Effect of sodium starch octenyl succinate-based Pickering emulsion on the physicochemical properties of hairtail myofibrillar protein gel subjected to multiple freeze-thaw cycles

A Pickering emulsion based on sodium starch octenyl succinate(SSOS)was prepared and its effects on the physicochemical properties of hairtail myofibrillar protein gels(MPGs)subjected to multiple freeze-thaw(F-T)cycles were investigated.The whiteness,water-holding capacity,storage modulus(G')and texture properties of the MPGs were significantly improved by adding 1%-2%Pickering emulsion(P<0.05).Meanwhile,Raman spectral analysis demonstrated that Pickering emulsion promoted the transformation of secondary structure,enhanced hydrogen bonds and hydrophobic interactions,and promoted the transition of disulfide bond conformation from g-g-g to g-g-t and t-g-t.At an emulsion concentration of 2%,theα-helix content decreased by 10.37%,while theβ-sheet content increased by 7.94%,compared to the control.After F-T cycles,the structure of the MPGs was destroyed,with an increase in hardness and a decrease in whiteness and water-holding capacity,however,the quality degradation of MPGs was reduced with 1%-2%Pickering emulsion.These findings demonstrated that SSOS-Pickering emulsions,as potential fat substitutes,can enhance the gel properties and the F-T stability of MPGs.

Pickering emulsion transport in skeletal muscle tissue:A dissipative particle dynamics simulation approach

Lymph node targeting is a commonly used strategy for particulate vaccines,particularly for Pickering emulsions.However,extensive research on the internal delivery mechanisms of these emulsions,especially the complex intercellular interactions of deformable Pickering emulsions,has been surprisingly sparse.This gap in knowledge holds significant potential for enhancing vaccine efficacy.This study aims to address this by summarizing the process of lymph-node-targeting transport and introducing a dissipative particle dynamics simulation method to evaluate the dynamic processes within cell tissue.The transport of Pickering emulsions in skeletal muscle tissue is specifically investigated as a case study.Various factors impacting the transport process are explored,including local cellular tissue environmental factors and the properties of the Pickering emulsion itself.The simulation results primarily demonstrate that an increase in radial repulsive interaction between emulsion particles can decrease the transport efficiency.Additionally,larger intercellular gaps also diminish the transport efficiency of emulsion droplet particles due to the increased motion complexity within the intricate transport space compared to a single channel.This study sheds light on the nuanced interplay between engineered and biological systems influencing the transport dynamics of Pickering emulsions.Such insights hold valuable potential for optimizing transport processes in practical biomedical applications such as drug delivery.Importantly,the desired transport efficiency varies depending on the specific application.For instance,while a more rapid transport might be crucial for lymph-node-targeted drug delivery,certain applications requiring a slower release of active components could benefit from the reduced transport efficiency observed with increased particle repulsion or larger intercellular gaps.

Rhein-based Pickering emulsion for hepatocellular carcinoma:Shaping the metabolic signaling and immunoactivation in transarterial chemoembolization

The efficacy of transarterial chemoembolization(TACE)has been limited by insufficient embolization and a high incidence of tumor recurrence.Herein,we iden-tified that aberrant metabolic reprogramming and immunosuppression contribute to TACE refractoriness and Rhein,as a potential glycolytic metabolism inhibitor and immunoactivation inducer,was optimized to sensitize tumors to TACE therapy.To achieve efficient embolization,we developed an oil-in-water lipiodol embolic emulsion by stabilizing the self-assembled Rhein nanogel.The assembled Rhein exhibited a nanofiber network,and its integration enhanced the mechanical stability and viscoelasticity of the lipiodol embolic agent.With the synergistic advantages of solid and liquid embolic agents,this carrier-free Pickering emulsion exhibits effi-cient embolization and sustained drug release in models of unilateral renal artery embolization,rabbit ear tumor embolization,rabbit orthotopic liver cancer,and rat orthotopic liver cancer.Compared to conventional three-way catheter mixing meth-ods,multimodal imaging corroborates a marked enhancement in local drug retention and tumor suppression.Importantly,the incorporation of Rhein-mediated syner-gistic immunoembolization in this strategy achieved efficient embolization while robustly activating anti-tumor immune responses,including inducing immunogenic cell death,dendritic cell activation,and major histocompatibility complex class I pre-sentation to CD8+T cells for tumor killing.Together,thesefindings reveal a novel strategy for the application of self-assembled Rhein nanofiber-stabilized lipiodol emulsion to control metabolic signaling and immunoactivation in TACE.

The use of bacterial cellulose from kombucha to produce curcumin loaded Pickering emulsion with improved stability and antioxidant properties

Curcumin is a bioactive molecule with limited industrial application because of its instability and poor solubility in water.Herein,curcumin-loaded Pickering emulsion was produced using purified bacterial cellulose from fermented kombucha(KBC).The morphology,particle size,stability,rheological properties,and antioxidant activities of the curcumin-loaded Pickering emulsion were investigated.The fluorescence microscope and scanning electron microscopy images showed that the curcumin-loaded Pickering emulsion formed circular droplets with good encapsulation.The curcumin-load Pickering emulsion exhibited better stability under a wide range of temperatures,low p H,sunlight,and UV-365 nm than the free curcumin,indicating that the KBC after high-pressure homogenization improved the stability of the CPE.The encapsulated curcumin retained its antioxidant capacity and exhibited higher functional potential than the free curcumin.The study demonstrated that the KBC could be an excellent material for preparing a Pickering emulsion to improve curcumin stability and antioxidant activity.

Current Trends in Pickering Emulsions: Particle Morphology and Applications

In recent years,Pickering emulsions and their applications have attracted a great deal of attention due to their special features,which include easy preparation and enhanced stability.In contrast to classical emulsions,in Pickering emulsions,solid microparticles or nanoparticles that localize at the interface between liquids are used as stabilizers,instead of surfactants,to enhance the droplet lifetime.Furthermore,Pickering emulsions show higher stability,lower toxicity,and stimuli-responsiveness,compared with emulsions that are stabilized by surfactants.Therefore,they can be considered attractive components for various uses,such as photocatalysis and the preparation of new materials.Moreover,the nanoparticle morphology strongly influences Pickering emulsion stability as well as the potential utilization of such emulsions.Here,we review recent findings concerning Pickering emulsions,with a particular focus on how the nanoparticles morphology(i.e.,cube,ellipsoid,nanosheet,sphere,cylinder,rod,peanut)influences the type and stability of such emulsions,and their current applications in different fields such as antibacterial activity,protein recognition,catalysis,photocatalysis,and water purification.

Recent studies of Pickering emulsion system in petroleum treatment:The role of particles

Pickering emulsions stabilized by solid particles have gained much attention,which afford high stability,low toxicity,controllable rheological properties and stimuli-responsive behavior compared to the traditional emulsions emulsified by surfactants.Those particles,as the core parts of the emulsion systems,play an important role in the fabrication and application of Pickering emulsion systems,making them attractive in petroleum fields.In this review,the influence of various particles on the stability and properties of Pickering emulsion systems as well as recent researches associated with the stimuliresponsibility of Pickering emulsion systems are introduced.Specifically,the design of functional particles and Pickering emulsion systems with super stabilities and controllable rheological properties are listed.Furthermore,some petroleum application of Pickering emulsion systems for enhanced oil recovery and spilled oil collection as well as the application as soft templates to fabricate oil-absorbing material and as three-phase microreactors that most likely for petroleum application are discussed,and the issues hindering the actual application of Pickering emulsion systems are also evaluated.This review charts a way for Pickering emulsion studies that could lead to a valid petroleum application through design of the particles served as the enhancers of Pickering emulsion stability for purpose of tailoring chemical flooding.

A CO_(2)/N_(2)-Responsive Pickering Emulsion Stabilized by Novel Switchable Surface-Active Alumina Nanoparticles

This article reports the development of a novel switchable Pickering emulsion with rapid CO_(2)/N_(2) respon-siveness,which is stabilized using alumina nanoparticles hydrophobized in situ with a trace amount of a switchable superamphiphile via electrostatic interactions.With the introduction of CO_(2) for 30 s,the Pickering emulsion can be spontaneously demulsified with complete phase separation;the emulsion can then be reconstructed in response to N_(2) purging for 10 min followed by homogenization.Moreover,the stable Pickering emulsion can be stored for more than 60 days at room temperature with-out any visible change.The CO_(2)/N_(2)-responsive behavior of the switchable Pickering emulsion is attribu-ted to the reversible desorption/adsorption of the switchable surfactants on the surfaces of the alumina nanoparticles upon the alternative bubbling of CO_(2)or N_(2).Thanks to the simple fabrication of the surfac-tant and the hydrophobization of the alumina nanoparticles,this research has developed an extremely facile and cost-efficient method for preparing a rapidly CO_(2)/N_(2)-responsive switchable Pickering emul-sion.The dosage of the switchable surfactants has been significantly reduced by nearly 1500 times(from 150 to 0.1 mmol·L^(-1))as compared with the dosage used in previous studies.Moreover,the as-prepared CO_(2)/N_(2)-responsive switchable Pickering emulsion is environmentally friendly,mild,and nontoxic;thus,it holds great potential for practical applications with considerable economic and environmental benefits,such as oil transport,fossil fuel production,environmental gases detection,and the encapsulation and release of active ingredients.

Effects of Water-Soluble Co-Solvent on Properties of W/O Pickering Emulsions

Effects of water-soluble co-solvents （WSCs）on the properties of water/oil Picketing emulsions were investigated. Picketing emulsions were prepared in the system of 1,2,4-trimethylbenzene （TMB）/hydrophobic sil- ica/water with varied concentrations of WSCs （ethanol, acetic acid and glycerin）. Mean droplet diameter distribu- tions of the obtained emulsions were studied to investigate the effects of WSCs types and concentrations. The results demonstrated that mean droplet diameter distributions decreased at first and then increased with the increase of WSC concentration. Moreover, the effect of WSC concentration on the phase inversion locus was further investi- gated. At the same time, infrared radiation （IR）spectrometer was used to investigate the mechanism. The results showed that the WSC attaching on hydrophobic silica changed the wettability of the particles, which facilitated the formation and phase inversion of the emulsion. The hydrogen bonds between the co-solvent groups attaching on the solid particles made a great effect on the droplet size of the emulsion and strengthened the interaction among emulsifiers. Overall, proper WSC was in favor of the stability of Picketing emulsion.

Preparation of Pickering Emulsion for Antibacterial, Anti-Inflammatory and Wound Healing

In recent years, natural biodegradable nanoparticles as stabilizers of Pickering emulsions have attracted extensive attention. In this work, a Pickering emulsion composed of chitosan/Arabic gum nanoparticles (CS/GA NPs), tea tree oil and vitamin E was formulated. Then the antibacterial, anti-inflammatory and wound healing abilities of the emulsion were evaluated. Pickering emulsion encapsulated the tea tree oil strengthened antibacterial activity towards Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. Besides, this multi-phase system offered a platform to load with vitamin E, which provides anti-inflammatory effects while antibacterial. Meanwhile, Pickering emulsion avoided contact between bacteria and skin when used in wound treatment.

Electrostatic Complexes of Nano-Montmorillonite/Ethyl Lauroyl Arginate Stabilized Sunflower Oil Pickering Emulsions

Compared with traditional surfactant-stabilised emulsions, Pickering emulsions, stabilised by clay nanoparticles, have the advantages of strong interface stability, strong versatility, and low toxicity. Moreover, they have excellent application potential in the fields of food and medicine. In this study, a food-grade Pickering emulsion stabiliser was prepared by physically adsorbing the cationic surfactant ethyl lauroyl arginate (LAE) on the surface of nano-montmorillonite (NMMT). Different LAE/NMMT combinations were assessed for their capacity to stabilise an oil-in-water emulsion at a low solid concentration (0.5%, w/v). The controllability of the droplet diameter and stability of the Pickering emulsions can be realised by changing the content of LAE. Scanning electron microscopy (SEM), and laser confocal microscopy (CLSM) confirmed the successful preparation of sunflower oil Pickering emulsion droplets stabilised by LAE/NMMT (0.0075%/1%). Additionally, the LAE/NMMT studied in this work could be used as a highly effective antibacterial surfactant with inorganic nanoparticles to efficiently stabilise Pickering emulsions, thus expanding the potential of preparing edible Pickering emulsion formulae.

The Application of Cellulose Nanocrystals in Pickering Emulsion as the Particle Stabilizer

Pickering emulsions stabilized by solid particles have attracted considerable interest by the food,pharmaceutical,and cosmetic industries.Cellulose nanocrystals(CNCs),with their high aspect ratio,renewability,degradability and biocompatibility,proved to be excellent Pickering stabilizers.This paper will initially review the purification and extraction methods used for targeted cellulose nanocrystals.This will be followed by a discussion of factors influencing the stability of Pickering emulsions containing cellulose nanocrystals.The applications of Pickering emulsions stabilized with cellulose naocrystals will be briefly discussed as well as research ideas for their future uses.

Bacterial microcompartment-mimicking Pickering emulsion droplets for detoxification of chemical threats under sweet conditions

Chemical warfare agents represent a severe threat to mankind and their efficient decontamination is a global necessity.However,traditional disposal strategies have limitations,including high energy consumption,use of aggressive reagents and generation of toxic byproducts.Here,inspired by the compartmentalized architecture and detoxification mechanism of bacterial microcompartments,we constructed oil-in-water Pickering emulsion droplets stabilized by hydrogen-bonded organic framework immobilized cascade enzymes for decontaminating mustard gas simulant(2-chloroethyl ethyl sulfide,CEES)under sweet conditions.Two exemplified droplet systems were developed with two-enzyme(glucose oxidase/chloroperoxidase)and threeenzyme(invertase/glucose oxidase/chloroperoxidase)cascades,both achieving over 6-fold enhancement in decontamination efficiency compared with free enzymes and>99% selectivity towards non-toxic sulfoxide.We found that the favored mass transfer of sugars and CEES from their respective phases to approach the cascade enzymes located at the droplet surface and the facilitated substrate channeling between proximally immobilized enzymes were key factors in augmenting the decontamination efficacy.More importantly,the robustness of immobilized enzymes enabled easy reproduction of both the droplet formation and detoxification performance over 10 cycles,following long-term storage and in far-field locations.

Photothermal phase change material microcapsules via cellulose nanocrystal and graphene oxide co-stabilized Pickering emulsion for solar and thermal energy storage

Phase change materials(PCMs)have attracted significant attention in thermal management due to their ability to store and release large amounts of heat during phase transitions.However,their widespread application is restricted by leakage issues.Encapsulating PCMs within polymeric microcapsules is a promising strategy to prevent leakage and increase heat transfer area with matrices.Moreover,photothermal PCM microcapsules are particularly desirable for solar energy storage.Herein,we fabricated photothermal PCM microcapsules with melamine-formaldehyde resin(MF)as shell using cellulose nanocrystal(CNC)and graphene oxide(GO)co-stabilized Pickering emulsion droplets as templates.CNC displays outstanding Pickering emulsifying ability and can facilitate the fixation of GO at the oil-water interface,resulting in a stable CNC/GO co-stabilized PCM Pickering emulsion.A polydopamine(PDA)layer was coated in-situ on the emulsion droplets via oxidization self-polymerization of dopamine.Meanwhile,GO was reduced to reduced GO(rGO)due to the reducing ability of PDA.The outmost MF shell of the PCM microcapsules was formed in-situ through the polymerization and crosslinking of MF prepolymer.The resulted PCM@CNC/rGO/PDA/MF microcapsules exhibit uniform sizes in the micrometer range,excellent leakage-proof performance,high phase change enthalpy(175.4 J g^(−1))and PCM encapsulation content(84.2%).Moreover,the presence of rGO and PDA endows PCM@CNC/rGO/PDA/MF microcapsules with outstanding photothermal conversion performance.The temperature of PCM@CNC/rGO/PDA/MF microcapsule slurries(15wt.%)can reach 73°C after light irradiation at 1 W cm^(−2).Therefore,photothermal PCM@CNC/rGO/PDA/MF microcapsules are promising for solar energy harvesting,thermal energy storage,and release in various applications,such as energy-efficient buildings and smart textiles.

The effect of Pickering emulsion adjuvants on the immune efficacy of the COVID-19 polypeptide vaccine

Pickering emulsions were prepared by phacoemulsification in an ice water bath with squalene as the oil phase and an aluminum adjuvant as the particle stabilizer.The effects of formulation and process conditions on the size and distribution of the Pickering emulsions were investigated.Pickering emulsions prepared under the optimal prescription and process conditions were mixed with a peptide antigen to obtain a peptide vaccine.The optimal prescription and process condition of the Pickering emulsion is as follows:squalene as the oil phase,ultra-pure water as the water phase with 5 mg/mL aluminum adjuvant,and an ultrasonication time of 4 min at 200 W power.BALB/c mice were immunized with the peptide vaccine,and the ability of the Pickering emulsion as an immunological adjuvant to improve the efficacy of the peptide vaccine was evaluated.Under optimal conditions,a Pickering emulsion with a small particle size(430.8 nm),uniform distribution(polydispersion index of 16.9%),and zeta potential of 31.5 mV,was obtained.Immunological results showed that the serum specific antibody level in the vaccinated group reached 1×104 after three immunizations.The proportion of CD4+T cells and CD4/CD8 cells was significantly higher(P<0.05)in the vaccinated groups than the blank control group.Further,cytokine(TNF-𝛼)secretion decreased in the aluminum adjuvant and Pickering emulsion groups but increased in the Freund’s adjuvant group.All three vaccinated groups of mice exhibited low but detectable levels of IFN-𝛾secretion.

Pickering emulsions stabilized by colloidal surfactants:Role of solid particles

Pickering emulsions are emulsions stabilized by colloidal surfactants,i.e.solid particles.Compared with traditional molecular suffactant-stabilized emulsions,Pickering emulsions show many advantages,such as high resistance to coalescence,long-term stability,good biocompatibility and tunable properties.In recent years,Pickering emulsions are widely applied in scientific researches and industrial applications.In this review,we focus on the influences of particle properties on Pickering emulsions,including particle amphiphilicity,concentration,size and shape,and summarize the strategies developed for the preparation of amphiphilic Janus particles.The applications of Pickering emulsions in food industry,cosmetic industry,material science,drug delivery,biomedical research and vaccine adjuvant will also be covered.Pickering emulsions are a unique system for multi-disciplinary studies and will become more and more important in the future.

A pH-responsive TiO_2-based Pickering emulsion system for in situ catalyst recycling

Developing methods for efficient product/catalyst separation and catalyst recycling is meaningful in multi-phase catalytic reactions. Here, we reported a p H-responsive emulsion system stabilized by interfacially active TiO2 nanoparticles for achieving in situ product/catalyst separation and catalyst recycling. In this system, emulsification and demulsification process could be easily engineered through tuning the p H values. The emulsion droplets were destroyed completely at a p H value of 3–4, and the solid catalyst distributed in the aqueous phase could be used to the next reaction cycle after removal of the organic product and adjusting the p H to 7–8. Such a p H triggered switchable Pickering emulsion catalytic system not only shows good recyclability of the solid catalyst but also high catalytic efficiency,and could be recycled more than 10 cycles.

Study of Pickering emulsions stabilized by mixed particles of silica and calcite

Picketing emulsions were prepared using mixed particles of silica and calcite as emulsifiers. The effects of the silica content in the mixed particles on the stability and the drop size of the Picketing emulsions were investigated. The results showed that the Picketing emulsions were of the oil-in-water type. With increasing silica content in the mixed partides, the stability and the drop size of the Pickering emulsions decreased. Larger silica particles had more influence on the stability of the emulsions, while smaller ones had more influence on the drop size of the emulsions. The effect of the silica particles on the emulsions was attributed to their adsorptive behavior at the oil-water interfaces of the Picketing emulsions.

Effect of Solvophilic Chain Length in PISA Particles on Pickering Emulsion

The morphology of polymeric nanoparticles prepared by polymerization-induced self-assembly(PISA)is depended on the degree of polymerization of the solvophilic and solvophobic blocks.Herein,a series of poly(N,N-dimethylaminoethyl methacrylate)-b-poly(benzyl methacrylate)(PDMA-b-PBzMA)diblock copolymer spherical nanoparticles were synthesized via reversible addition-frag-mentation chain transfer(RAFT)mediated PISA.These diblock copolymer nanoparticles are with nearly the same hydrodynamic size and solvophobic chain length,but with different solvophilic chain length.We used these nanoparticles to stabilize the oil-in-water Pickering emulsion.We find that the stability of Pickering emulsion increases with the length of solvophilic chain of the nanoparticles.Moreover,the droplet size of the Pickering emulsion can be tailored by varying the oil/water ratio and concentration of nanoparticles.

Pickering emulsions stabilized by biocompatible particles:A review of preparation,bioapplication,and perspective

The phenomenon of adsorption of solid particles at fluid interfaces to stabilize emulsions or foams have been known for more than a century.Today,particle-stabilized emulsions,often referred to as Pickering emulsions,are receiving growing attention as they are encountered in oil recovery and have long been used in personal care products and food industry.Over the past 10 years the focus of the Pickering emulsion has also increasingly shifted to biomedical applications with thanks to novel syntheses of a wide range of biocompatible particle stabilizers.Here,a brief overview of the development of biocompatible particles is given for Pickering emulsion stabilization,including alginate,poly(lactic-co-gIycolic acid)(PLGA),and protein-based particles.The materials prepared by templating from emulsion stabilized with biocompatible particles include colloidal capsules and hierarchically porous materials.It is hoped that the understanding gained from the recent intense activity in the field will enable more researchers to modify existing materials and design new formulations,which would be beneficial for exploring more biological applications.

Polyphosphoester-modified Cellulose Nanocrystals for Stabilizing Pickering Emulsion Polymerization of Styrene

The structure and properties of functional nanoparticles are important for stabilizing Pickering emulsion polymerization.Recently,cellulose nanocrystals(CNCs)are increasingly favored as a bio-based stabilizer for Pickering emulsions.In this study,we reported a novel functionalized polyphosphoester-grafted CNCs for the stabilization of oil-in-water Pickering emulsions and the emulsion polymerization of styrene.First,polyphosphoester containing an amino group at one end of the chain,abbreviated as PBYP-NH2,was prepared by ring-opening polymerization(ROP)and hydrolysis reaction,wherein PBYP represents poly[2-(but-3-yn-1-yloxy)-2-oxo-1,3,2-dioxaphospholane].Subsequently,CNC-COOH was obtained via 2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO)oxidation of CNCs.The functionalized nanocrystals CNC-PBYP-COOH with carboxyl groups and polyphosphoester on the surface were obtained by the amidation reaction of PBYP-NH2 with CNC-COOH.Finally,we used CNC-PBYP-COOH as sole particle emulsifiers to stabilize styrene-in-water Pickering emulsions and studied its effects on the emulsions in details by using dynamic light scattering(DLS).The results indicated that the properties of these emulsions depended on the concentration of hydrophobically modified CNCs,volume ratios of oil to water,and pH values.The modified CNCs had higher ability to stabilize the styrene-in-water emulsions relative to the unmodified CNCs,and a stable oil-in-water(o/w)Pickering emulsion with diameter of hundreds of nanometers could be obtained.The resulting emulsions could be polymerized to yield nanosized latexes.The polyphosphoester-modified CNCs as green particle emulsifiers can efficiently stabilize nanoemulsions and latexes,which would promote the development of novel environmentally friendly materials.