Fabrication and characterization of novel β-sitosterol-loaded O/W Pickering emulsions stabilized by edible insects protein/chitosan complex coacervates: Retention and stability evaluation.

Impact of surface-modified silica nanoparticle and surfactant on the stability and rheology of oil-in-water Pickering and surfactant-stabilized emulsions under high-pressure and high-temperature

BackgroundEugenol, an important active ingredient in essential oils, effectively inhibits food‐borne pathogens but is hindered by its high volatility. Pickering emulsion provides a suitable method to encapsulate, protect and enhance the absorption of these biologically active food components. This study investigated the encapsulation of different concentrations of eugenol Pickering emulsion stabilized with self‐assembled chitosan nanoparticles by ultrasound‐assisted emulsification. The effects of varying eugenol concentrations on Pickering emulsions' physical, stability, antioxidant and antimicrobial properties were analyzed.ResultsThe integration of eugenol at different concentrations increased the droplet size of Pickering emulsion, and the value ranged from 20 to 142 nm during a 60‐day storage. Eugenol (5%) significantly improved the antioxidant activity of the Pickering emulsion with a DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) value of 78%. In addition, eugenol effectively increased the antimicrobial activity of the Pickering emulsion against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) with inhibition zones of 14.1 and 17 mm, respectively. The stability of the Pickering emulsion increased with the increase in eugenol concentration throughout the storage period.ConclusionPickering emulsions stabilized with self‐assembled chitosan nanoparticles effectively enhanced the stability, antioxidant, and antimicrobial performance of eugenol. These results highlight the potential of such systems as natural and efficient delivery platforms for food and pharmaceutical applications. © 2025 Society of Chemical Industry (SCI).

pH-switchable pickering emulsions stabilized by polyelectrolyte-biosurfactant complex coacervate colloids

Effects of high-energy emulsification methods and environmental stresses on emulsion stability and retention of tocotrienols encapsulated in Pickering emulsions

Stabilization of Pickering emulsions by oxidized starch/zein nanoparticle complexes

CO2-switchable emulsion with controllable stability and viscosity based on chitosans and cetyltrimethylammonium bromide

Comparative characterization of the zein/propylene glycol alginate nanoparticles prepared by complex coacervation in aqueous ethanol.

Biodegradable Pickering emulsions of Lipiodol for liver trans-arterial chemo-embolization

Chitin nanocrystals (ChN) are insoluble particles that can be used as stabilizers for Pickering emulsions. Their unique cationic properties and antibacterial activity have generated considerable interest among researchers. However, ChN have remained largely underexplored. Furthermore, the droplets of the emulsions stabilized by ChN are as large as 10-100 μm, and their physical stability requires further improvement. Some studies have shown that the spontaneous reaction of oppositely charged particles can effectively stabilize the emulsions. Positively charged ChN and negatively charged fucoidan (F) were therefore compounded to stabilize Pickering emulsions, and the stability of these emulsions was analyzed qualitatively. The results showed that the composite particles comprising two polysaccharides in a mass ratio of 1:1 and at a pH of 2 (ChN1 -F1 -pH 2) possessed the lowest sulfate content (20.1%) and almost zero potential (-3 mV), indicating a high degree of neutralization of the positively charged amino group in ChN and the negatively charged sulfate group in F. Meanwhile, ChN1 -F1 -pH 2 displayed a dense network structure that improved the dispersibility and wettability (contact angle = 9.3°). Fourier transform infrared spectroscopy results confirmed that ChN and F were effectively combined through electrostatic interaction or neutralization to produce a polyelectrolyte complex. Furthermore, the particle size of the Pickering emulsion stabilized by ChN-F was significantly reduced, and the maximum size did not exceed 10 μm; the physical and storage stability also improved. The ChN1 -F1 -pH 2 emulsion presented excellent storage stability; in particular, the emulsions stabilized by ChN1 -F1 -pH 5 and ChN1 -F1 -pH 6 exhibited excellent flocculation stabilities. The size of the emulsion droplets stabilized by the oppositely charged polysaccharide particles (ChN-F complexes) reduced significantly. Furthermore, by changing the mass ratio and pH, the microstructure and binding degree of the complexes can be adjusted, thereby promoting their adsorption on the oil-water interface and improving the stability of the Pickering emulsion. © 2020 Society of Chemical Industry.

Influence of charged polysaccharides and zein nanoparticles on the interfacial and emulsification properties of Pickering emulsions

Stabilization of emulsions with solid particles can be used in several fields of oil and gas industry because of their higher stability. Solid particles should be amphiphilic to be able to make Pickering emulsions. This goal is achieved by using surfactants at low concentrations. Oil-in-water (o/w) emulsions are usually stabilized by surfactant but show poor thermal stability. This problem limits their applications at high-temperature conditions. In this study, a novel formulation for o/w stabilized emulsion by using silica nanoparticles and the nonionic surfactant is investigated for the formulation of thermally stable Pickering emulsion. The experiments performed on this Pickering emulsion formula showed higher thermal stability than conventional emulsions. The optimum wettability was found for DME surfactant and silica nanoparticles, consequently, in that region; Pickering emulsion showed the highest stability. Rheological changes were evaluated versus variation in surfactant concentration, silica concentration and pH. Scanning electron microscopy images approved the existence of a rigid layer of nanoparticle at the oil-water interface. Finally, the results show this type of emulsion remains stable in harsh conditions and allows the system to reach its optimum rheology without adding any further additives.

Solid particle-stabilized Pickering emulsions can be used as alternative reaction systems, for example, for the homogeneously catalyzed hydroformylation reaction. This study addresses the understanding of the physicochemical behavior of Pickering emulsions in terms of the hydroformylation in a recycable process. In the first part (see chapter 4), fumed silica with different hydrophobicities were used to stabilize the emulsions. Hence, the droplets with W/O Pickering emulsions exhibit a size that is a function of particle concentration and energy input during the preparation. Furthermore, adsorption of interface impurities on the particles is observed, resulting in an increase of the interfacial tension. In addition, the Pickering emulsions are highly stable in a batch reactor. Hence, the hydroformylation reaction in Pickering emulsions was optimized and a complete recycling cycle with a membrane filtration was successfully demonstrated. In chapter 5, hydrophilic particles with different particle shapes, so-called Halloysite nanotubes and fumed silica, which stabilize an O/W Pickering emulsion were used due to higher conversions. The larger Halloysite nanotubes initially exhibit an isotropic interface orientation that converts to a radial configuration by increasing the particle concentration. It was possible to modify the Halloysite nanotubes, but the change in wettability was not strongly pronounced. Furthermore, emulsions stabilized by pristine Halloysite nanotubes or by silica show a dependency on the particle concentration, hence, in the case of Halloysite nanotubes, the droplet size does not decrease monotonically. The addition of the interface-active Rh-catalyst leads to a droplet size in the order of nanometers, resulting in droplets without adherent particles. The increase in the droplet size to the micrometer scale leads to an adherence of the particles. Thus, a corresponding model of Pickering emulsions is postulated in a batch reactor, with intermediate emulsion stability promoting the reaction. The last chapter (see chapter 6) investigates the interaction between positively charged particles and the negatively charged rhodium (Rh-) catalyst in terms of emulsion structure and hydroformylation. The positively charged polystyrene particles used stabilize a W/O emulsion while the modified positively charged Halloysite nanotubes stabilize an O/W emulsion. It is shown that the Rh-catalyst adsorbs at the particle surface, which does not change the emulsion type. Further, in the case of polystyrene-stabilized Pickering emulsions, the particle density at the interface is also not affected by the adsorption of the Rh-catalyst. However, the diffusion behavior of the polystyrene particles at the interface is influenced by the adsorption of the Rh-catalyst on the particle surface. In general, it is demonstrated that the positive surface charge for both particle types leads to a higher conversion and selectivity in comparison to their negatively charged analogous.

Pickering emulsions are multiphasic liquid mixtures that are stabilized by solid particles. The strong attachment of particles to the interface makes these emulsions very stable. Additional functionality can be imparted to the emulsion by using particles with useful catalytic, electrical, photonic and magnetic properties. We highlight the most recent developments in polymer colloid-stabilized Pickering emulsions. Pickering emulsions are compared to conventional emulsions that are stabilized by molecular surfactants, focusing on the difference in thermodynamics of the formation of these two different emulsions. Pickering emulsions stabilized with anisotropic polymer particles with homogenous compositions, such as ellipsoids, microrods and thin sheets, are discussed in the second section. In the third section, we highlight recent advances in using Janus particles as solid surfactants for Pickering emulsions. The behavior of Janus particles at liquid–liquid interfaces, the thermodynamics of the formation of Pickering emulsions with Janus particles and the effect of Janus balance on emulsion stabilization are discussed. The fourth section discusses Pickering emulsions based on microgels, a unique class of polymer colloids. These microgels enable the preparation of stimuli-responsive Pickering emulsions as well as high internal phase emulsions for applications in cargo delivery and energy storage devices. The section highlights Pickering emulsions stabilized with polymer-grafted particles and recent developments in preparing Pickering emulsions stabilized by biopolymer colloids such as cellulose nanocrystals, proteins and fat crystals. The chapter concludes by presenting some of the outstanding questions that must be addressed to enable utilization of polymer colloids as effective and functional materials for emulsion stabilization.

The three levels of stabilization in pickering emulsions stabilized by a non-modified bentonite particle: from particle efficiency to emulsion stabilization efficiency.

Factors that affect Pickering emulsions stabilized by mesoporous hollow silica microspheres