Preparation of model starch complex hydrogels

G-POSS connected double network starch gels for protein release

Starch is one of the most frequently preferred natural polymers in hydrogel synthesis. Herein, we combined two strategies of associating brittle and ductile networks in a structure and incorporating inorganic particles into the polymeric gel to design mechanically enhanced nanocomposite double network (DN) starch gels. For the first time in the literature, nanocomposite starch gels (s-NC) were designed by cross-linking starch chains with 8-armed glycidyl-polyhedral oligomeric silsesquioxane (g-POSS) units. Fourier Transform Infrared Spectroscopy and Energy Dispersive X-Ray Spectroscopy analyses have proven that g-POSS is included in the gel structure and is homogeneously distributed throughout the network. More stable d-NC-DMA and d-NC-VP gels were obtained by incorporating N,N-dimethylacrylamide (DMA), or 1-vinyl-2-pyrrolidinone (VP) units, respectively, into g-POSS-linked starch gels, and the reaction kinetics were followed in situ. In SEM images, it was observed that d-NC-DMA had smaller pores and thicker pore walls compared to s-NC and d-NC-VP starch gels, and its mechanical strength was shown to be much superior by rheological tests, compression, and tensile analyses. In addition to increasing the mechanical strength of the gels, the potential of starch in protein release applications using amylase sensitivity has been demonstrated in vitro experiments using the model protein BSA.

Bioactive delivery systems based on starch and its derivatives: Assembly and application at different structural levels

Starch and modified starch, spanning various structural levels, are comprehensively reviewed, with a special emphasis on the advancement of starch and its derivative-based delivery systems for bioactive substances. The pivotal aspect highlighted is the controlled release of active ingredients by starch-based delivery systems with distinct hierarchical structures. At the molecular level, diverse categories of starch degradation products, such as dextrin and highly branched starch, serve as versatile amphiphilic carriers for encapsulating active ingredients. At the level of helical structure, the distinctive configuration of the starch-guest complex partly determines the mechanism of controlled release for diverse active components. At the crystal and particle structural level, starch assumes the role of a carrier, effectively modulating the release of active substances, and enhances the innate physiological activity of different active components. As a natural polymer molecule, starch can also generate hydrogel materials in polymer form, expanding its utility in the fields of food, materials, and even medicine.

In situ forming of PEG-NH2/dialdehyde starch Schiff-base hydrogels and their application in slow-release urea

In this study, a biodegradable Schiff-base hydrogel urea, possessing substantial water retention and certain slow-release ability was designed and synthesized. Firstly, dialdehyde starch (DAS) and amine-terminated polyethylene glycol (PEG-(NH2)2) were synthesized using potato starch and polyethylene glycol. Then, a novel Schiff-base hydrogel (SH) was prepared through the in-situ reaction between the aldehyde group of DAS and the amino group of PEG-(NH2)2. Three SH based slow-release urea, designated as SHU1, SHU2, and SHU3 and distinguished by varying urea content, were obtained using SH as the substrate. Several characterizations and tests were conducted to determine the structure, thermal properties, morphology, swelling properties, sustainable use, water retention, and biodegradation properties of SH. Additionally, the slow-release behavior of SHU was studied. SEM results revealed that SH possessed a porous three-dimensional network structure, with a maximum water absorption capacity of 4440 % ± 6.23 %. Compared to pure urea, SHU exhibited better slow-release performance after 30 days of release in soil, with SHU1 having a residual nitrogen content of specifically 36.01 ± 0.57 % of the initial nitrogen content. A pot experiment with pakchoi substantiated the water retention and plant growth promotion properties of SHU. This study demonstrated a straightforward method for the preparation of starch-based Schiff-base hydrogels as fertilizer carriers.

Green Synthesis of Low-Glycemic Amylose-Lipid Nanocomposites by High-Speed Homogenization and Formulation into Hydrogel

In this research, we focused on the production of amylose-lipid nanocomposite material (ALN) through a green synthesis technique utilizing high-speed homogenization. Our aim was to investigate this novel material's distinctive physicochemical features and its potential applications as a low-glycemic gelling and functional food ingredient. The study begins with the formulation of the amylose-lipid nanomaterial from starch and fatty acid complexes, including stearic, palmitic, and lauric acids. Structural analysis reveals the presence of ester carbonyl functionalities, solid matrix structures, partial crystallinities, and remarkable thermal stability within the ALN. Notably, the ALN exhibits a significantly low glycemic index (GI, 40%) and elevated resistance starch (RS) values. The research extends to the formulation of ALN into nanocomposite hydrogels, enabling the evaluation of its anthocyanin absorption capacity. This analysis provides valuable insights into the rheological properties and viscoelastic behavior of the resulting hydrogels. Furthermore, the study investigates anthocyanin encapsulation and retention by ALN-based hydrogels, with a particular focus on the influence of pH and physical cross-link networks on the uptake capacity presenting stearic-acid (SA) hydrogel with the best absorption capacity. In conclusion, the green-synthesized (ALN) shows remarkable functional and structural properties. The produced ALN-based hydrogels are promising materials for a variety of applications, such as medicine administration, food packaging, and other industrial purposes.

Research Progress of Polysaccharide-Based Natural Polymer Hydrogels in Water Purification

The pollution and scarcity of freshwater resources are global problems that have a significant influence on human life. It is very important to remove harmful substances in the water to realize the recycling of water resources. Hydrogels have recently attracted attention due to their special three-dimensional network structure, large surface area, and pores, which show great potential for the removal of pollutants in water. In their preparation, natural polymers are one of the preferred materials because of their wide availability, low cost, and easy thermal degradation. However, when it is directly used for adsorption, its performance is unsatisfactory, so it usually needs to be modified in the preparation process. This paper reviews the modification and adsorption properties of polysaccharide-based natural polymer hydrogels, such as cellulose, chitosan, starch, and sodium alginate, and discusses the effects of their types and structures on performance and recent technological advances.

Green starch/graphene oxide hydrogel nanocomposites for sustained release applications

Green nanocomposite hydrogels (ST-PHEMA/GO) comprised of starch and 2-Hydroxyethyl methacrylate (HEMA) reinforced with different ratios of graphene oxide (GO) were prepared via gamma radiation induced crosslinking polymerization. The chemical structure and morphology and the crystallinity were studied by FTIR FE-SEM, AFM, TEM and XRD, respectively. The swelling behavior of the claimed hydrogels was verified versus time and the pH-dependent swelling at three different irradiation dose:10, 20 and 30 kGy was also investigated. The results of the swelling study showed that the swelling capacity of the hydrogel networks varied with the changes of the pH of the solution, the GO content and the irradiation doses. Moreover, the swelling isotherm of all the prepared hydrogels followed a Fickian diffusion mechanism n < 0.5.

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Dual Cross-Linked Starch–Borax Double Network Hydrogels with Tough and Self-Healing Properties

Herein, we have fabricated starch–borax double cross-linked network (DC) hydrogels with tough and self-healing properties using a one-pot method. The addition of borax significantly increased the storage modulus and loss modulus of these starch–borax DC hydrogels. The maximum compression stress (~288 kPa) of starch–borax DC hydrogels containing 5% borax was about ten times greater than that of a pure-starch hydrogel. The texture profile analysis values of the DC hydrogels—including hardness, springiness, cohesiveness, and adhesiveness—increased compared to pure-starch hydrogels. In addition, starch–borax DC hydrogels exhibited excellent self-healing and shape-recovery properties. These DC hydrogels, with a variety of excellent properties, have potential applications in agricultural, biomedical, and industrial fields.

Recent advances in the structure, synthesis, and applications of natural polymeric hydrogels

Hydrogels, polymeric network materials, are capable of swelling and holding the bulk of water in their three-dimensional structures upon swelling. In recent years, hydrogels have witnessed increased attention in food and biomedical applications. In this paper, the available literature related to the design concepts, types, functionalities, and applications of hydrogels with special emphasis on food applications was reviewed. Hydrogels from natural polymers are preferred over synthetic hydrogels. They are predominantly used in diverse food applications for example in encapsulation, drug delivery, packaging, and more recently for the fabrication of structured foods. Natural polymeric hydrogels offer immense benefits due to their extraordinary biocompatible nature. Hydrogels based on natural/edible polymers, for example, those from polysaccharides and proteins, can serve as prospective alternatives to synthetic polymer-based hydrogels. The utilization of hydrogels has so far been limited, despite their prospects to address various issues in the food industries. More research is needed to develop biomimetic hydrogels, which can imitate the biological characteristics in addition to the physicochemical properties of natural materials for different food applications.

Assembly of propylene glycol alginate/β-lactoglobulin composite hydrogels induced by ethanol for co-delivery of probiotics and curcumin

Probiotics and curcumin can exhibit synergistic biological activities on the basis of a gut-brain axis, but are sensitive to environmental conditions, making it a challenge for their co-utilization. To meet the demand for high efficiency and convenience, both probiotics and curcumin were encapsulated within a propylene glycol alginate-based hydrogel delivery system, which was assembled using an ethanol-induced approach. The composite hydrogel was effective at sustaining the release of curcumin and protecting LGG cells in simulated gastrointestinal tract conditions. Moreover, it could also largely reduce the chemical degradation of curcumin and increase the survival of LGG during light exposure and long-term storage: up to 91.3 % of curcumin and 9.72 log CFU cm^-3 remained present throughout 4 weeks of storage. Results in this work demonstrate a low-energy and green approach to assemble a composite hydrogel with remarkable biocompatibility, which is considered as a desired delivery vehicle for co-delivery of probiotics and curcumin.