Structural and mechanical properties of biopolymer gels

Microemulsion-Based Polymer Gels with Ketoprofen and Menthol: Physicochemical Properties and Drug Release Studies

Ketoprofen is a non-steroidal, anti-inflammatory drug frequently incorporated in topical dosage forms which are an interesting alternatives for oral formulations. However, due to the physiological barrier function of skin, topical formulations may require some approaches to improve drug permeation across the skin. In this study, ketoprofen-loaded microemulsion-based gels with the addition of menthol, commonly known for absorption-enhancing activity in dermal products, were investigated. The main objective of this study was to analyze the physicochemical properties of the obtained gels in terms of topical application and to investigate the correlation between the gel composition and its mechanical properties and the drug release process. Microemulsion composition was selected with the use of a pseudoternary plot and the selected systems were tested for electrical conductivity, viscosity, pH, and particle diameter. The polymer gels obtained with Carbopol® EZ-3 were subjected to rheological and textural studies, as well as the drug release experiment. The obtained results indicate that the presence of ketoprofen slightly decreased yield stress values. A stronger effect was exerted by menthol presence, even though it was independent of menthol concentration. A similar tendency was seen for hardness and adhesiveness, as tested in texture profile analysis. Sample cohesiveness and the drug release rate were independent of the gel composition.

Study and evaluation of a gelatin- silver oxide nanoparticles releasing nitric oxide production of wound healing dressing for diabetic ulcer

This study aimed to develop a novel Gelatin silver oxide material for releasing nitric oxide bionanocomposite wound dressing with enhanced mechanical, chemical, and antibacterial properties for the treatment of diabetic wounds. The gelatin- silver oxide nanoparticles (Ag2O-NP) bio nanocomposite was prepared using chitosan and gelatin polymers incorporated with silver oxide nanoparticles through the freeze-drying method. The samples were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Results showed that the Ag2O-NP nanoparticles increased porosity, decreased pore size, and improved elastic modulus. The Ag2O-NP wound dressing exhibited the most effective antibacterial properties against Staphylococcus aureus and Escherichia coli. Among the samples, the wound dressing containing silver oxide nanoparticles demonstrated superior physical and mechanical properties, with 48% porosity, a tensile strength of 3.2 MPa, and an elastic modulus of 51.7 MPa. The fabricated wound dressings had a volume ratio of empty space to total volume ranging from 40% to 60%. In parallel, considering the complications of diabetes and its impact on the vascular system, another aspect of the research focused on developing a per2mediated wound dressing capable of releasing nitric oxide gas to regenerate damaged vessels and accelerate diabetic wound healing. Chitosan, a biocompatible and biodegradable polymer, was selected as the substrate for the wound dressing, and beta-glycerophosphate (GPβ), tripolyphosphate (TPP), and per2mediated alginate (AL) were used as crosslinkers. The chitosan-alginate (CS-AL) wound dressing exhibited optimal characteristics in terms of hole count and uniformity in the scanning electron microscope test. It also demonstrated superior water absorption (3854%) and minimal air permeability. Furthermore, the CS-AL sample exhibited an 80% degradation rate after 14 days, indicating its suitability as a wound dressing. The wound dressing was loaded with S-nitrosoglutathione (GSNO) powder, and the successful release of nitric oxide gas was confirmed through the grease test, showing a peak at a wavelength of 540 nm. Subsequent investigations revealed that the treatment of human umbilical vein endothelial cells (HUVECs) with high glucose led to a decrease in the expression of PER2 and SIRT1, while the expression of PER2 increased, which may subsequently enhance the expression of SIRT1 and promote cell proliferation activity. However, upon treatment of the cells with the modified materials, an increase in the expression of PER2 and SIRT1 was observed, resulting in a partial restoration of cell proliferative activity. This comprehensive study successfully developed per2-mediated bio-nanocomposite wound dressings with improved physical, mechanical, chemical, and antibacterial properties. The incorporation of silver oxide nanoparticles enhanced the antimicrobial activity, while the released nitric oxide gas from the dressing demonstrated the ability to mitigate vascular endothelial cell damage induced by high glucose levels. These advancements show promising potential for facilitating the healing process of diabetic wounds by addressing complications associated with diabetes and enhancing overall wound healing.

Multi-crosslinked hydrogel built with hyaluronic acid-tyramine, thiolated glycol chitosan and copper-doped bioglass nanoparticles for expediting wound healing

The migration of fibroblasts and endothelial cells is a critical determinant of wound-healing outcomes for skin injuries. Here, hyaluronic acid-tyramine (HAT) and thiolated glycol chitosan (TGC) conjugates were combined with copper-doped bioglass (ACuBG) nanoparticles to build a novel type of multi-crosslinked hydrogel for stimulating the migration of cells, and thus, expediting wound healing. The optimally devised HAT/TGC/ACuBG gels had markedly improved strength and stiffness compared to the gels built from either HAT or TGC while showing sufficient elasticity, which contributes to stimulating the migration of fibroblasts. The sustainable release of silicon and copper ions from the gels was found to jointly induce the migration of human umbilical vein endothelial cells. The results based on mouse full-thickness skin defects demonstrated that they were able to fully restore the skin defects with formation of complete appendages within two weeks, suggesting their promising potency for use in expediting wound healing.

Assembly of soy protein-corn starch composite gels by thermal induction: Structure, and properties

The effect of different corn starch (CS) concentrations on the gel formation of soybean isolate protein (SPI) was investigated. Moreover, the texture, rheological properties of the gel were determined, and the spatial structure and interactions of the composite gel system were analyzed. The composite system transitioned from liquid to solid-like with an increase in the CS concentration and did not backflow when inverted for 24 h. With the addition of CS, the gel strength, water holding capacity (WHC), G', and G'' increased significantly. The maximum was reached at 10 % starch concentration with gel strength of (228.96 ± 29.86) g and WHC of (98.93 ± 2.02)  %. According to low-field 1H nuclear magnetic resonance (LF-NMR) results, CS has a high water absorption capacity, which improved the WHC. The scanning electron microscopy results revealed that composite gels with a high CS concentration had a more dense and small void network structure. According to the results of molecular force interaction, infrared spectroscopy, Raman spectroscopy, and free sulfhydryl group analysis, the added starch promoted the unfolding of SPI molecules, exposure of hydrophobic groups, transformation of free sulfhydryl groups into disulfide bonds, and hydrogen bond formation. Hydrophobic interactions, disulfide bonding, and hydrogen bonding function together to form the SPI-CS composite gel system. The study results provide the basis for applying soy protein and CS gels.

Strong, elastic and degradation-tolerated hydrogels composed of chitosan, silk fibroin and bioglass nanoparticles with factor-bestowed activity for bone tissue engineering

Polymer hydrogels intended for use in bone repair need to be strong, elastic, and capable of enduring degradation. However, many natural polymer hydrogels lack these essential properties and thus, are unsuitable for bone repair applications. Here, a new type of multi-network hydrogel with improved mechanical and degradation-resistant properties has been developed for use in bone repair. The hydrogel is composed of thiolated chitosan (TCH), silk fibroin (SF), and thiolated bioglass (TBG) nanoparticles (NPs). The multi-networks are built through sulfhydryl self-crosslinking, diepoxide crosslinker-involved linkages of amino or hydroxyl groups, and enzyme-mediated phenol hydroxyl crosslinking. Additionally, mesoporous TBG NPs serve as a vehicle for loading stromal cell-derived factor-1 (SDF-1) to provide the gel with cell-recruiting activity. The formulated TCH/SF/TBG hydrogels exhibit remarkably enhanced strength, elasticity, and improved degradation tolerance compared to some gels made from only TCH or SF. Furthermore, TCH/SF/TBG gels can support the growth of seeded cells and the deposition of matrix components. Some TCH/SF/TBG gels also demonstrate the ability to release SDF-1 in an approximately linear manner for a few weeks while retaining the chemotactic properties of the released SDF-1. Overall, the multi-network hydrogel has the potential as an in situ forming material for cell-recruiting bone repair and regeneration.

Ferulated Poly(vinyl alcohol) based hydrogels

New graft copolymers were prepared by reaction of poly (vinyl alcohol) (PVA) with mono-imidazolide or bis-imidazolide derivatives of ferulic acid (FA) with the formation of ester bonds. The obtained graft copolymers, thanks to the crosslinking capability of FA, formed in water strong gels as verified by rheological analyses. The resulting hydrogels were characterized to evaluate their applicability as wound dressing. In this perspective, their capability to absorb and retain a large amount of fluid without dissolving was verified by swelling kinetics and Moisture Vapour Transmission Rate measurements. Their stability towards mechanical solicitations was assessed by quantifying elasticity, compliance, stress-relaxation, and adhesivity properties. The analyses pointed out that hydrogel PVA-FA2-3 obtained by feruloylation of PVA with bis-imidazole derivative of ferulic acid using an acylation agent/polymer molar ratio 0.03/1 resulted the best candidate for the foreseen application.

Thermomechanical Stress Analysis of Hydrated Vital Gluten with Large Amplitude Oscillatory Shear Rheology

Vital gluten is increasingly researched as a non-food product for biodegradable materials. During processing, the protein network is confronted with increased thermal and mechanical stress, altering the network characteristics. With the prospect of using the protein for materials beyond food, it is important to understand the mechanical properties at various processing temperatures. To achieve this, the study investigates hydrated vital gluten under thermomechanical stress based on large amplitude oscillatory shear (LAOS) rheology. LAOS rheology was conducted at increasing shear strains (0.01-100%), various frequencies (5-20 rad/s) and temperatures of 25, 45, 55, 65, 70 and 85 °C. With elevating temperatures up to 55 °C, the linear viscoelastic moduli decrease, indicating material softening. Then, protein polymerization and the formation of new cross-links due to thermal denaturation cause more network connectivity, resulting in significantly higher elastic moduli. Beyond the linear viscoelastic regime, the strain-stiffening ratio rises disproportionately. This effect becomes even more evident at higher temperatures. Lacking a viscous contribution, the highly elastic but also stiff network shows less mechanical resilience. Additionally, at these elevated temperatures, structural changes during the protein's denaturation and network shrinkage due to water evaporation could be visualized with confocal laser scanning microscopy (CLSM).

Manufacture of Bilayered Composite Hydrogels with Strong, Elastic, and Tough Properties for Osteochondral Repair Applications

Layered composite hydrogels have been considered attractive materials for use in osteochondral repair and regeneration. These hydrogel materials should be mechanically strong, elastic, and tough besides fulfilling some basic requirements such as biocompatibility and biodegradability. A novel type of bilayered composite hydrogel with multi-network structures and well-defined injectability was thus developed for osteochondral tissue engineering using chitosan (CH), hyaluronic acid (HA), silk fibroin (SF), CH nanoparticles (NPs), and amino-functionalized mesoporous bioglass (ABG) NPs. CH was combined with HA and CH NPs to build the chondral phase of the bilayered hydrogel, and CH, SF, and ABG NPs were used together to construct the subchondral phase of the bilayer hydrogel. Rheological measurements showed that the optimally achieved gels assigned to the chondral and subchondral layers had their elastic moduli of around 6.5 and 9.9 kPa, respectively, with elastic modulus/viscous modulus ratios higher than 36, indicating that they behaved like strong gels. Compressive measurements further demonstrated that the bilayered hydrogel with an optimally formulated composition had strong, elastic, and tough characteristics. Cell culture revealed that the bilayered hydrogel had the capacity to support the in-growth of chondrocytes in the chondral phase and osteoblasts in the subchondral phase. Results suggest that the bilayered composite hydrogel can act as an injective biomaterial for osteochondral repair applications.

Current Trends in Gelatin-Based Drug Delivery Systems

Gelatin is a highly versatile natural polymer, which is widely used in healthcare-related sectors due to its advantageous properties, such as biocompatibility, biodegradability, low-cost, and the availability of exposed chemical groups. In the biomedical field, gelatin is used also as a biomaterial for the development of drug delivery systems (DDSs) due to its applicability to several synthesis techniques. In this review, after a brief overview of its chemical and physical properties, the focus is placed on the commonly used techniques for the development of gelatin-based micro- or nano-sized DDSs. We highlight the potential of gelatin as a carrier of many types of bioactive compounds and its ability to tune and control select drugs' release kinetics. The desolvation, nanoprecipitation, coacervation, emulsion, electrospray, and spray drying techniques are described from a methodological and mechanistic point of view, with a careful analysis of the effects of the main variable parameters on the DDSs' properties. Lastly, the outcomes of preclinical and clinical studies involving gelatin-based DDSs are thoroughly discussed.

Gelation Time of Network-Forming Polymer Solutions with Reversible Cross-Link Junctions of Variable Multiplicity

The gelation time tg necessary for a solution of functional (associating) molecules to reach its gel point after a temperature jump, or a sudden concentration change, is theoretically calculated on the basis of the kinetic equation for the stepwise cross-linking reaction as a function of the concentration, temperature, functionality f of the molecules, and multiplicity k of the cross-link junctions. It is shown that quite generally tg can be decomposed into the product of the relaxation time tR and a thermodynamic factor Q. They are functions of a single scaled concentration x≡λ(T)ϕ, where λ(T) is the association constant and ϕ is the concentration. Therefore, the superposition principle holds with λ(T) as a shift factor of the concentration. Additionally, they all depend on the rate constants of the cross-link reaction, and hence it is possible to estimate these microscopic parameters from macroscopic measurements of tg. The thermodynamic factor Q is shown to depend on the quench depth. It generates a singularity of logarithmic divergence as the temperature (concentration) approaches the equilibrium gel point, while the relaxation time tR changes continuously across it. Gelation time tg obeys a power law tg-1∼xn in the high concentration region, whose power index n is related to the multiplicity of the cross-links. The retardation effect on the gelation time due to the reversibility of the cross-linking is explicitly calculated for some specific models of cross-linking to find the rate-controlling steps in order for the minimization of the gelation time to be easier in the gel processing. For a micellar cross-linking covering a wide range of the multiplicity, as seen in hydrophobically-modified water-soluble polymers, tR is shown to obey a formula similar to the Aniansson-Wall law.

Myofibrillar protein can form a thermo-reversible gel through elaborate deamidation using protein-glutaminase

BACKGROUND

Novel thermo-reversible hydrogels that undergo gelation in feedback to external stimuli have numerous applications in the food, biomedical, and functional materials fields. Muscle myofibrillar protein (MP) has long been known for thermally irreversible gelation. Once the reversible gelation of MP is achieved, its scope for research and application will expand.

RESULTS

The work reported here achieved, for the first time, a thermo-reversible MP gelation by elaborate deamidation using protein glutaminase (PG). The protein concentration and PG reaction time within windows of 1.0-2.5% and 8 h or 12 h were observed to be vital for creating thermo-reversible gels. The gel strength increased with protein concentration. The gel displayed a perforated lamellar microstructure, which resulted in a high water-holding capacity. The rheological results revealed the thermo-reversibility of the gel was robust for up to five cycles of heating and cooling. The thermally reversible gelation is closely related to the reversible assembly between individual α-helix and helical coiled coil. Hydrophobic interactions proved to be predominantly involved in the formation and stabilization of the gel network structure.

CONCLUSION

This work increases the scope of research into the thermo-responsive behavior of MP-based gel. It can foster advances in research into the applications of muscle proteins and into the use of PG as a novel ingredient in the food industry. © 2022 Society of Chemical Industry.

Real-time Observation of Macroscopic Helical Morphologies under Optical Microscope: A Curious Case of π-π Stacking Driven Molecular Self-assembly of an Organic Gelator Devoid of Hydrogen Bonding

Supramolecular assemblies such as tubules/helix/double helix/helical tape etc. are usually submicron objects preventing direct observation under optical microscope. Chiral-pure form of these assemblies is important for potential applications. Herein, we report a rare phenomenon wherein a DMSO gel of a simple terpyridine derivative [(4-CNPhe)4PyTerp] produced macroscopic helical morphologies (μm length scale) which could be observed under optical microscope, formation of which could be monitored by optical videography, stable enough to withstand acidic vapour, robust enough to display reversible gel↔sol in response to acidic and ammonia vapour and sturdy enough to be maneuvered with a needle. These properties appeared to be unique to the title compound as the other related derivatives failed to display such assembly structures. SXRD and MD simulation studies suggested that weak interactions (π-π stacking) played a crucial role in the self-assembly process.

Gelation profile of laccase-crosslinked Bambara groundnut (Vigna subterranea) protein isolate

Enzymatic crosslinking has gained attention in improving plant protein heat-induced gels, which are composed of weak network structures. The aim of the study was to investigate the effect of laccase crosslinking on the rheological and microstructural properties of heat-induced Bambara groundnut protein gels. The rheological properties of laccase-modified Bambara groundnut protein isolate (BPI¹) gel formed in situ were investigated. Changes in viscoelastic properties were monitored during heating and cooling ramps and gel structure fingerprints were analyzed by frequency sweep. Laccase addition induced an initial protein structure breakdown (G″>G') at an enzyme dose-dependent (1-3 U/g) before gel formation and stabilization. Gel point temperatures were significantly decreased from 85°C to 29°C (∼3 folds) with increasing laccase activity (0 to 3 U/g protein, respectively). For laccase crosslinked gels, G' was substantially greater than G" (>1 log) with no dependency on angular frequency, which suggests the formation of relatively well-structured gels. The highest gel strength (tan δ of 0.09, G* of 555.51 kPa & An of 468.04 kPa) was recorded at a laccase activity of 2 U/g protein and the gels formed at this activity appeared homogeneous with compact lath sheet-like structure. The crosslinking effects of laccase were corroborated by the decrease in thiol and phenolic contents as well as the crosslinking of amino acids in model reactions. Overall, the use of laccase improved gel properties and significantly altered the gelation profile of BPI. Laccase-modified Bambara groundnut protein gels have potential to be used in food texture improvement and development of new food products. For instance, they can be used in plant-based milk products such as yoghurt and cheese.

Secondary structure and stability of a gel-forming tardigrade desiccation-tolerance protein

Protein-based pharmaceuticals are increasingly important, but their inherent instability necessitates a "cold chain" requiring costly refrigeration during production, shipment, and storage. Drying can overcome this problem, but most proteins need the addition of stabilizers, and some cannot be successfully formulated. Thus, there is a need for new, more effective protective molecules. Cytosolically, abundant heat-soluble proteins from tardigrades are both fundamentally interesting and a promising source of inspiration; these disordered, monodisperse polymers form hydrogels whose structure may protect client proteins during drying. We used attenuated total reflectance Fourier transform infrared spectroscopy, differential scanning calorimetry, and small-amplitude oscillatory shear rheometry to characterize gelation. A 5% (wt/vol) gel has a strength comparable with human skin, and melts cooperatively and reversibly near body temperature with an enthalpy comparable with globular proteins. We suggest that the dilute protein forms α-helical coiled coils and increasing their concentration drives gelation via intermolecular β-sheet formation.

Locust Bean Gum, a Vegetable Hydrocolloid with Industrial and Biopharmaceutical Applications

Locust bean gum (LBG), a vegetable galactomannan extracted from carob tree seeds, is extensively used in the food industry as a thickening agent (E410). Its molecular conformation in aqueous solutions determines its solubility and rheological performance. LBG is an interesting polysaccharide also because of its synergistic behavior with other biopolymers (xanthan gum, carrageenan, etc.). In addition, this hydrocolloid is easily modified by derivatization or crosslinking. These LBG-related products, besides their applications in the food industry, can be used as encapsulation and drug delivery devices, packaging materials, batteries, and catalyst supports, among other biopharmaceutical and industrial uses. As the new derivatized or crosslinked polymers based on LBG are mainly biodegradable and non-toxic, the use of this polysaccharide (by itself or combined with other biopolymers) will contribute to generating greener products, considering the origin of raw materials used, the modification procedures selected and the final destination of the products.

Structural characteristics and rheological properties of hydroxypropyl trimethyl ammonium chloride chitosan

Hydroxypropyl trimethyl ammonium chloride chitosan (HACC) was synthesized by reacting chitosan with glycidyl trimethylammonium chloride. Atomic force microscopy showed that HACC exhibited disorderly coils in dilute solution and formed a three-dimensional network. Flow, thixotropy, and dynamic viscoelasticity tests were conducted using an MCR301 rheometer. The HACC solution was a non-Newtonian pseudoplastic fluid, and the shear behavior of different concentrations (2-6 %, w/v) was evaluated by the Williamson model fitting. Furthermore, the thixotropy was highly dependent on concentration changes: the high-concentration solution structure was difficult to recover in a short time. The dynamic viscoelasticity test indicated that the viscoelasticity of the HACC solution not only exhibited a viscous behavior similar to that of a fluid, but also exhibited elastic properties of weak gel. HACC exhibited high-strength solid-like gel characteristics at high temperature.

Strong and Elastic Hydrogels from Dual-Crosslinked Composites Composed of Glycol Chitosan and Amino-Functionalized Bioactive Glass Nanoparticles

Mesoporous bioactive glass (BG) nanoparticles (NPs) with a high specific surface area were prepared. The surfaces of BG NPs were further modified using an amino-containing compound or synthesized precursors to produce three kinds of amino-functionalized bioactive glass (ABG) NPs via devised synthetic routes. The achieved ABG NPs possessed various spacer lengths with free amino groups anchored at the end of the spacer. These ABG NPs were then combined with glycol chitosan (GCH) to construct single- or dual-crosslinked ABG/GCH composite hydrogels using genipin (GN) alone as a single crosslinker or a combination of GN and poly(ethylene glycol) diglycidyl ether (PEGDE) as dual crosslinkers. The spacer length of ABG NPs was found to impose significant effects on the strength and elasticity of GN-crosslinked ABG/GCH hydrogels. After being dually crosslinked with GN and PEGDE, the elastic modulus of some dual-crosslinked ABG/GCH hydrogels reached around 6.9 kPa or higher with their yielding strains larger than 60%, indicative of their strong and elastic features. The optimally achieved ABG/GCH hydrogels were injectable with tunable gelation time, and also able to support the growth of seeded MC3T3-E1 cells and specific matrix deposition. These results suggest that the dual-crosslinked ABG/GCH hydrogels have the potential for some applications in tissue engineering.

Strong and Elastic Chitosan/Silk Fibroin Hydrogels Incorporated with Growth-Factor-Loaded Microspheres for Cartilage Tissue Engineering

An emulsification method was developed for fabricating core-shell microspheres with a thick shell layer. Kartogenin (KGN) and platelet-derived growth factor BB (PDGF-BB) were respectively loaded into the core portion and the shell layer of the microspheres with high loading efficiency. The optimally built microspheres were combined with chitosan (CH) and silk fibroin (SF) to construct a new type of composite hydrogel with enhanced strength and elasticity, using genipin or/and tyrosinase as crosslinkers for the intended use in cartilage tissue engineering. The composite hydrogels were found to be thermo-responsive at physiological temperature and pH with well-defined injectability. Rheological measurements revealed that they had an elastic modulus higher than 6 kPa with a high ratio of elastic modulus to viscous modulus, indicative of their mechanically strong features. Compressive measurements demonstrated that they possessed well-defined elasticity. In addition, some gels had the ability to administer the temporal separation release of PDGF-BB and KGN in an approximately linear manner for several weeks. The released PDGF-BB was found to be bioactive based on its effects on Balb/c 3T3 cells. The composite gels supported the growth of seeded chondrocytes while preserving their phenotype. The results suggest that these composite gels have the potential for endogenous cartilage repair.

Effect of hydrocolloids on physicochemical properties, stability, and digestibility of Pickering emulsions stabilized by nanofibrillated cellulose

In this study, the effect of hydrocolloids with different electrostatic characteristics, namely negatively charged xanthan gum (XG), positively charged chitosan (CH), and non-ionic guar gum (GG), on the physicochemical properties, stability, and lipid digestibility of 10% (w/w) soybean oil-in-water Pickering emulsions stabilized by nanofibrillated cellulose (NFC) was investigated. Addition of XG and CH to the NFC-stabilized emulsions significantly increased the oil droplet sizes and apparent viscosity at high shear rates as compared with the addition of GG. The XG added emulsion showed the lowest rate and extent of creaming, whereas the CH added emulsion gave the highest extent of creaming. The addition of XG and CH led to a more pronounced effect on in vitro lipid digestion, i.e. changes in droplet sizes, surface charges, microstructure, and free fatty acid (FFA) release, than the addition of GG. The XG added emulsion showed the lowest rate and extent of lipid digestion possibly due to the high viscosity of the aqueous phase, large oil droplet sizes, and interaction of XG and calcium, resulting in the reduction of lipase activity. The CH added emulsion exhibited the highest extent of lipid digestion possibly due to binding between CH and FFAs and move away from the droplet surfaces, thereby facilitating the lipase activity. In summary, it can be concluded that ionic hydrocolloids exerted more influence on NFC-stabilized Pickering emulsions than non-ionic ones. These results may facilitate the design of highly stable emulsion-based functional food products with added hydrocolloids to promote health and wellness.

Characterization and Biocompatibility Properties In Vitro of Gel Beads Based on the Pectin and κ-Carrageenan

This study aimed to investigate the influence of kappa (κ)-carrageenan on the initial stages of the foreign body response against pectin gel. Pectin-carrageenan (P-Car) gel beads were prepared from the apple pectin and κ-carrageenan using gelling with calcium ions. The inclusion of 0.5% κ-carrageenan (Car0.5) in the 1.5 (P1.5) and 2% pectin (P2) gel formulations decreased the gel strength by 2.5 times. Car0.5 was found to increase the swelling of P2 gel beads in the cell culture medium. P2 gel beads adsorbed 30–42 mg/g of bovine serum albumin (BSA) depending on pH. P2-Car0.2, P2-Car0.5, and P1.5-Car0.5 beads reduced BSA adsorption by 3.1, 5.2, and 4.0 times compared to P2 beads, respectively, at pH 7. The P1.5-Car0.5 beads activated complement and induced the haemolysis less than gel beads of pure pectin. Moreover, P1.5-Car0.5 gel beads allowed less adhesion of mouse peritoneal macrophages, TNF-α production, and NF-κB activation than the pure pectin gel beads. There were no differences in TLR4 and ICAM-1 levels in macrophages treated with P and P-Car gel beads. P2-Car0.5 hydrogel demonstrated lower adhesion to serous membrane than P2 hydrogel. Thus, the data obtained indicate that the inclusion of κ-carrageenan in the apple pectin gel improves its biocompatibility.

Effect of pH and Pea Protein: Xanthan Gum Ratio on Emulsions with High Oil Content and High Internal Phase Emulsion Formation

Electrostatic interaction between protein and polysaccharides could influence structured liquid oil stability when emulsification is used for this purpose. The objective of this work was to structure sunflower oil forming emulsions and High Internal Phase Emulsions (HIPEs) using pea protein (PP) and xanthan gum (XG) as a stabilizer, promoting or not their electrostatic attraction. The 60/40 oil-in-water emulsions were made varying the pH (3, 5, and 7) and PP:XG ratio (4:1, 8:1, and 12:1). To form HIPEs, samples were oven-dried and homogenized. The higher the pH, the smaller the droplet size (Emulsions: 15.60-43.96 µm and HIPEs: 8.74-20.38 µm) and the oil release after 9 weeks of storage at 5 °C and 25 °C (oil loss < 8%). All systems had weak gel-like behavior, however, the values of viscoelastic properties (G' and G″) increased with the increment of PP:XG ratio. Stable emulsions were obtained at pHs 5 and 7 in all PP:XG ratios, and at pH 3 in the ratio 4:1. Stable HIPEs were obtained at pH 7 in the ratios PP:XG 4:1, 8:1, and 12:1, and at pH 5 at PP:XG ratio 4:1. All these systems presented different characteristics that could be exploited for their application as fat substitutes.

Natural Polymeric Scaffolds for Tissue Engineering Applications

Natural polymeric scaffolds can be used for tissue engineering applications such as cell delivery and cell-free supporting of native tissues. This is because of their desirable properties such as; high biocompatibility, tunable mechanical strength and conductivity, large surface area, porous- and extracellular matrix (ECM)-mimicked structures. Specifically, their less toxicity and biocompatibility makes them suitable for several tissue engineering applications. For these reasons, several biopolymeric scaffolds are currently being explored for numerous tissue engineering applications. To date, research on the nature, chemistry, and properties of nanocomposite biopolymers are been reported, while the need for a comprehensive research note on more tissue engineering application of these biopolymers remains. As a result, this present study comprehensively reviews the development of common natural biopolymers as scaffolds for tissue engineering applications such as cartilage tissue engineering, cornea repairs, osteochondral defect repairs, and nerve regeneration. More so, the implications of research findings for further studies are presented, while the impact of research advances on future research and other specific recommendations are added as well.

Rheological Analysis of the Structuralisation Kinetics of Starch Gels

Using the method of dynamic–mechanical analysis, the structuralisation kinetics of condensed starch solutions, cooled down to the temperature of 20 °C, was investigated. A close correlation of spatial crosslinking with local processes of macromolecule associations was discovered. It was found that depending on the concentration intervals of starch solutions, equilibrium nodes of the spatial network assume the form of either single or double hexagonal structures made up of bispiral chain associates. The increase of gel crosslinking, together with the passage of time, is the result of increasing the node functionality of the spatial network.

Physical Aspects of Organogelation: A Point of View

The physics side of organogelation is broached through three main aspects, thermodynamics (formation and melting), structure (morphology and molecular organization), and rheology. A definition of a gel is first discussed so as to delimit the field of investigation; namely, systems constituted of fibril-like entities. It is again highlighted that gel formation occurs through first-order transitions, chiefly by homogeneous nucleation. A deeper knowledge of the system is thus achieved by mapping out the temperature–concentration phase diagram. Some experimental diagrams are shown, while diagrams likely to pertain to these systems are presented. The molecular arrangement is basically crystallization that occurs in a preferred direction, hence the formation of fibrils. The effects of the solvent type, the quenching process of the solution are discussed with respect to the morphology and the crystal structure. Finally, the rheological properties are tackled. Notions of critical gelation concentration and percolation are debated. The interest of mapping out the temperature–concentration phase diagram is emphasized, particularly for understanding the variation of the gel modulus with temperature.

Thermo-responsive chitosan/silk fibroin/amino-functionalized mesoporous silica hydrogels with strong and elastic characteristics for bone tissue engineering

Amino-functionalized mesoporous silica nanoparticles with radially porous architecture were optimally synthesized, and they were used together with silk fibroin and chitosan to produce a type of covalently crosslinked composite hydrogel using genipin as a crosslinker. The optimally achieved composite gels were found to be thermo-responsive at physiological temperature and pH with well-defined injectability. They were also detected to have mechanically strong and elastic characteristics. In addition, these gels showed the ability to release bioactive Si ions suited to an effective dose range in approximately linear manners for a few weeks. Studies on the cell-gel constructs revealed that the composite gels well supported the growth of seeded MC3T3-E1 cells, and the deposition of matrix components. Results obtained from the detection of alkaline phosphatase activity and the matrix mineralization in the cell-gel constructs confirmed that these composite gels had certain osteogenic capacity. The obtained results suggest that these composite gels have promising potential in bone repair and regeneration.

Effects of damaged starch on glutinous rice flour properties and sweet dumpling qualities

This study focused on exploring the effects of damaged starch on glutinous rice flour properties and sweet dumpling qualities. Glutinous rice flours with different damaged starch contents (2-8%) and the same particle size were prepared through sifting and blending of semidry-milled and dry-milled rice flour. The increase of damaged starch content led to an increase in elastic modulus (G'), viscous modulus (G″) and agglomeration of starch granules, and a decrease in peak viscosity, breakdown value and enthalpy change (ΔH). Among all the samples, the rice flour batters with damaged starch content 3% and 4% were more stable and structured, and rice flours with damaged starch content 2% and 3% showed better pasting properties. As for the sweet dumpling qualities, compact structure, weak water mobility, less water loss, slight cracking and desirable cooking and texture properties were observed in the sweet dumplings made from rice flour with damaged starch content of less than 5%. All the results demonstrated that glutinous rice flour with damaged starch content of less than 5% had good flour properties and was suitable for the production of sweet dumplings.

Precise control of synthetic hydrogel network structure via linear, independent synthesis-swelling relationships

Hydrogel physical properties are tuned by altering synthesis conditions such as initial polymer concentration and polymer-cross-linker stoichiometric ratios. Traditionally, differences in hydrogel synthesis schemes, such as end-linked poly(ethylene glycol) diacrylate hydrogels and cross-linked poly(vinyl alcohol) hydrogels, limit structural comparison between hydrogels. In this study, we use generalized synthesis variables for hydrogels that emphasize how changes in formulation affect the resulting network structure. We identify two independent linear correlations between these synthesis variables and swelling behavior. Analysis through recently updated swollen polymer network models suggests that synthesis-swelling correlations can be used to make a priori predictions of the stiffness and solute diffusivity characteristics of synthetic hydrogels. The same experiments and analyses performed on methacrylamide-modified gelatin hydrogels demonstrate that complex biopolymer structures disrupt the linear synthesis-swelling correlations. These studies provide insight into the control of hydrogel physical properties through structural design and can be used to implement and optimize biomedically relevant hydrogels.

A review on structural, digestibility and physicochemical properties of legume starch-lipid complexes

There is a growing interest in alternative sources of starch for various industrial applications to cater for the increasing demand of starch, avoid the sole reliance on conventional sources such as corn and to prevent shortage of supply. Legume starches with high levels of amylose and high resistant starch contents are suitable alternatives. However, starch must be modified to overcome the shortcomings associated with native starches. The modification of starch with lipids results in the formation of inclusion complexes, called V-amylose complexes with improved physicochemical and functional properties and this category of modified starch is further regarded as clean-label. Clean-label ingredients are consumer and environmentally friendly and do not contain synthetic chemicals that may present food safety concerns. This review documents the current level of research on V-amylose complexes formed using legumes starches and outlines research gaps that could be explored for better utilisation of these legumes in the industry.

Role of Normal Stress in the Creep Dynamics and Failure of a Biopolymer Gel

We investigate the delayed rupture of biopolymer gels under a constant shear load by simultaneous dynamic light scattering and rheology measurements. We unveil the crucial role of normal stresses built up during gelation: All samples that eventually fracture self-weaken during the gelation process, as revealed by a partial relaxation of the normal stress concomitant to a burst of microscopic plastic rearrangements. Upon applying a shear stress, weakened gels exhibit in the creep regime distinctive signatures in their microscopic dynamics, which anticipate macroscopic fracture by up to thousands of seconds. The dynamics in fracturing gels are faster than those of nonfracturing gels and exhibit large spatiotemporal fluctuations. A spatially localized region with significant plasticity eventually nucleates, expands progressively, and finally invades the whole sample, triggering macroscopic failure.

Effect of Curdlan on the Rheological Properties of Hydroxypropyl Methylcellulose

This work focuses on the effect of curdlan (CL) on dynamic viscoelastic property, thermal reversible property, viscosity, and the fluid types of hydroxypropyl methylcellulose (HPMC) at different temperatures. Compared to the blends at 25 °C, the blends had a smaller linear viscoelastic region (LVR), a higher gel strength, and larger storage modulus (G') and loss modulus (G") values at 82 °C. G', G", gel strength, and viscosity increased with the increase of CL. Repeated temperature sweep led to increased G' and G" of HPMC/CL blends. For HC6 and HC8, the gel formation temperature of the repeated temperature sweep was significantly lower than that of the first sweep. The samples at 82 °C, except for the sample with 8% CL, were all yield-shear thinning fluids, and the samples at 40 °C were shear thinning fluids. The creation of HPMC/CL and its rheological research might provide some methodological references for the study of other thermal-thermal gel blends.

Validating the textural characteristics of soft fish-based paste through International Dysphagia Diet Standardisation Initiative recommended tests

One in every twelve people worldwide suffers from dysphagia that affects the swallowing mechanism and some patients require a special texture-modified food for their sustenance. Fish is a great source of nutrients and proteins, however the commercially dysphagia diet made from fish is limited. This study investigated the textural characteristics of a soft fish paste produced from steamed grass carp fillet with different the water addition, grinding cycles and ratio of starch with the mixture of steamed fillet and water, following International Dysphagia Diet Standardisation Initiative (IDDSI) guidelines and other instruments. The water addition and particle size affected the physical properties, and the starch had a certain masking effect on fishy odor. The mixture of steamed fish fillets and water (91:9 wt/wt) was ground in a colloid mill for 3 cycles. The fish paste was then sterilized by adding sugar, salt, and starch in the mixture (ratios of 0.5:100, 0.5:100, and 0.6:100, wt/wt, respectively) and mixing well. The paste conformed to Level 4-pureed and extremely thick of IDDSI framework. The fish paste product had a light fishy odor that was acceptable to sensory specialists.