Development of Self-Healing Double-Network Hydrogels: Enhancement of the Strength of Wheat Gluten Hydrogels by In Situ Metal-Catechol Coordination

Effect of ethanol addition on the physicochemical, structural and in vitro digestive properties of Tartary buckwheat starch-quercetin/rutin complexes

The effects of ethanol on the physicochemical, structural and in vitro digestive properties of Tartary buckwheat starch-quercetin/rutin complexes (e-TBSQ and e-TBSR) were investigated. Ethanol restricted the gelatinization of Tartary buckwheat starch (TBS), which resulted an increase in ∆H, G' and G" as well as a decrease in apparent viscosity of e-TBSQ and e-TBSR. The particle size, scanning electron microscopy and X-ray diffraction results showed that ethanol influenced the morphological structure of TBS granules and the starch crystalline structure in e-TBSQ and e-TBSR changed from B-type to V-type when the ethanol concentration was 25%. Saturation transfer difference-nuclear magnetic resonance results revealed that ethanol weakened the binding ability of quercetin/rutin to TBS in e-TBSQ and e-TBSR, leading to a change in the binding site on the quercetin structural unit. The residual ungelatinized TBS granules in e-TBSQ and e-TBSR induced a high slowly digestible starch content, and thus displayed a "resistant-to-digestion".

Inherent molecular characteristics and effect of garlic polysaccharides on dough micro- and mesoscopic properties

Directional control of the process of doughs with nutrition fortification is challenging. Thus, this study aimed to develop non-starch polysaccharides that can modify the quality of flour products. Polysaccharides were extracted from three different garlic cultivars, evaluated for physicochemical properties and used to enrich doughs for microstructure and mesoscopic characteristics analysis. We assessed the moisture distribution, texture characteristics, thermodynamic properties, dynamic viscoelastic properties, protein structure, microstructure and molecular interaction of the doughs and demonstrated a relatively high molecular weight, lower steric hindrance of molecular chains and higher cross-linking ability with the dough network in the supernatant polysaccharide from Yunnan single-clove-garlic (SGSOS) fraction. These features of SGSOS fraction improved the rheological, thermodynamic, texture characteristics, and water distribution of doughs. These findings provide information on the use of garlic polysaccharides during the processing and manufacturing of foods to enhance their processing adaptability and qualities.

Preparation and Characterization of Gluten/SDS/Chitosan Composite Hydrogel Based on Hydrophobic and Electrostatic Interactions

Gluten is a natural byproduct derived from wheat starch, possessing ideal biocompatibility. However, its poor mechanical properties and heterogeneous structure are not suitable for cell adhesion in biomedical applications. To resolve the issues, we prepare novel gluten (G)/sodium lauryl sulfate (SDS)/chitosan (CS) composite hydrogels by electrostatic and hydrophobic interactions. Specifically, gluten is modified by SDS to give it a negatively charged surface, and then it conjugates with positively charged chitosan to form the hydrogel. In addition, the composite formative process, surface morphology, secondary network structure, rheological property, thermal stability, and cytotoxicity are investigated. Moreover, this work demonstrates that the change can occur in surface hydrophobicity caused by the pH-eading influence of hydrogen bonds and polypeptide chains. Meanwhile, the reversible non-covalent bonding in the networks is beneficial to improving the stability of the hydrogels, which shows a prominent prospect in biomedical engineering.

Multi-crosslinked network chitosan films containing caffeic acid and Fe3+ with high anti-oxidation and anti-UV abilities

In this study, caffeic acid (CA) and Fe³⁺ were added to chitosan solution to prepare chitosan/caffeic acid/Fe³⁺ (CCAF) composite films. CA was used to introduce covalent bonds and hydrogen bonds. Fe³⁺ was used to introduce metal coordination bonds which combined with hydrogen bond and covalent bonds to form a multi-crosslinked system to enhance the tensile strength (TS), improve the antioxidant properties and UV resistance performance. The results showed that the TS of chitosan/caffeic acid (CCA) film with the addition of 0.3 mmol CA was increased by 36.6 % compared with pure chitosan film. The TS of the CCAF film increased from 42.6 MPa to 73.9 MPa with an increase of 73.5 %. The free radical scavenging rate of CCA film and CCAF film, in comparison to pure chitosan film, were improved by 155.7 % and 148.24 %, respectively. The UV resistance property of the CCAF solution was tested at 365 nm and the results showed that the UV barrier rate reached 99.99 %. The water vapor transmission (WVT) and water vapor permeability (WVP) of CCAF film both showed a 25.71 % reduction compared to that of the chitosan film. Besides, the composite film also showed excellent antibacterial properties, which provided the possibility for more applications.

Synthesis and Rheological Characterization of a Novel Salecan Hydrogel

Salecan (Sal) is a novel microbial polysaccharide. In the present research, thermal treatment was performed to fabricate Sal hydrogel. The effect of Sal concentration on water holding capacity, swelling properties, texture properties, and microstructure of the hydrogels was discussed. It was found that the equilibrium degree of swelling (EDS) of Sal hydrogels was above 1500%, inferred Sal was a highly hydrophilic polysaccharide. As Sal concentration increased from 3.5 to 8.0 wt%, the hardness increased from 0.88 to 2.07 N and the water hold capability (WHC) increased from 91.3% to 98.2%. Furthermore, the internal network structure of Sal hydrogel also became denser and more uniform. Rheological studies suggested that elastic hydrogel formed under the gelation process. All these results demonstrated that Sal hydrogel prepared by thermal treatment had good gelling properties, which opened up a new safe way for the preparation of Sal hydrogel and broadened the application range of Sal.

Double noncovalent network chitosan/hyperbranched polyethylenimine/Fe3+ films with high toughness and good antibacterial activity

The application of pure chitosan films is significantly limited due to their poor mechanical properties. In this study, a novel type of chitosan/hyperbranched polyethylenimine (CHP) and chitosan/hyperbranched polyethylenimine/Fe³⁺ (CHPF) films with high toughness and good antibacterial activity were prepared through a noncovalent crosslinking method. From the tensile test results, the strain and toughness of the CHP film increased by 798.1% and 292.3%, respectively, compared with pure chitosan film, after the addition of 20% hyperbranched polyethylenimine (HPEI). The addition of trace metal iron ions (3 mg) forms a metal coordination bond with the amine group on HPEI, as well as the hydroxyl group and amine group on chitosan, and develops a double noncovalent bond network structure with hydrogen bonding, which further enhances the mechanical tensile strength of the chitosan-based film, with an increase of 48.4%. Interestingly, HPEI and Fe³⁺ can be used as switches to increase and decrease the fluorescence property of chitosan, respectively. Furthermore, the CHP and CHPF films showed good antibacterial activity against S. aureus and E. coli.

Double noncovalent network chitosan/hyperbranched polyethylenimine/Fe³⁺ films.

Di(2-picolyl)amine-functionalized poly(ethylene glycol) hydrogels with tailorable metal–ligand coordination crosslinking

A new class of metallo-hydrogels has been developed using di(2-picolyl)amine (DPA)-functionalized 4-arm polyethylene glycol (4A-PEG-DPAn) polymers crosslinked by metal–ligand coordination.

Physical and Chemical Factors Influencing the Printability of Hydrogel-based Extrusion Bioinks

Bioprinting researchers agree that "printability" is a key characteristic for bioink development, but neither the meaning of the term nor the best way to experimentally measure it has been established. Furthermore, little is known with respect to the underlying mechanisms which determine a bioink's printability. A thorough understanding of these mechanisms is key to the intentional design of new bioinks. For the purposes of this review, the domain of printability is defined as the bioink requirements which are unique to bioprinting and occur during the printing process. Within this domain, the different aspects of printability and the factors which influence them are reviewed. The extrudability, filament classification, shape fidelity, and printing accuracy of bioinks are examined in detail with respect to their rheological properties, chemical structure, and printing parameters. These relationships are discussed and areas where further research is needed, are identified. This review serves to aid the bioink development process, which will continue to play a major role in the successes and failures of bioprinting, tissue engineering, and regenerative medicine going forward.

Effects of edible plant polyphenols on gluten protein functionality and potential applications of polyphenol-gluten interactions

Expanding plant-based protein applications is increasingly popular. Polyphenol interactions with wheat gluten proteins can be exploited to create novel functional foods and food ingredients. Polyphenols are antioxidants, thus generally decrease gluten strength by reducing disulfide cross-linking. Monomeric polyphenols can be used to reduce dough mix time and improve flexibility of the gluten network, including to plasticize gluten films. However, high-molecular-weight polyphenols (tannins) cross-link gluten proteins, thereby increasing protein network density and strength. Tannin-gluten interactions can greatly increase gluten tensile strength in dough matrices, as well as batter viscosity and stability. This could be leveraged to reduce detrimental effects of healthful inclusions, like bran and fiber, to loaf breads and other wheat-based products. Further, the dual functions of tannins as an antioxidant and gluten cross-linker could help restructure gluten proteins and improve the texture of plant-based meat alternatives. Tannin-gluten interactions may also be used to reduce inflammatory effects of gluten experienced by those with gluten allergies and celiac disease. Other potential applications of tannin-gluten interactions include formation of food matrices to reduce starch digestibility; creation of novel biomaterials for edible films or medical second skin type bandages; or targeted distribution of micronutrients in the digestive tract. This review focuses on the effects of polyphenols on wheat gluten functionality and discusses emerging opportunities to employ polyphenol-gluten interactions.

Unsaturation and Polar Head Effect on Gelation, Bioactive Release, and Cr/Cu Removal Ability of Glycolipids

Designing of multifunctional soft and smart materials from natural sources is a useful strategy for producing safer chemicals having potential applications in biomedical research and pharmaceutical industries. Herein, eight glycolipids with variation in unsaturation of hydrophobic tail and polar headgroup size were designed. The effect of unsaturation in the tail group and headgroup size on gelation ability, and mechanical and thermal stability of glycolipid hydro/organogels was studied to understand structure and property relationship. Glycolipids are functional amphiphilic molecules having potential applications in the field of drug delivery and metal removal. The encapsulation capacity and kinetic release behavior of hydrophobic/hydrophilic bioactives like curcumin/riboflavin from the hydrophobic/hydrophilic pockets of glycolipids hydro/organogels was examined. A significant observation was that the glucamine moiety of the glycolipid headgroup plays a vital role in removal of Cr and Cu from oil/water biphasic systems. Typical functions of the glycolipid hydrogels are metal chelation and enzyme-triggered release behavior, enabled them as promising material for Cr, Cu removal from edible oils and controlled release of water soluble/insoluble bioactives.