Microgel Particles Research Articles

Effect of oil phases on the stability of myofibrillar protein microgel particles stabilized Pickering emulsions: The leading role of viscosity

The Pickering emulsion may be restricted in the foods owing to the unreasonable use of oils. Herein, the effect of different oil phases on the stability of myofibrillar protein microgel particles stabilized Pickering emulsions was investigated. Results showed sunflower oil Pickering emulsions with high stability have the smallest droplet size (−26.17 μm). While peanut oil Pickering emulsions have the largest droplet size (−77.00 μm) and poor emulsion stability. The fatty acid analysis showed sunflower oil had low content of saturated (15.68 %) and super-long-chain (0) fatty acids, while peanut oil had high content of saturated (23.67 %) and super-long-chain (9.02 %) fatty acids, leading to a difference in viscosity. Low viscosity was more conducive to dispersing oil droplets and inhibiting the floating and gathering of droplets, thus enhancing the emulsion stability. Therefore, the oil with low content of super-long-chain and saturated fatty acids could be suitable for preparing MMP Pickering emulsions.

Study on oil body emulsion gels stabilized by composited polysaccharides through microgel particles compaction and natural gelation

Oil bodies (OBs), oil storage organelles of oilseeds, are natural, green, and sustainable products that have received much attention in recent years. Different ratios (4:0, 3:1, 2:2, 1:3, 0:4, w/w) of gelatinous polysaccharide κ-carrageenan (κ-Car) mixed with non-gelatinous polysaccharide xanthan (Xan) were used to stabilize OB emulsion gels by microgel particles (MPs) compaction or natural gelation with a total polysaccharide concentration of 0.5 wt%, respectively. Effects of two different treatments of polysaccharides on OB emulsion gels were compared by Fourier transform infrared spectroscopy (FTIR), rheology, and varied microscopy techniques, respectively. For natural gelation, the texture of OB emulsion gels was too rough to be employed in the food system. After compounding κ-Car with Xan, κ-Car and Xan were cross-linked to form a tighter network structure which improved the stability of OB emulsion gels by restricting the movement of OBs and water. Besides, the texture of OB emulsion gels became homogeneous. In addition, MPs compacted closely as micro-units to form a different type of network could benefit to homogeneous texture. The surface area of gels was expanded after microgel treatment, and the hydrogen bond strength enhanced. Unfortunately, the water seepage was more severe after microgel treatment. However, with the increase of Xan proportion before microgel treatment, the instability of OB emulsion gels stabilized by MPs could be improved significantly. This study allowed us to gain a better understanding of tailoring the texture of OB emulsion gels and broadening the application of OBs to low-fat food systems. • The stability of oil body emulsion gels can be advanced by mixing polysaccharides. • Microgel particles facilitated uniform texture of oil body emulsion gels. • Dense network structure was beneficial to the stability of oil body emulsion gels.

Autonomic self-regulating systems based on polyelectrolyte microcapsules and microgel particles

Biological systems possess unique non-equilibrium functions, maintaining tight manipulation of their surroundings through inter-communication of multiple components and self-regulatory capability organized over different length scales. However, most artificial materials are incapable of communicating and self-regulating behavior due to their limited number of component and direct responsive modes. Herein, a new integrated self-regulation system is developed utilizing stimuli-responsive polyelectrolyte capsules as building blocks. The combination of stimuli-responsive capsules and enzyme immobilized microgels is designed to mimic life systems and its programmable interactive communications and self-regulation behavior is demonstrated through communication-feedback mechanism. Polyelectrolyte capsules can sense changes of their surrounding, then start the internal communication by releasing energy-rich cargo mimicking the behavior of the cells. The microgel particles subsequently complete closed-loop communication through providing negative feedback on capsules by enzymatic reaction and actuating pH-regulation of the whole system. Different communication modes and pH-regulation behaviors could be achieved by adjusting spatial and kinetic conditions. Proposed intelligent system is highly customizable due to the wide selection of encapsulated cargos, stimuli-responsive blocks and reaction networks, and would have broad influences in areas ranging from medical implants that assist in stabilizing body functions to microreactor system that regulate catalytic reactions.

Transport of ionic species affected by interactions with a pH-sensitive monolayer of microgel particles attached to electrode surface

In this work, we present the use of pH-sensitive microgel based on acrylic acid crosslinked with N,N′-bis(acryloyl)cystamine in the modification of Au electrode surface through the chemisorption process. The strong interactions between the crosslinker disulfide bridges and the gold surface were employed. The shape and morphology of the microgel particles were determined using scanning electron microscopy (SEM). The gel sensitivity to pH was examined using the dynamic light scattering technique (DLS). The impact of pH on electrode processes at the modified Au surface was studied using cyclic voltammetry (CV). It was found that at appropriate pH the microgel particles formed a loose monolayer on the electrode surface, which, in the swollen state, was able to block the transport of negatively charged redox probe to the electrode surface. On the other hand, when the microgels were in the shrunken state, the electrode surface was partially uncovered, and that allowed the redox probe to reach the electrode surface. The anchoring process of the microgels on the Au electrode surface was monitored with a quartz crystal microbalance with dissipation technique (QCM-D). The electrochemical properties of the modified with the pH-sensitive microgel layer electrodes were examined in the presence of either positively or negatively charged redox probes using CV and electrochemical impedance spectroscopy (EIS). It turned out that the electrochemical signals were strongly affected by both: degree of swelling of the microgel and protonation of the carboxylic groups of acrylic acid in the polymer network. The switching of electrode behavior was fully reversible and relatively fast.

A Facile yet Versatile Strategy to Construct Liquid Hybrid Energy-Saving Windows for Strong Solar Modulation.

Smart windows with light management and indoor solar heating modulation capacities are of paramount importance for building energy conservation. Thermochromic poly(N-isopropylacrylamide) (PNIPAm) hydrogel smart windows exhibit advantages of the relatively suitable transition temperature of 32 °C, high cost-effective and automatic passive sunlight regulation, but sustain slow response rate and unsatisfactory solar modulation efficiency. Herein, a strategy of one-step copolymerization of NIPAm and different olefine acids (OA) using reverse atom transfer radical polymerization method is developed to fabricate various chain/microparticle hybrids (CMH) for liquid energy-saving windows. Synergetic mechanisms of thermal-induced dissolution and aggregation of linear polymer chains integrated with water capture and release of microgel particles contribute to tunable light-scattering behaviors and adaptive solar modulation. Without any post-treatment, the as-prepared poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAm-co-AA))-based CMH suspension is injected into sandwich glass to construct energy-saving windows, which exhibits appreciated near-room-temperature transition (26.7 °C), rapid response (5 s), extraordinary luminous transmittance (91.5%), and solar modulation efficiency (85.8%), resulting in a substantial decline of indoor temperature of 24.5 °C in simulation experiment. Combining the versatile strategy with flexible adjustment on transition temperature, multifarious P(NIPAm-co-OA)-based CMH windows with eminent light management capacity are obtained. This work will powerfully promote the development and renovation of energy-efficient windows.

Polymerized stimuli-responsive microgels for the removal of organic dye from water

Polymerized hydrogel materials (PGM) containing uniform-sized stimuli-responsive microgel particles could be promising alternatives for solution-based microgels to remove organic dyes from water. In the current work, PGM is prepared using Poly(N-isopropylacrylamide-co-acrylic acid) based anionic microgels and their ability for uptake and release studies with an oppositely charged dye, methylene blue (MB) is carried out using UV–vis spectroscopy. The mechanism of dye adsorption is understood at a single particle level using light scattering, and zeta potential and the contributions from different molecular interactions among dye molecules and constituting entities of microgels are obtained from molecular docking studies. The maximum dye uptake by PGM is around 80 % in the swollen state (at pH 7 and 20 °C). In contrast, the dye release studies in the deswollen state (at pH 3 and 50 °C) show a decrease in the release efficiency from 87 % to 63 % of the total dye adsorbed in 4-repeated cycles. The adsorption isotherm follows a sigmoidal (S) model that has been majorly used in different multi-layer adsorption systems. Extensive dynamic and static light scattering studies demonstrate a deswelling of hydrodynamic radius and core–shell radius of microgels at low temperatures (20 °C) induced by dye adsorption. At higher temperatures, the dye-adsorbed microgels have a higher hydrodynamic radius than the pure microgels due to the remaining dye molecules within the microgel that do not release even in the deswollen state. Molecular docking studies show that electrostatic interaction dominates between COO– and MB and van der Waals/hydrophobic dominates for MB-NIPAM and MB-COOH docking complex respectively. Our work covering adsorption/desorption properties of the material to the single-particle level can provide a better understanding in formulating reusable smart materials for the remediation of different water pollutants.

Antibody-functionalized, stimuli responsive microgel gold-hybrid colloids: synthesis, characterizations and their use in pathogen detection

Antibody-functionalized hybrid microgels serve as an innovative approach for various translational applications particularly for detection of pathogens. We have synthesized Poly (N-isoproplyacrylamide)-co-poly(acrylic acid) (PNIPAm-PAA) based microgels encapsulated with gold nanoparticles followed by loading on antibodies specific to diarrheal pathogen, Salmonella typhimurium using the established streptavidin-biotin chemistry. Antibody-loaded hybrid microgel particles are further characterized with respect to their loading efficiencies using UV-Vis spectrometry and pH/temperature-dependent swelling using dynamic light scattering. Our results showed that streptavidin-coated hybrid gold nanoparticles bind to biotinylated antibodies with high affinity. From UV-Vis spectroscopy, it was observed that antibody-conjugated PNIPAM-AuNS showed two peaks; one at a wavelength of 540 nm due to gold nanoparticles and another at a wavelength of 280 nm due to antibodies. The effect of temperature on the hydrodynamic radius (Rh) of PNIPAM microgel particles, PNIPAM-AuNS, streptavidin-coated PNIPAM-AuNS and biotinylated antibodies conjugated with PNIPAM-AuNS was determined by dynamic light scattering which was further confirmed from the temperature dependant swelling of these biotinylated antibodies loaded onto hybrid microgels which exhibit less thermoresponsivity than the control hybrid microgels. Our results establish stimuli-responsive polymer hybrids as important new hybrid biomaterials for the detection of Salmonella typhimurium.

Myofibrillar protein microgels stabilized high internal phase Pickering emulsions with heat-promoted stability

This study developed the myofibrillar protein microgel particles (MMP) stabilized high internal phase Pickering emulsions (HIPPEs) with heat-promoted stability. The effect of heat treatment intensity and the heat-promoted stabilization mechanism were investigated by analyzing the microstructure, rheology and interface properties of MMP stabilized HIPPEs. The storage modulus of emulsions displayed an increased trend during the heating up and then cooling down processes. The droplet size of HIPPEs gradually increased with increasing heat treatment intensity (60-121 °C for 5 or 30 min) and still remained stable after heat treatment above 100 °C for 30 min. The heat treatment resulted in the enhancement of the freeze-thaw and centrifugal stability of HIPPEs, implying a dominant contribution to the improvement of emulsion stability. The heat treatment promoted the hydrophobic interactions between MMP at the interface and the gradual formation of interface network structure. Then, it was also observed that a gradual increase in the interfacial expansion modulus (4.6–8.1 mN/m) and the formation of a high strength elastic film. This work provides a facile strategy to improve the stability of protein microgel stabilized HIPPEs, which is beneficial to the development of thermal processing emulsion-based foods.

Controlling Kinetic Pathways in Demixing Microgel-Micelle Mixtures.

We investigate the temperature-dependent phase behavior of mixtures of poly(N-isopropylacrylamide) (pNIPAM) microgel colloids and a triblock copolymer (PEO-PPO-PEO) surfactant. Usually, gelation in these systems results from an increase in temperature. Here we investigate the role of the heating rate, and surprisingly, we find that this causes the mechanism of aggregation to change from one which is driven by depletion of the microgels by the micelles at low temperatures to the association of the two species at high temperatures. We thus reveal two competing mechanisms for attractions between the microgel particles which can be controlled by changing the heating rate. We use this heating-rate-dependent response of the system to access multiple structures for the same system composition. Samples were found to demix into phases rich and poor in microgel particles at temperatures below 33 °C, under conditions where the microgels particles are partially swollen. Under rapid heating full demixing is bypassed, and gel networks are formed instead. The temperature history of the sample, therefore, allows for kinetic selection between different final structures, which may be metastable.

Electron Conductive and Transparent Hydrogels for Recording Brain Neural Signals and Neuromodulation.

Recording brain neural signals and optogenetic neuromodulations openfrontiers in decoding brain neural information and neurodegenerative disease therapeutics. Conventional implantable probes suffer from modulus mismatch with biological tissues and an irreconcilable tradeoff between transparency and electron conductivity. Herein, a strategy is proposed to address these tradeoffs, which generates conductive and transparent hydrogels with polypyrrole-decorated microgels as cross-linkers. The optical transparency of the electrodes can be attributed to the special structures that allow light waves to bypass the microgel particles and minimize their interaction. Demonstrated by probing the hippocampus of rat brains, the biomimetic electrode shows a prolonged capacity for simultaneous optogenetic neuromodulation and recording of brain neural signals. More importantly, an intriguing brain-machine interaction is realized, which involves signal input to the brain, brain neural signal generation, and controlling limb behaviors. This breakthrough work represents a significant scientific advancement toward decoding brain neural information and developing neurodegenerative disease therapies.

Micron sized anionic poly (methacrylic acid) microgel particles for the adsorptive elimination of cationic water pollutants

Abstract In this article, we reported the micron sized particles of poly (methacrylic acid) (p [MAA]) microgel and explored their applications as anionic adsorbents. The micron sized particles of poly (methacrylic acid) microgel were prepared by a simple inverse suspension polymerization method. The adsorptive elimination of adsorbates of cationic nature including malachite green (MG) and methylene blue (MB) from the aqueous medium was studied systematically. The adsorption tests were carried out using various initial concentrations of dyes and with different amounts of adsorbents. The adsorption equilibrium was established in 60 min. The adsorption capacity of the p (MAA) microgel was found as high as 351 mg/g for MG and 65 mg/g for MB. The maximum removal percentage for MG and MB was recorded as 88 and 68%, respectively. The adsorption data was computed with adsorption isotherm models including Langmuir, Freundlich, and Temkin. The Langmuir model was observed to be more applicable for the adsorption of MG while the adsorption of MB was best matched with Temkin model. The adsorption data was also treated with pseudo first order and pseudo second order kinetic models along with intraparticle diffusion and Elovich models. The pseudo second order kinetic model was most suitable with adsorption of both the MG and MB.

Tribology and rheology of water-in-water emulsions stabilized by whey protein microgels

This study aimed to investigate the microstructural, tribological and rheological properties of water-in-water (W/W) emulsion droplets with or without stabilization by proteinaceous microgel particles. The W/W emulsions were prepared from mixtures of gelatinized corn starch (GS) and κ -carrageenan ( κ C) in the two-phase regime and when particle-stabilized whey protein microgel particles (WPM) were used. The W/W emulsions were shear thinning liquids. The viscosity values of the emulsions were higher than the corresponding weight average values, calculated on individual samples irrespective of shear rates. Tribological results revealed that the frictional properties of W/W emulsions formed from 1.0 wt% GS + 0.1 w% κ C were dominated by the κ C properties alone in the mixed and hydrodynamic regimes, even though the starch played an essential role in decreasing friction coefficient ( μ ) in the boundary regime. Unlike the corresponding solutions of GS and κ C, W/W emulsions containing higher concentrations of the biopolymers (3.0 wt% starch + 0.3 wt% κ C) decreased μ in the mixed and boundary regimes, probably due to water droplets becoming entrained and forming a hydration film in the contact region. In the case of W/W emulsions containing WPM, confocal and cryo-scanning electron microscopy confirmed the presence of WPM at the interface and hence a Pickering-like stabilization. The WPM-stabilized W/W emulsions showed higher apparent viscosity (than those without WPM) and lower μ in the boundary and mixed regimes. Stabilization of W/W emulsions via microgel particles therefore seems to be a useful tool to improve the lubrication performance of such systems. • Water-in-water (W/W) emulsion was designed using starch (GS) and κ -carrageenan ( κ C). • Whey protein microgel (WPM) was used to stabilize W/W emulsion droplets. • WPM at the W–W interface was observed using microscopy across length scales. • The viscosity of W/W droplets was enhanced in presence of WPM. • WPM improved lubricity of W/W droplets in the boundary and mixed regimes.

Strain stiffening elastomers with swelling inclusions.

Inhomogeneously swollen elastomers are an emergent class of materials, comprising elastic matrices with inclusion phases in the form of microgel particles or osmolytes. Inclusion phases can undergo osmotically driven swelling and deswelling over orders of magnitude. In the swollen state, the inclusions typically have negligible Young's modulus, and the matrix is strongly deformed. In that regime, the effective mechanical properties of the composite are governed by the matrix. Laying the groundwork for a generic analysis of inhomogeneously swollen elastomers, we develop a model based on incremental mean-field homogenization of a hyperelastic matrix. The framework allows for the computation of the macroscopic effective stiffness for arbitrary hyperelastic matrix materials. For an in-depth quantification of the local effective stiffness, we extend the concept of elastic stiffness maps to incompressible materials. For strain-stiffening materials, stiffness maps in the swollen state highlight pronounced radial stiffening with a non-monotonic change in stiffness in the hoop direction. Stiffening characteristics are sensitive to the form of constitutive models, which may be exploited in the design of hydrated actuators, soft composites and metamaterials. For validation, we apply this framework to a Yeoh material, and compare to recently published data. Model predictions agree well with experimental data on elastomers with highly swollen embedded microgel particles. We identify three distinct regimes related to an increasing degree of particle swelling: first, an initial decrease in composite stiffness is attributed to particle softening upon liquid intake. Second, dilute particle swelling leads to matrix stiffening dominating over particle softening, resulting in an increase in composite stiffness. Third, for swelling degrees beyond the dilute limit, particle interactions dominate further matrix stiffening.

50/50 oil/water emulsion stabilized by pea protein isolate microgel particles/xanthan gum complexes and co-emulsifiers

Properties of 50/50 oil/water emulsion stabilized by pea protein isolate microgel particles (PPIMP)/xanthan gum (XG) and co-emulsifiers were evaluated. Three surfactants with different charging characteristics (lauric arginate, LAE, cationic surfactant; diacetyl tartaric acid esters of mono- and diglycerides, DATEM, nonionic surfactant; sodium stearyl lactate, SSL, anionic surfactant) were selected to co-stable emulsion systems with PPIMP/XG, respectively. The emulsions stabilized by PPIMP/XG with LAE reached the minimal droplet size (21.5 μm). The increased addition of either DATEM or SSL decrease the droplet size of emulsion (except for the 0.8 wt% SSL). The emulsions showed lower apparent viscosity at higher DATEM concentration, whereas the vice-versa was observed in the prepared emulsions with SSL. Surfactants with different charge properties can affect the antioxidant properties of the emulsions. All the emulsions containing LAE, DATEM, or SSL can inhibit oxidation by adjusting the concentration, which could be confirmed in a study on the retention of resveratrol. This study provides a deeper insight into the emulsions co-stabilized by different emulsifiers and can be applied in edible O/W emulsions in the food industry like egg-free mayonnaise. • Pea protein microgels and xanthan gum can obtain stable 50 wt% O/W emulsion. • 0.02 wt% lauric arginate in emulsion reduced droplet size and increased viscosity. • Non-ionic surfactant fell emulsion's viscosity and G′, anionic one did opposite. • The existence of surfactants could enhance the oxidation stability of emulsions.

Measuring dn/dc for Polysaccharide Microgels of Varying Crosslinking Density

Static light scattering (SLS) is a powerful, noninvasive experimental method that yields the molecular weight (average molecular weight, Mw), the size (radius of gyration, Rg), and the interactions between the scatters (the second virial coefficient, A2). However, proper SLS measurements require determination of the specific refractive index increment (dn/dc) for the samples studied. While tables of dn/dc values are available for various substances, they are not generally available for microgel particles, which in our case are crosslinked chains of an amphiphilic polymer. This paper is focused on measuring dn/dc for microgel samples of varying crosslinking concentrations. Microgel dn/dc values were found to be different from the value of the parent polymer given in literature and found to have a temperature dependence as well as a crosslinker concentration dependence at higher crosslinker concentrations. Using the measured values of microgel dn/dc instead of tabulated parent polymer values on estimates of microgel Mw, Rg, and A2 highlights the importance of direct dn/dc measurements for samples studied by SLS.

Transient co-assemblies of micron-scale colloids regulated by ATP-fueled reaction networks.

Self-assembly of colloidal particles offers an attractive bottom-up approach to functional materials. Current design strategies for colloidal assemblies are mostly based on thermodynamically controlled principles and lack autonomous behavior. The next advance in the properties of colloidal assemblies will come from coupling these structures to out-of-equilibrium chemical reaction networks furnishing them with autonomous and dynamic behavior. This, however, constitutes a major challenge of carefully modulating the interparticle potentials on a temporal circuit program and avoiding kinetic trapping and irreversible aggregation. Herein, we report the coupling of a fuel-driven DNA-based enzymatic reaction network (ERN) to micron-sized colloidal particles to achieve their transient co-assembly. The ERN operating on the molecular level transiently releases an Output strand which links two DNA functionalized microgel particles together into co-assemblies with a programmable assembly lifetime. The system generates minimal waste and recovers all components of the ERN after the consumption of the ATP fuel. The system can be reactivated by addition of new fuel as shown for up to three cycles. The design can be applied to organize other building blocks into hierarchical structures and materials with advanced biomimetic properties.

Polyphenol-Enriched Protein Oleogels as Potential Delivery Systems of Omega-3 Fatty Acids.

Omega-3 polyunsaturated fatty acids (n-3 FAs) are essential nutrients and are considered effective in improving human health. Recent studies highlight the importance of the combination of n-3 FAs and polyphenols for limiting the oxidation of n-3 FAs and exhibiting synergistic beneficial effects. Herein, we developed a novel formulation technology to prepare oleogels that could be used for the codelivery of n-3 FAs and polyphenols with high loading efficacy and oxidative stability. These oleogels are made from algal oil with polyphenol-enriched whey protein microgel (WPM) particles as gelling agents via simple and scalable ball milling technology. The oxidative status, fatty acid composition, and volatiles of protein oleogels during accelerated storage were systematically assessed by stoichiometry and gas chromatography-mass spectrometry. These results showed that protein oleogels could overcome several challenges associated with the formulation of n-3 oils, including long-term oxidative stability and improved sensory and textural properties. The protein oleogel system could provide an excellent convenience for formulating multiple nutrients and nutraceuticals with integrating health effects, which are expected to be used in the care of highly vulnerable populations, including children, the elderly, and patients.

Multicompartment polymeric colloids from functional precursor Microgel: Synthesis in continuous process

Raspberry-like poly(oligoethylene methacrylate-b-N-vinylcaprolactam)/polystyrene (POEGMA-b-PVCL/PS) patchy particles (PPs) and complex colloidal particle clusters (CCPCs) were fabricated in two-, and one-step (cascade) flow process. Surfactant-free, photo-initiated reversible addition-fragmentation transfer (RAFT) precipitation polymerization (Photo-RPP) was used to develop internally cross-linked POEGMA-b-PVCL microgels with narrow size distribution. Resulting microgel particles were then used to stabilize styrene seed droplets in water, producing raspberry-like PPs. In the cascade process, different hydrophobicity between microgel and PS induced the self-assembly of the first formed raspberry particles that then polymerized continuously in a Pickering emulsion to form the CCPCs. The internal structure as well as the surface morphology of PPs and CCPCs were studied as a function of polymerization conditions such as flow rate/retention time (Rt), temperature and the amount of used cross-linker. By performing Photo-RPP in tubular flow reactor we were able to gained advantages over heat dissipation and homogeneous light distribution in relation to thermally-, and photo-initiated bulk polymerizations. Tubular reactor also enabled detailed studies over morphological evolution of formed particles as a function of flow rate/Rt.

Structure maintainability of safflomin/betanin incorporated gelatin-chitooligosaccharide complexes based high internal phase emulsions and its combinational 3D printing

Safflomin A and betanin are incorporated into gelatin-chitooligosaccharide based complexes for stabilizing functional internal phase emulsions (HIPEs), which hold promise in 3D printing. Intermolecular interactions and good compatibility among gelatin, chitooligosaccharide and proper-content bioactive materials promoted the thermal stability (increased from 310.82 to 316.32 °C, or from 284.97 to 311.70 °C), dispersion stability (high UV absorbance) and microgel particles (around 358.67 or 408.30 nm) of complexes. The complexes illustrated great oil-water interfacial adsorption behaviors (kdiff = 0.29 mN m−1 s−0.5, π1600 = 21.71 mN/m) and dilatational viscoelasticity for interfacial membrane, implying high elasticity and interface stability. The strong droplet membrane and the compact gel network resulted in HIPEs to possess certain chemical stability (low color fading, e. g., under pH = 4), high centrifugation stability, shaking stability and freeze-thaw stability with low-diameter droplets. In addition to the excellent shear-thinning property (n1 < 1), HIPEs containing safflomin A or betanin had the systems with high degree of structuring (high η0 1.02 × 106 mPa s and 1.12 × 106 mPa s, respectively), excellent structure reversibility (high thixotropic index 7.62 and recovery index 71.76%; thixotropic index 6.87 and recovery index 77.29%, respectively), outstanding thixotropic performance (high thixotropic area 1872.01 Pa/s and 975.61 Pa/s, respectively), favorable self-supporting ability (recovery rates 92.01% and 94.61%, respectively), and high mechanical strength (yield stresses 21.32 Pa and 17.8 Pa after storage of 9 months), indicating the satisfactory structure maintainability. The screw-3D printing of HIPEs displayed high shape retention with low shape deviation (<5% for safflomin A- and betanin-based HIPEs), and certified the excellent printability. This study provides information for fabricating bioactive materials-HIPEs with desired structure, and manifests the potential of HIPEs in manufacturing functional, innovative food with high quality.

Enhanced Bioavailability and Pharmacokinetics of a Natural Self-Emulsifying Reversible Hybrid-Hydrogel System of Quercetin: A Randomized Double-Blinded Comparative Crossover Study.

Despite the vast array of health beneficial pharmacological effects, the bioavailability of the dietary flavonoid quercetin was found to be poor due to insolubility, incompatibility, and rapid biotransformation. Herein, we investigated the solubility, morphology, particle size, stability, in vitro release, and human pharmacokinetics of a hybrid-hydrogel formulation of quercetin (FQ-35) using fenugreek galactomannans as the hydrogel scaffold. Physicochemical characterization revealed that the crystalline quercetin was well encapsulated in the hydrogel matrix to form translucent microgel particles of FQ-35 with enhanced solubility (96-fold). The mean particle size was found to be 183.6 ± 42.7 nm with a zeta potential of 35.1 ± 3.8 mV. Pharmacokinetic investigation on healthy volunteers (N = 16) employing tandem mass spectrometric (ultra-performance liquid chromatography-electrospray tandem mass spectrometry) measurements of the concentration of free (unconjugated) and conjugated quercetin metabolites revealed an 18.6-fold improvement in free (unconjugated) quercetin bioavailability and 62-fold improvement in total quercetin (sum of free and conjugated) bioavailability, compared to the unformulated quercetin extracted from Sophora japonica. In summary, the natural self-emulsifying reversible hybrid-hydrogel delivery system was found to offer significant solubility, stability, and bioavailability of quercetin upon single-dose oral administration.