Salt-induced thermal gelation of xyloglucan in aqueous media

Development and Characterization of Silibinin-Loaded Nanoemulsions: A Promising Mucoadhesive Platform for Enhanced Mucosal Drug Delivery

Background: Silibinin (SLB), a flavonoid derived from milk thistle, exhibits promising therapeutic properties but faces significant clinical limitations due to poor solubility and bioavailability. Objectives: This study focuses on the development and characterization of SLB-loaded nanoemulsions designed for mucosal delivery. Methods: Nanoemulsions were prepared using the spontaneous emulsification method, guided by pseudoternary phase diagrams to determine selected component ratios. Comprehensive characterization included particle size, polydispersity index (PDI), zeta potential, encapsulation efficiency, rheological properties, and surface tension. Mucoadhesive properties were evaluated using quartz crystal microbalance with dissipation (QCM-D) to quantify interactions with mucin layers. Results: The combination of Capryol 90, Tween 80, and Transcutol in selected proportions yielded nanoemulsions with excellent stability and solubilization capacity, enhancing the solubility of silibinin by 625 times compared to its intrinsic solubility in water. The ternary phase diagram indicated that achieving nanoemulsions with particle sizes between 100 and 300 nm required higher concentrations of surfactants (60%), relative to oil (20%) and water (20%), with formulations predominantly composed of Smix (surfactant and cosurfactant mixture in a 1:1 ratio). Rheological analysis revealed Newtonian behavior, characterized by constant viscosity across varying shear rates and a linear torque response, ensuring ease of application and mechanical stability. QCM-D analysis confirmed strong mucoadhesive interactions, with significant frequency and dissipation shifts, indicative of prolonged retention and enhanced mucosal drug delivery. Furthermore, contact angle measurements showed a marked reduction in surface tension upon interaction with mucin, with the SLB-loaded nanoemulsion demonstrating superior wettability and strong mucoadhesive potential. Conclusions: These findings underscore the suitability of SLB-loaded nanoemulsions as a robust platform for effective mucosal drug delivery, addressing solubility and bioavailability challenges while enabling prolonged retention and controlled therapeutic release.

Gel-forming polysaccharides of traditional gel-like foods: Sources, structure, gelling mechanism, and advanced applications

Gels are intermediates between solid and liquid with elastic and flowable characteristics whose three-dimensional networks can restrict water, air, and oil. They have extensive applications in modern times in biomedical engineering, electronics, environmental engineering, etc. However, gels have also been made as foods from ancient times for over a thousand years, such as pudding, tofu, and cheese. Among them, protein-based gel-like foods have continuously garnered significant attention and research. In contrast, some polysaccharide-based gel-like foods in southeast Asia, such as "liangfen", "green tofu", "ice jelly", "tamarind jelly", "konjac tofu", and "black grass jelly", have not been noticed until recent years regarding their compositions and gelling mechanisms. This review commences on six traditional gel-like foods mentioned above, which refer to six different types of plants and four kinds of gel-forming polysaccharides, including pectin, tamarind seed xyloglucan, konjac glucomannan, and Mesona chinensis polysaccharide. Recent progress and developments of these gel-forming polysaccharides on different gelling mechanisms are summarized. Due to differences in corresponding gel properties, these polysaccharides are applied in various fields, such as delivery systems, tissue engineering, wound dressings, and adsorbent materials. Future trends of these gels would potentially focus on manipulating the mechanical properties by modifying the flexibility of polysaccharide molecules and designing composite gels, as well as producing stimuli-responsive hydrogels and other desirable aspects to catch up with the properties of synthetic counterparts.

Gelling properties of lysine-amidated citrus pectins: The key role of pH in both amidation and gelation

The amidation of pectin by amino acids has been widely applied due to its safety and excellent gelling properties. This study systematically examined the effects of pH on the gelling properties of lysine-amidated pectin during amidation and gelation. Pectin was amidated over the range of pH 4-10, and the amidated pectin obtained at pH 10 showed the highest degree of amidation (DA, 27.0 %) due to the de-esterification, electrostatic attraction, and the stretching state of pectin. Moreover, it also exhibited the best gelling properties due to its greater numbers of calcium-binding regions (carboxyl groups) and hydrogen bond donors (amide groups). During gelation, the gel strength of CP (Lys 10) at pH 3-10 first increased and then decreased, with the highest gel strength at pH 8, which was due to the deprotonation of carboxyl groups, protonation of amino groups, and β-elimination. These results show that pH plays a key role in both amidation and gelation, with distinct mechanisms, and would provide a basis for the preparation of amidated pectins with excellent gelling properties. This will facilitate their application in the food industry.

Ultrasound-assisted extraction of tamarind xyloglucan: an effective approach to reduce the viscosity and improve the α-amylase inhibition of xyloglucan

BACKGROUND

Water extraction (WE) is the classical extraction method for tamarind xyloglucan (XyG), but its low yield, high viscosity and poor dispersion in aqueous solution are not conducive to the industrial applications. To promote the industrial application of tamarind XyG, an ultrasonic-assisted extraction (UAE) method for extracting low-viscosity XyG from tamarind kernel powder was proposed.

RESULTS

The yield of UAE-XyG was higher (502.33 ± 0.036 g kg^-1 ) than that of WE-XyG (163.43 ± 0.085 g kg^-1 ). UAE reduced the molecular weight, monosaccharide content and apparent viscosity of XyG. The hypoglycemic experiment in vitro showed that UAE-XyG had a stronger inhibitory effect on α-amylase activity than WE-XyG, but its glucose dialysis retardation index was lower.

CONCLUSION

In sum, UAE is a type of extraction method that could effectively improve the yield of XyG and reduce its viscosity to expand its application without reducing its physiological activity. UAE exhibits an excellent potential in the extraction of XyG. © 2022 Society of Chemical Industry.

pH-responsive in situ gelling properties of thiolated citrus high-methoxyl pectin and its potential gel mechanism

pH-responsive in situ gelling properties of thiolated citrus high-methoxyl pectin (TCHMP) were investigated in this study. The gelation capacity results revealed that the in situ gelation behavior of TCHMP only occurred when the pH value was higher than 6.25. The gel strength increased from 26.63 g to 42.77 g as the pH value increased from 7.4 to 8.9. Rheological measurements confirmed that the apparent viscosity and viscoelasticity of TCHMP were highly dependent on pH value and dialysis time. Compared with the control group, the apparent viscosity of TCHMP dialyzed in phosphate-buffered saline (PBS) of pH 8.9 for 180 min increased 695-fold. During the dialysis process of TCHMP at different pH values (7.4-8.9), the final thiol groups content decreased and the final disulfide bonds content increased with the increase in pH value. This illustrates that the mechanism of in situ gelation is mainly the oxidation of thiol-thiol groups to form disulfide bonds. These results can put forward new insights into the pH-responsive in situ gelling properties of TCHMP and provide a theoretical basis for the application of TCHMP in neutral and alkaline gel systems.

The gelation behavior of thiolated citrus high-methoxyl pectin induced by sodium phosphate dibasic dodecahydrate

The present study found that sodium phosphate dibasic dodecahydrate (Na₂HPO₄) was capable of inducing the gelation of thiolated citrus high-methoxyl pectin (TCHMP). TCHMP was synthesized by amidation of citrus high-methoxyl pectin. The gel formation exhibited an obvious concentration-dependence, including TCHMP and Na₂HPO₄ concentration. For Na₂HPO₄-induced TCHMP gels (TCHMPGs), gel strength and water holding capacity (WHC) increased, while the microcellular network structure was more compact with the increase of TCHMP and Na₂HPO₄ concentration. Dynamic viscoelastic experiment showed when Na₂HPO₄ concentration was more than or equal to 0.5 mol/L, TCHMP sols could be transferred into gels within 30 min. Crystal property was not changed while thermal stability was improved after phase transition. Gelling forces analysis indicated that disulfide bonds were the main interaction forces in TCHMPGs. Consequently, TCHMPGs were covalently crosslinked and exhibited satisfactory gel performance. The results provide a theoretical basis for the formation of gels by Na₂HPO₄ induced TCHMP.

In-situ gelling xyloglucan formulations as 3D artificial niche for adipose stem cell spheroids

Three-dimensional spheroidal cell aggregates of adipose stem cells (SASCs) are a distinct upstream population of stem cells present in adipose tissue, with enhanced regeneration properties in vivo. The preservation of the 3D structure of the cells, from extraction to administration, can be a promising strategy to ensure optimal conditions for cell viability and maintenance of stemness potential. With this aim, an artificial niche was created by incorporating the spheroids into an injectable, in-situ gelling solution of partially degalactosylated xyloglucan (dXG) and an ad hoc formulated culture medium for the preservation of stem cell spheroid features. The evolution of the mechanical properties and the morphological structure of this artificial niche was investigated by small amplitude rheological analysis and scanning electron microscopy, respectively. Comparatively, systems produced with the same polymer and the typical culture medium (DMEM) used for adipose stem cell (ASC) growth in adherent cell culture conditions were also characterised. Cell viability of both SASCs and ASCs incorporated inside the hydrogel or seeded on top of the hydrogel were investigated as well as the preservation of SASC stemness conditions when embedded in the hydrogel.

Synthesis and Evaluation of Cytocompatible Alkyne-Containing Poly(β-amino ester)-Based Hydrogels Functionalized via Click Reaction

Although poly(β-amino esters) (PAEs) have been widely applied in nonviral gene transfection, drug delivery systems, and regenerative medicine, the multifunctional modification of PAEs and bio-orthogonal strategies of PAE-based hydrogel functionalization is still a challenge. Herein, a strategy of poly(β-amino ester)-based hydrogel functionalization was developed via bio-orthogonal reactions in this study. Acrylate-terminated poly(β-amino esters) containing alkyne groups were synthesized by Michael addition reaction. Alkyne groups on poly(β-amino esters) could conjugate bioactive molecules with azide of K(N₃)RGD via copper-catalyzed azide-alkyne cycloaddition, and terminal acrylate groups could in situ polymerize to prepare a hydrogel. A biomimetic peptide K(N₃)RGD functionalized hydrogel was prepared by polymerization of acrylate-terminated poly(β-amino esters) containing conjugated peptide and polyethylene glycol diacrylate (PEGDA). The storage modulus and mechanical properties exhibited an increased trend with the increased concentration; nevertheless, swelling ratio and surface wetting properties demonstrated a decreased tendency by increased concentrations. Cell proliferation and live/dead staining showed that Schwann cells plated on the hydrogel with an elastic modulus of 25.39 KPa are more suitable for proliferation and function exertion of Schwann cells compared with that of 42.11 and 57.86 KPa, and KRGD-conjugated hydrogel could increase the elongation of Schwann cells relative to nonconjugated hydrogels. This azide-alkyne strategy may be a promising candidate for hydrogel functionalization in tissue engineering and other biomedical applications.

Simultaneous determination of interfacial molarities of an alcohol, bromide ion, and water during an alcohol induced microstructural transition: the difference between medium and long chain alcohols

The transitions between surfactant aggregate structures are triggered by changes in chemical or physical stimulations, including addition of additives. Effects of added alcohols on aggregate morphologies correlate strongly with alcohol chain length. The local molarities of alcohol, water, and counterions in the interfacial regions play an important role in controlling the aggregate morphologies. However, direct experimental estimates of changes of interfacial alcohol molarities during alcohol induced micelle-to-vesicle transitions have never been reported. Ellipsoidal-wormlike micelle-vesicle transitions in CTAB/KBr aqueous solutions in the presence of long-chain octanol were characterized by using combined rheological, dynamic light scattering (DLS), transmission electron microscopy (TEM) and turbidity measurements. However, the transitions are absent with added butanol. The chemical trapping method (CT) was employed to understand the differences between medium- and long-chain alcohols in determining aggregate morphology. The CT method was used to estimate interfacial water, alcohol, and counterion molarities with increasing stoichiometric alcohol concentrations. With 55 mM alcohol added, the interfacial octanol molarity is 0.9 M, which is three times higher than that for butanol. With added octanol, the ellipsoidal-wormlike micelle-vesicle transition is accompanied by a concurrent sharp increase of interfacial water molarities and a decrease of interfacial counterion molarity, which is not observed with added butanol. The CT data was also employed to estimate the changes of Israelachvili's packing parameter with increasing added alcohol concentration. Our result provides critical molecular level information for understanding the morphological transitions of CTAB/additives.