Ethyl Cellulose Complex Particles as the Exclusive Stabilizer.

Double emulsions hold great potential for various applications due to their compartmentalized internal structures. However, achieving their long-term physical stability remains a challenging task. Here, we present a simple one-step method for producing stable oil-in-water-in-oil (O/W/O) double emulsions using biocompatible gliadin/ethyl cellulose complex particles as the sole stabilizer. The resulting O/W/O systems serve as effective platforms for encapsulating enzymes and as templates for synthesizing porous microspheres. We investigated the impact of particle concentration and water fraction on the properties of Pickering O/W/O emulsions. Our results demonstrate that the number and volume of inner oil droplets increased proportionally with both the water fraction and particle concentration after a 60-day storage period. Moreover, the catalytic reaction rate of the encapsulated lipase within the double emulsion exhibited a significant acceleration, achieving a substrate conversion of 80.9% within 15 min. Remarkably, the encapsulated enzyme showed excellent recyclability, enabling up to 10 cycles of reuse. Additionally, by utilizing the O/W/O systems as templates, we successfully obtained porous microspheres whose size can be controlled by the outer water droplet. These findings have significant implications for the future design of Pickering complex emulsion-based systems, opening avenues for extensive applications in pharmaceuticals, food, cosmetics, material synthesis, and (bio)catalysis.

Biocompatible gliadin-sericin complex colloidal particles used for topical delivery of the antioxidant phloretin.

Oxidative stress caused by environmental exposures results in numerous skin diseases. Phloretin (PHL) is often used to relieve various skin symptoms, however, precipitation or crystallization of PHL in aqueous systems limits its ability to diffuse through the stratum corneum, making it difficult to exert effect at the target. To address this challenge, we herein report a method for the generation of core-shell nanostructure (G-LSS) via the growth of sericin crust around gliadin nanoparticle as a topical nanocarrier of PHL to improve its cutaneous bioavailability. Physicochemical performance, morphology, stability, and antioxidant activity of the nanoparticles were characterized. G-LSS-PHL exhibited uniformed spherical nanostructures with the robust encapsulation on PHL (∼90 %). This strategy protected PHL from UV-induced degradation, facilitating to inhibit erythrocyte hemolysis and quench free radicals in a dose-dependent manner. Transdermal delivery experiments and porcine skin fluorescence imaging indicated that G-LSS facilitated the penetration of PHL across the epidermis layer of skin to reach deep-seated sites, and promoted cumulative turnover of PHL with a 2.0-fold increase. Cell cytotoxicity and uptake assay confirmed that as-prepared nanostructure was nontoxic to HSFs, and promoted cellular absorption of PHL. Therefore, this work opened up new promising avenues for developing robust antioxidant nanostructure for topical applications.

Bioavailability of quercetin in zein-based colloidal particles-stabilized Pickering emulsions investigated by the in vitro digestion coupled with Caco-2 cell monolayer model.

Protein-based Pickering emulsions have received considerable attention as nutraceutical vehicles. However, the oral bioavailability of nutraceuticals encapsulated in Pickering emulsions was not well established. In this work, a simulated gastrointestinal tract/Caco-2 cell culture model was applied to investigate the oral bioavailability of quercetin encapsulated in zein-based Pickering emulsions with quercetin in zein particles as the control. Pickering emulsions with shell (ZCP-QE) and core quercetin (ZCPE-Q) were constructed, and quercetin bioaccessibility, cell uptake and secretion, and the overall bioavailability were evaluated and compared. The overall oral bioavailability of quercetin was increased from 2.71% (bulk oil) to 38.18% (ZCPs-Q) and 18.97% (ZCPE-Q), particularly reached 41.22% for ZCP-QE. This work took new insights into the contributions of bioaccessibility and absorption (cell uptake plus secretion) to the overall oral bioavailability of quercetin. A schematic representation is proposed to relate the types of colloidal nanostructures in the digesta to the uptake, cell absorption, and overall oral bioavailability of quercetin. This study provided an attractive basis for identifying effective strategies to improve the oral bioavailability of hydrophobic nutraceuticals.

Hofmeister Effect-Assistant Fabrication of All-Natural Protein-based Porous Materials Templated from Pickering Emulsions.

Porous materials derived from natural and biodegradable polymers have received growing interest. We demonstrate here an attractive method for the preparation of protein-based porous materials using emulsions stabilized by gliadin-chitosan hybrid particles (GCHPs) as the template, with the addition of gelatin and kosmotropic ions to improve the mechanical strength. The microstructure, mechanical properties, cytotoxicity, and fluid absorption behavior of porous materials were systematically investigated. This strategy facilitated the formation of porous materials with highly open and interconnected pore structure, which can be manipulated by altering the mass ratio of hexane or gelatin in the matrix. The Hofmeister effect resulted from kosmotropic ions greatly enhanced the Young's modulus and the compressive stress at 40% strain of porous materials from 0.56 to 6.84 MPa and 0.26 to 1.11 MPa, respectively. The developed all-natural porous materials were nontoxic to HaCaT cells; they also had excellent liquid (i.e., simulated body fluid and rabbit blood) absorption performance and advantages in resisting stress and maintaining geometry shape. The effects of different concentration amounts and type of salts in the Hofmeister series on the formation and performance of porous materials were also explored. Mechanical strength of porous materials was gradually enhanced when the (NH4)2SO4 concentration increased from 0 to 35 wt %, and the other four kosmotropic salts, including Na2S2O3, Na2CO3, NaH2PO4, and Na2SO4, also showed positive effects. This work opens a simple and feasible way to produce nontoxic and biodegradable porous materials with favorable mechanical strength and controllable pore structure. These materials have broad potential application in many fields involving biomedical and material science, such as cell culture, (bio)catalysis, and wound or bone defect healing.

Protein-Based Pickering High Internal Phase Emulsions as Nutraceutical Vehicles of and the Template for Advanced Materials: A Perspective Paper.

Pickering high internal phase emulsions (HIPEs) are normally highly concentrated emulsions stabilized by colloidal particles with a minimum internal phase volume fraction of 0.74. They have received considerable attention in many fields, including pharmaceuticals, tissue engineering, foods, and personal care products. The aim of this perspective is to update the current knowledge on the field of protein-based Pickering HIPEs, emphasizing those aspects that need to be explored and clarified. Research progress in constructing HIPEs by protein-type colloid particles and promising research trends in basic research and potential applications were highlighted. Promising studies in this field include (1) clarifying bioavailability and evolution of activity of active ingredients in Pickering HIPEs by oral administration, (2) constructing a Pickering interfacial catalysis platform using protein colloidal particles, and (3) expanding the emerging applications of Pickering HIPEs in fields, such as partially hydrogenated oil replacers, probiotic encapsulation, and the template for porous materials.

Lactobacillus reuteri improves gut barrier function and affects diurnal variation of the gut microbiota in mice fed a high-fat diet.

Lactobacillus reuteri FN041 is a secretory IgA-targeted Lactobacillus strain from human breast milk that has probiotic potential. The aim of this study was to test whether FN041 can alleviate dyslipidaemia and mucosal-barrier damage caused by a high-fat diet (HFD) and whether it can affect diurnal variation of the intestinal microbiota. C57BL/6 mice were fed either a normal chow diet or high-fat diet (HFD) for 7 weeks and were treated with either PBS as a control or L. reuteri FN041 for 4 weeks. Our results showed that FN041 treatment significantly attenuated HFD-induced weight gain (P < 0.01), accumulation of testicular fat, an increase in locomotor activity during the active phase (P < 0.01), triglyceridaemia, hypercholesterolaemia (P < 0.05), liver Fas overexpression, and Srebp1c mRNA expression inhibition. Moreover, FN041 treatment improved intestinal epithelial barrier function and induced a daily oscillation-dependent change in short-chain fatty acid production by the gut microbiota. A deeper understanding of the molecular pathways participating in intestinal barrier and microbiota modifications, and changes to lipid metabolism under the influence of FN041, will have important implications by potentially opening new horizons for the development of relevant foods to prevent metabolic disorders and unrelated intestinal diseases.

Fabrication and Characterization of Novel Water-Insoluble Protein Porous Materials Derived from Pickering High Internal-Phase Emulsions Stabilized by Gliadin-Chitosan-Complex Particles.

Pickering high internal-phase emulsions (HIPEs) and porous materials derived from the Pickering HIPEs have received increased attention in various research fields. Nevertheless, nondegradable inorganic and synthetic stabilizers present toxicity risks, thus greatly limiting their wider applications. In this work, we successfully developed nontoxic porous materials through the Pickering HIPE-templating process without chemical reactions. The obtained porous materials exhibited appreciable absorption capacity to corn oil and reached the state of saturated absorption within 3 min. The Pickering HIPE templates were stabilized by gliadin-chitosan complex particles (GCCPs), in which the volume fraction of the dispersed phase (90%) was the highest of all reported food-grade-particle-stabilized Pickering HIPEs so far, further contributing to the interconnected pore structure and high porosity (>90%) of porous materials. The interfacial particle barrier (Pickering mechanism) and three-dimensional network formed by the GCCPs in the continuous phase play crucial roles in stabilization of HIPEs with viscoelastic and self-supporting attributes and also facilitate the development of porous materials with designed pore structure. These materials, with favorable biocompatibility and biodegradability, possess excellent application prospects in foods, pharmaceuticals, materials, environmental applications, and so on.

Cellular Uptake and Intracellular Antioxidant Activity of Zein/Chitosan Nanoparticles Incorporated with Quercetin.

In this work, zein/chitosan nanoparticles (ZCPs-Q) were developed for encapsulating quercetin to overcome its lower water solubility and instability, and to concomitantly enhance its cellular uptake and intracellular antioxidant activity. This strategy enhanced quercetin solubility 753.6 and 9.95 times in water and PBS (7.4), respectively, and quercetin encapsulated in ZCPs remained stable after UV irradiation and heat treatment. ZCPs-Q could significantly attenuate AAPH induced erythrocyte hemolysis through the inhibition of ROS generation. It restored intracellular antioxidant enzyme (SOD and GSH-Px) activities to normal levels and inhibited intracellular malondialdehyde (MDA) formation. Simultaneously, ZCPs-Q showed a strong antioxidant activity in HepG2 cells with an EC50 value of 31.18 µg/mL, which was lower than free quercetin's 41.02 µg/mL. ZCPs enhanced the uptake efficiency of quercetin in Caco-2 cells, which contributed to the improvement of cellular antioxidant activities (CAA) evaluated with the CAA assay and AAPH-induced erythrocyte hemolysis assay. The designed route is particularly suitable for the encapsulation of water-insoluble nutraceuticals and for enhancing cell uptake and CAA.

Fabrication of Zein/Pectin Hybrid Particle-Stabilized Pickering High Internal Phase Emulsions with Robust and Ordered Interface Architecture.

Diets containing partially hydrogenated oils (PHOs) expose the human body to trans fatty acids, thus endangering cardiovascular health. Pickering high internal phase emulsions (HIPEs) is a promising alternative of PHOs. This work attempted to construct stable Pickering HIPEs by engineering interface architecture through manipulating the interfacial, self-assembly, and packing behavior of zein particles using the interaction between protein and pectin. Partially wettable zein/pectin hybrid particles (ZPHPs) with three-phase contact angles ranging from 84° to 87° were developed successfully. ZPHPs were irreversibly anchored at the oil-water interface, resulting in robust and ordered interfacial structure, evidenced by the combination of LB-SEM and CLSM. This situation helped to hold a percolating 3D oil droplet network, which facilitated the formation of Pickering HIPEs with viscoelasticity, excellent thixotropy (>91.0%), and storage stability. Curcumin in HIPEs was well protected from UV-induced degradation and endowed HIPEs with ideal oxidant stability. Fabricated Pickering HIPEs possess a charming application prospect in foods and the pharmaceutical industry.

Development of Pickering Emulsions Stabilized by Gliadin/Proanthocyanidins Hybrid Particles (GPHPs) and the Fate of Lipid Oxidation and Digestion.

This work attempted to engineer emulsions' interface using the special affinity between proline-rich gliadin and proanthocyanidins (PA), to develop surfactant-free antioxidant Pickering emulsions with digestive-resistant properties. This binding interaction between gliadin and PA benefited the interfacial adsorption of the particles to corn oil droplets. Pickering droplets as building units assembled into an interconnected three-dimensional network structure, giving the emulsions viscoelasticity and ultrastability. Oxidative markers in Pickering emulsions were periodically monitored under thermally accelerated storage. Lipid digestion and oxidation fates were characterized using in vitro gastrointestinal (GI) models. The interfacial membrane constructed by antioxidant particles served as a valid barrier against lipid oxidation and digestion, in a PA dose-dependent manner. Briefly, lipid oxidation under storage and simulated GI tract was retarded. Free fatty acid (FFA) fraction released decreased by 55% from 87.9% (bulk oil) to 39.5% (Pickering emulsion), implying engineering interfacial architecture potentially benefited to fight obesity. This study opens a facile strategy to tune lipid oxidation and digestion profiles through the cooperation of the Pickering principle and the interfacial delivery of antioxidants.

Development and characterization of novel antimicrobial bilayer films based on Polylactic acid (PLA)/Pickering emulsions.

Biodegradable food packaging is sustainable and has a great application prospect. PLA is a promising alternative for petroleum-derived polymers. However, PLA packaging suffers from poor barrier properties compared with petroleum-derived ones. To address this issue, we designed bilayer films based on PLA and Pickering emulsions. The formed bilayer films were compact and uniform and double layers were combined firmly. This strategy enhanced mechanical resistance, ductility and moisture barrier of Pickering emulsion films, and concomitantly enhanced the oxygen barrier for PLA films. Thymol loadings in Pickering emulsion layer endowed them with antimicrobial and antioxidant activity. The release profile of thymol was well fitted with Fick's second law. The antimicrobial activity of the films depended on film types, and Pickering emulsion layer presented larger inhibition zone than PLA layer, hinting that the films possessed directional releasing role. This study opens a promising route to fabricate bilayer architecture creating synergism of each layer.

Development of antioxidant Pickering high internal phase emulsions (HIPEs) stabilized by protein/polysaccharide hybrid particles as potential alternative for PHOs.

We report for the first time the usage of mono-dispersed gliadin/chitosan hybrid particles as a particulate emulsifier for Pickering high internal phase emulsions (HIPEs) development. The hybrid particles with partial wettability were fabricated at pH 5.0 using a facile anti-solvent route. Stable Pickering HIPEs with internal phases of up to 83% can be prepared with low particle concentrations (0.5-2%). The hybrid latexes were effectively adsorbed and anchored at the oil-water interface to exert steric hindrance against coalescence. Concomitantly, the compressed droplets in Pickering HIPEs to form a percolating 3D-network framework endowed the emulsions viscoelastic and self-standing features. The protective effect of Pickering HIPEs on curcumin was confirmed, and the content of primary oxidation products in HIPEs was slightly lower than that in bulk oil. This work opens an attractive strategy to convert liquid oils to viscoelastic soft solids without artificial trans fats, as a potential alternative for PHOs.

Hierarchical high internal phase emulsions and transparent oleogels stabilized by quillaja saponin-coated nanodroplets for color performance.

Herein, we report novel high internal phase emulsions and transparent oleogels that exhibit a hierarchical configuration by manipulating the spatial assembly of a natural small molecular-weight quillaja saponin for color performance. Quillaja saponin (QS) is a natural triterpenoid bidesmosidic from the soapbark tree (Quillaja saponaria Molina). Fairly monodispersed QS-coated nanodroplets (∼154 nm) were prepared using the ultrasonic emulsification strategy, and then used as block stabilizers for the fabrication of stable oil-in-water high internal phase emulsions (HIPEs, ϕ = 0.75). The resulting HIPEs can be easily converted into transparent oleogels with a very high oil loading (99.7%) through oven drying (70 °C). The jelly-like oleogels exhibit weak elastic, shear thinning behavior, good thixotropic recovery, and thermostabilization properties, which might be provided by the percolating 3D network of QS fibrils in the oil phase. We spatially tuned the color performance of the HIPEs and subsequent oleogels by locating the compositions of food colorants in different sections of their hierarchal architecture. The design and construction of hierarchical HIPEs and oleogels provide a promising new route for multitask functional delivery applications in various fields including food, cosmetics, and medical applications.

Tunable volatile release from organogel-emulsions based on the self-assembly of ß-sitosterol and γ-oryzanol.

A current challenge in the area of food emulsion is the design of microstructure that provides controlled release of volatile compounds during storage and consumption. Here, a new strategy addressed this problem at the fundamental level by describing the design of organogel-based emulsion from the self-assembly of ß-sitosterol and γ-oryzanol that are capable of tuning volatile release. The results showed that the release rate (v0), maximum headspace concentrations (Cmax) and partition coefficients (ka/e) above structured emulsions were significantly lower than unstructured emulsions and controlled release doing undergo tunable though the self-assembled interface and core fine microstructure from internal phase under dynamic and static condition. This result provides an understanding of how emulsions can behave as delivery system to better design novel food products with enhanced sensorial and nutritional attributes.

Phytosterol structured algae oil nanoemulsions and powders: improving antioxidant and flavor properties.

Algae oil, enriched with omega-3 long-chain polyunsaturated fatty acids (ω-3 LC-PUFA), is known for its health benefits. However, protection against lipid oxidation as well as masking of unpleasant fishy malodors in algae oil enriched foods is a big challenge to achieve. In this study, we firstly achieved a one-pot ultrasound emulsification strategy (alternative heating-homogenization) to prepare phytosterol structured thermosensitive algae oil-in-water nanoemulsion stabilized by quillaja saponin. After spray drying, the resulting algae oil powders from the structured nanoemulsion templates exhibit an excellent reconstructed behavior, even after 30 d of storage. Furthermore, an enhanced oxidative stability was obtained by reducing both the primary and secondary oxidation products through formulation with ß-sitosterol and γ-oryzanol, which are natural antioxidants. Following the results of headspace volatiles using dynamic headspace-gas chromatography-mass spectrometry (DHS-GC-MS), it was clear that the structured algae oil-loaded nanoemulsion and powder had lower levels of fishy off-flavour (e.g., (Z)-heptenal, decanal, ethanone, and hexadecenoic acid), whereas the control emulsion and oil powder without structure performed worse. This study demonstrated that the structure from phytosterols is an effective strategy to minimize the fishy off-flavour and maximize oxidative stability of both algae oil nanoemulsions and spray-dried powders, and opens up the possibility of formulation design in polyunsaturated oil encapsulates as novel delivery systems to apply in functional foods and beverages.

Fabrication and characterization of Pickering emulsions and oil gels stabilized by highly charged zein/chitosan complex particles (ZCCPs).

Herein, we reported a facile method to fabricate ultra-stable, surfactant- and antimicrobial-free Pickering emulsions by designing and modulating emulsions' interfaces via zein/chitosan colloid particles (ZCCPs). Highly charged ZCCPs with neutral wettability were produced by a facile anti-solvent procedure. The ZCCPs were shown to be effective Pickering emulsifiers because the emulsions formed were highly resistant to coalescence over a 9-month storage period. The ZCCPs were adsorbed irreversibly at the interface during emulsification, forming a hybrid network framework in which zein particles were embedded within the chitosan network, yielding ultra-stable food-grade zein/chitosan colloid particles stabilized Pickering emulsions (ZCCPEs). Moreover, stable surfactant-free oil gels were obtained by a one-step freeze-drying process of the precursor ZCCPEs. This distinctive interfacial architecture accounted for the favourable physical performance, and potentially oxidative and microbial stability of the emulsions and/or oil gels. This work opens up a promising route via a food-grade Pickering emulsion-template approach to transform liquid oil into solid-like fats with zero trans-fat formation.

The influence of heat treatment on acid-tolerant emulsions prepared from acid soluble soy protein and soy soluble polysaccharide complexes.

This research presents a green procedure to prepare oil in water (O/W) emulsion from acid soluble soy protein (ASSP) and soy soluble polysaccharide (SSPS), a long-term stable nanoscale system for delivering the lipophilic components. The emulsion technique involved the preparation complexion using ASSP and SSPS by electrostatic and hydrophobic interactions as well as high pressure homogenization. The average diameter of the droplet of emulsions (fresh and heated) is 263±2nm. Such emulsions resulted in heating stable dispersions containing corn oil at the concentration of 20.0%, even at the pH around the isoelectric points of ASSP. After 90days storage at 4°C, the mean diameter of emulsions after heating at 80°C for 60min is 314±1nm compared with 341±3nm of emulsions unheated. The heat-stability of dispersions were affected by emulsion conditions, so the present research demonstrates the emulsion stability against heat treatment, ionic strength and pH change.

Pickering Emulsion Gels Prepared by Hydrogen-Bonded Zein/Tannic Acid Complex Colloidal Particles.

Food-grade colloidal particles and complexes, which are formed via modulation of the noncovalent interactions between macromolecules and natural small molecules, can be developed as novel functional ingredients in a safe and sustainable way. For this study was prepared a novel zein/tannic acid (TA) complex colloidal particle (ZTP) based on the hydrogen-bonding interaction between zein and TA in aqueous ethanol solution by using a simple antisolvent approach. Pickering emulsion gels with high oil volume fraction (φ(oil) > 50%) were successfully fabricated via one-step homogenization. Circular dichroism (CD) and small-angle X-ray scattering (SAXS) measurements, which were used to characterize the structure of zein/TA complexes in ethanol solution, clearly showed that TA binding generated a conformational change of zein without altering their supramolecular structure at pH 5.0 and intermediate TA concentrations. Consequently, the resultant ZTP had tuned near neutral wettability (θ(ow) ∼ 86°) and enhanced interfacial reactivity, but without significantly decreased surface charge. These allowed the ZTP to stabilize the oil droplets and further triggered cross-linking to form a continuous network among and around the oil droplets and protein particles, leading to the formation of stable Pickering emulsion gels. Layer-by-layer (LbL) interfacial architecture on the oil-water surface of the droplets was observed, which implied a possibility to fabricate hierarchical interface microstructure via modulation of the noncovalent interaction between hydrophobic protein and natural polyphenol.

Fabrication and Characterization of Stable Soy ß-Conglycinin-Dextran Core-Shell Nanogels Prepared via a Self-Assembly Approach at the Isoelectric Point.

The preparation of soy ß-conglycinin-dextran nanogels (∼90 nm) went through two stages, which are safe, facile, and green. First, amphiphilic graft copolymers were formed by dextran covalently attaching to ß-conglycinin via Maillard dry-heating reaction. Second, the synthesized conjugates were heated above the denaturation temperature at the isoelectric point (pH4.8) so as to assemble nanogels. The effects of pH, concentration, heating temperature, and time on the fabrication of nanogels were examined. The morphology study displayed that the nanogels exhibited spherical shape with core-shell structures, which was reconfirmed by zeta-potential investigation. Both circular dichroism spectra and surface hydrophobicity analyses indicated that the conformations of ß-conglycinin in the core of nanogels were changed, and the latter experiment further revealed that the hydrophobic groups of ß-conglycinin were exposed to the surface of protein. The nanogels were stable against various conditions and might be useful to deliver hydrophobic bioactive compounds.

Effect of Monascus aged vinegar on isoflavone conversion in soy germ by soaking treatment.

Soy germ rich in isoflavones has attracted much attention for health-promoting characteristics. An effective approach via Monascus aged vinegar soaking was adopted to enhance the aglycone amount. The profiles and interconversion of soy germ isoflavones via Monascus aged vinegar soaking were investigated, and the distribution in vinegars were also explored. The aglycones were dramatically increased by 40.76 times. Concomitantly, ß-glycosides and malonylglycosides were significantly decreased. The proportion of aglycones presented a sharp increase with the endogenous ß-glucosidase activity at the initial 4h incubation. There appeared to be correlations between ß-glucosidase activity and the hydrolysis of conjugated isoflavones. The results demonstrated that the reactions of decarboxylation, de-esterification and de-glycosylation were involved in the Monascus aged vinegar soaking, supporting synergistic effects of enzymolysis by endogenous ß-glucosidase from soy germ and acid hydrolysis of vinegars. Soaking by vinegar is a promising pathway for preparing aglycone-rich soy germ.