Insights into the Evolution of an Emulsion with Demulsifying Bacteria Based on Turbiscan

Effects of solid lipid ratio in curcumin loaded emulsions on its gastrointestinal fate: Colloidal stability and mucus absorption efficiency

Emulsions offer a promising approach for enhancing the bioavailability of lipophilic active compounds when administered orally. Nonetheless, the impact of lipid matrix composition on the efficacy of penetration and bioavailability remains uncertain. This research investigated the effects of solid lipid ratio in emulsions on colloidal stability, mucus permeability, and bioavailability in vivo. To assess colloidal stability in the gastrointestinal tract (GIT), Turbiscan was employed. The results indicated that an elevated solid lipid ratio improved intestinal stability through the formation of aggregations that resisted pancreatic absorption, as confirmed by TEM. The absorption in various intestinal sections was tested using the Ussing Chamber model. Notably, emulsion with 0 % solid lipid (G0M10) exhibited the highest cumulative permeation across the duodenum (221.2 ± 21.19 ng), jejunum (713.1 ± 20.93 ng), and ileum (1056.3 ± 392.06 ng) due to its higher in vitro release rate (>60 %) and smaller particle size. The cumulative permeation decreased with increasing solid lipid ratio. CLSM revealed that emulsions with a solid lipid ratio exceeding 50 % exhibited poor mucus permeability within 15 min due to aggregation during the passage in the GIT. However, over an extended penetration time (30 min), higher permeability was observed, reaching approximately 30 μm. In vitro release studies indicated that a higher solid lipid ratio resulted in a reduced release rate of curcumin (<60 %) compared to G0M10 (66.9 ± 3.58 %). Correlation analysis unveiled a positive link between bioavailability and in vitro release rate, while a negative correlation emerged with the solid lipid ratio. This work underscores the significance of solid lipid ratios in emulsions for optimizing bioavailability through their influence on stability, permeability, and release of lipophilic compounds in the GIT.

Multiscale combined techniques for evaluating emulsion stability: A critical review

Emulsions are multiscale and thermodynamically unstable systems which will undergo various unstable processes over time. The behavior of emulsifier molecules at the oil-water interface and the properties of the interfacial film are very important to the stability of the emulsion. In this paper, we mainly discussed the instability phenomena and mechanisms of emulsions, the effects of interfacial films on the long-term stability of emulsions and summarized a set of systematic multiscale combined methods for studying emulsion stability, including droplet size and distribution, zeta-potential, the continuous phase viscosity, adsorption mass and thickness of the interfacial film, interfacial dilatational rheology, interfacial shear rheology, particle tracking microrheology, visualization technologies of the interfacial film, molecular dynamics simulation and the quantitative evaluation methods of emulsion stability. This review provides the latest research progress and a set of systematic multiscale combined techniques and methods for researchers who are committed to the study of oil-water interface and emulsion stability. In addition, this review has important guiding significances for designing and customizing interfacial films with different properties, so as to obtain emulsion-based delivery systems with varying stability, oil digestibility and bioactive substance utilization.

Formation and Stabilization of W1/O/W2 Emulsions with Gelled Lipid Phases

Water-in-oil-in-water (W₁/O/W₂) emulsions are emulsion-based systems where the dispersed phase is an emulsion itself, offering great potential for the encapsulation of hydrophilic bioactive compounds. However, their formation and stabilization is still a challenge mainly due to water migration, which could be reduced by lipid phase gelation. This study aimed to assess the impact of lipid phase state being liquid or gelled using glyceryl stearate (GS) at 1% (w/w) as well as the hydrophilic emulsifier (T80: Tween 80 or lecithin) and the oil type (MCT:medium chain triglyceride or corn oil (CO) as long chain triglyceride) on the formation and stabilization of chlorophyllin W₁/O/W₂ emulsions. Their colloidal stability against temperature and light exposure conditions was evaluated. Gelling both lipid phases (MCT and CO) rendered smaller W₁ droplets during the first emulsification step, followed by formation of W₁/O/W₂ emulsions with smaller W₁/O droplet size and more stable against clarification. The stability of W₁/O/W₂ emulsions was sensitive to a temperature increase, which might be related to the lower gelling degree of the lipid phase at higher temperatures. This study provides valuable insight for the formation and stabilization of W₁/O/W₂ emulsions with gelled lipid phases as delivery systems of hydrophilic bioactive compounds under common food storage conditions.

Destabilization mechanism of (W1+W2)/O reverse Janus emulsions

HYPOTHESIS

Reverse Janus emulsion, with droplets composed by "two rooms" of water phases, is a novel multiple emulsion attributed to excellent integration capability and biocompatibility. However, significant instability compared with normal Janus emulsions renders the stability issue of great importance. Moreover, the ultra-low aqueous-aqueous inner interfacial tension, the anisotropic nature of the droplets with distinct lobe composition, and the random orientation in the continuous phase endow the complicated and various demulsification mechanisms.

EXPERIMENTS

Reverse Janus emulsion of (W₁+W₂)/O, employing typical salt-alcohol aqueous two-phase system (ATPS) as inner phases, is prepared in batch scale by conventional one-step vortex mixing. The demulsification process is detected by multiple light scattering technique, which provides real-time, in-situ, and quantitative information of emulsion evolution. Moreover, the fusion pattern of the anisotropic droplets is illustrated by the combination with light microscopy and size distribution measurement.

FINDINGS

Coalescence and sedimentation are found to be two main demulsification processes. Two salt "body" lobes of the "snowman" shaped Janus droplets combine first resulting in an intermediate Cerberus topology with two alcohol "heads" on one salt "body". Subsequently, two "head" lobes coalesce resulting in a larger Janus droplet. Ultimately, the Gibbs free energy leads to a final state with three separated liquids. In addition, the variation in lobe viscosity, density, and properties of interfacial film greatly affect the demulsification rate and fusion pattern. A critical alcohol/surfactant mass ratio of 2 is found, beyond which a completely different fusion pattern occurs. Two alcohol "body" lobes combine first resulting in an intermediate Cerberus topology with two salt "heads" on one alcohol "body". Subsequently, two "head" lobes coalesce resulting in a larger Janus droplet. The findings are instructive in the stability of aqueous based multiple emulsions with advanced morphologies and meanwhile, promote the future application of this novel emulsion in food science, pharmacy, and biomimetic compartmentalization.

Structural stability of liposome-stabilized oil-in-water pickering emulsions and their fate during in vitro digestion

An interesting liposome-stabilized oil-in-water Pickering emulsion shows pH-controllable and surfactant-dependent deformability whilst displaying dual delivery routes under external environment and oral-gastrointestinal conditions.