Starch Hydrogels Research Articles

Quantifying the water donation potential of commercial and corn starch hydrogels in a cementitious matrix

In this study, we introduce a new methodology to quantify the internal curing potential of hydrogels in a cementitious matrix. The swollen Super Absorbent Polymers (SAPs) and newly synthesized corn-starch hydrogels are investigated by embedding a capsule filled with swollen hydrogel in a cement mortar cube and monitoring the internal wetting area around the hydrogel capsule for 56 days. Our findings demonstrate that all of the investigated hydrogels serve as effective internal curing agents, releasing water in a cyclic pattern governed by the humidity gradient between the hydrogel and the surrounding matrix. Moreover, the regions around the hydrogel capsules display a denser accumulation of calcium silicate hydrate (CSH) gel, indicating improved hydration due to internal curing from the hydrogels. This research offers valuable understanding into the possibilities of utilizing bio-based materials and SAPs for internal curing and the creation of environmentally friendly cementitious materials. In summary, the proposed innovative approach serves as an effective way for measuring the internal curing capabilities of hydrogels within cementitious materials.

Effect of starch type and chitosan supplementation on physicochemical properties, morphology, and oil structuring capacity of composite starch bioaerogels

Oleogelation is a novel fat structuring method for converting liquid oils to solidified oil to reduce trans-fatty acids and saturated fat content in food formulations. In the current study, the impact of starch type and chitosan addition on the oleogelation capacity of aerogels obtained from supercritical CO2 drying technology was investigated. The starch hydrogel precursors were prepared from dent starch (27% amylose content), 55% amylose, and 72% amylose starch in the presence of 0, 0.50, and 0.75 wt% chitosan. The starch type showed a significant effect on the characteristics of resulting aerogels, where aerogels with higher content of amylose showed significantly lower shrinkage and density and higher specific surface area and macroporosity. Furthermore, chitosan addition substantially decreased the shrinkage of the aerogels, particularly those prepared with the dent starch, resulting in aerogels of lower density and higher surface area and macroporous volume. These aerogels were then powdered and employed as oil-absorbing porous materials for structuring soybean oil. Results showed that the aerogels from 55% amylose and 72% amylose starch had better oil structuring capacity compared to those from the dent starch. Furthermore, the starch aerogels supplemented with chitosan showed superior oil structuring ability than the neat starch aerogel counterparts. This work suggests that the starch type and the presence of chitosan had deep impacts on the macroporosity of the starch aerogels and their oil structuring performance.

Effects of the Amylose/Amylopectin Content and Storage Conditions on Corn Starch Hydrogels Produced by High-Pressure Processing (HPP)

In this study, the effects of the amylose/amylopectin content on starch gelation and the physical characteristics of hydrogels produced by HPP were studied by optical and rheological measurements in steady-state conditions. Additionally, the effects of the storage temperature (4 °C and 20 °C) and type of packaging (plastic bags or sealed Petri dishes) on the physical stability of the hydrogels were evaluated for 30 days of storage by evaluating the shrinkage of the granules, as well as the weight loss, water activity, organoleptic, and rheological properties. The experimental findings suggested that amylose plays an antagonistic role in determining the capacity of the starch granules to absorb water under pressure and to create stable and structured gels and on the physical stability of hydrogels due to its influence over the starch retrogradation extent during storage. Twenty per cent amylose was the minimum concentration to form stable corn starch HPP hydrogels with good physical and rheological properties. Moreover, a storage temperature of 20 °C and the use of polymeric bags were evaluated as the most suitable storage conditions and packaging materials enabling the long storage of corn starch hydrogels.

Thermally reversible Mesona chinensis polysaccharide hydrogel

As people become more health conscious, Mesona chinensis polysaccharide-tapioca starch (MCP-TS) hydrogel is attracting considerable attention. Several studies have been conducted on the rheological characteristics and gelling behavior of MCP-TS hydrogel, but very few researches have been performed on their thermal reversibility. In the present study, the thermally reversible characteristics and mechanisms of MCP-TS hydrogels were investigated using rheological tests and Fourier transform infrared spectroscopy. According to thes results, the mechanical characteristics of the MCP-TS hydrogel did not change dramatically after 10 cycles of heating and cooling processes, and hydrogen bonds were important factors that contributed to the formation of MCP-TS hydrogels. In addition, the MCP-TS hydrogel had a high water-holding capacity (more than 98%) and can maintain its shape in water for at least 64 h. Furthermore, the hydrogel demonstrated excellent flexibility, scalability, and durability, which enabled it to bend more than 20 times without breaking. The hydrogels with a high MCP content exhibited desirable mechanical properties, with homogeneous and crosslinked polymer-like networks. However, high MCP concentrations diminished their transparency. These results can pave the way for future applications of MCP-TS hydrogels in the fields of wound dressing and three-dimensional food printing. • Mesona chinensis polysaccharide-tapioca starch (MCP-TS) hydrogel is thermoreversible. • Thermal and cooling cycles did not change the mechanical properties of the hydrogel. • MCP-TS hydrogels exhibited excellent flexibility. • Thermally reversible hydrogels are stabilized primarily by hydrogen bonds.

3D printing-mediated microporous starch hydrogels for wound hemostasis.

Starch hydrogels with biodegradability and cytocompatibility are good alternatives to traditional dressings. Herein, oxidized starch hydrogel loaded with coagulation factor Ca2+ ions (CaOMS) is successfully constructed by green hot-extrusion 3D printing technology (HE-3DP). In vitro study demonstrated the good water absorbing capacity (845.15-1194.20%) and blood cell and platelet adhesion of CaOMS to assist hemostasis owing to the boosted network structure density, gel strength, and the release of activated Ca2+ ions. More importantly, in vivo experiments further demonstrated CaOMS could maintain the weight loss caused by blood loss from wounds and has excellent hemostatic (65 s) and wound healing properties by promoting the secretion of epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF) expression. The advantages of CaOMS, including rapid and effective hemostasis, effective wound healing, low cost, easy usage, and adaptability to fit various wound shapes, make it a promising biomaterial for achieving fast hemostasis and wound healing.

Dough rheological properties, texture, and structure of high-moisture starch hydrogels with different potassium-, and calcium-based compounds

The effects of four kinds of potassium- (potassium alginate, PA; potassium dihydrogen phosphate, KDP) and calcium-based (calcium carbonate, CC; calcium silicate, CSi) compounds on the pasting behavior, rheological properties, microstructure, water mobility, and textural characteristics of pastes, dough, and high-moisture starch hydrogels from potato starch were evaluated. The results showed that the addition of 0.5% CSi, 0.5% CC, 0.4% PA and 0.4% KDP (w/w, total starch basis) significantly improved the tensile strength of high-moisture starch hydrogels compared to that of pure potato starch. Further discussion about the mechanism revealed that the addition of these components could reduce the swelling capacity and peak viscosity of potato starch during heating, further enhance the network structure of the starch dough, and reduce the water mobility thereof, thus contributing to a compact stacking of starch and smaller and denser pore structure of the high-moisture starch hydrogels. This study provides a theoretical basis for the formulation design of alum-free hydrogel derived products.

Effect of Retrograded Starch Hydrogel on the Hygroscopic and Durability Properties of Clay Composites.

This study is devoted to assessing the hygroscopic and durability properties of a clay composite with the addition of a natural polymer. Modified polymer-retrograded starch hydrogel (RSH) of various concentrations (2.5, 5.0, 7.5, and 10.0%) and heating times (3 and 5 h) were used as clay stabilizers. The introduction of retrograded starch tends to increase the drying rate of clay composites at the early period of 0-4 days without the formation of shrinkage defects. Moisture uptake increased by 29% (from 140 to 180 g/m2) over the control clay composite without RSH. The hysteresis rate of the clay samples modified with RSH decreased by half (from 0.3 to 0.15%), but the hygroscopic properties were better. The use of RSH polymer increased the durability (water erosion resistance) of the clay composite. The obtained composite has great potential for indoor use due to its high moisture-regulating and durability properties.

Reactive Extrusion-Assisted Process to Obtain Starch Hydrogels through Reaction with Organic Acids

A totally green process based on reactive extrusion was used for the production of cassava starch hydrogels through reaction with two organic crosslinking agents, citric (CA) and tartaric (TA) acids. CA and TA were used at different concentrations (0, 2.5, 5.0, 10.0, 15.0, and 20.0%). Degree of substitution (DS) of hydrogels ranged from 0.023 to 0.365. Fourier transform infrared spectroscopy results showed a new band appearing at 1730 cm−1 associated with ester carbonyl groups. X-ray diffraction indicated that reactive extrusion resulted in the disappearance of diffraction peaks of native starch and samples with lower crystallinity indices ranging from 37% (native starch) to 8–11% in starch hydrogels. Morphology analysis showed that the original granular structure of starch was lost and replaced by a rougher and irregular structure. Water holding capacity values of starch hydrogels obtained by reactive extrusion were superior to those of native starch and the control sample (extruded without the crosslinking agents). Hydrogels obtained with the highest CA or TA concentration (20.0%) resulted in the higher DS and swelling capacities, resulting in samples with 870 and 810% of water retention, respectively. Reactive extrusion was effective in obtaining starch hydrogels by reaction with organic acids.

Effect of pectic oligosaccharide on probiotic survival and physicochemical properties of hydrogel beads for synbiotic encapsulation of Lactobacillus bulgaricus

The present study was carried out to evaluate the effects of different concentrations of pectic oligosaccharide (POS) on the physicochemical properties of Lactobacillus bulgaricus (L. bulgaricus) loaded-synbiotic hydrogel beads and the survival of L. bulgaricus. Low methoxyl (LM) pectin-resistant starch (RS) hydrogel beads, named RS beads, were coated/filled with different concentrations of POS: 0.8% (RS-POS0.8 beads), 1.0% (RS-POS1.0 beads), and 1.2% (RS-POS1.2 beads). POS treatment resulted in smooth beads with less surface dent by hydrogen bonding between RS beads and POS, which was confirmed by SEM and XRD analyses. The encapsulation efficiency of RS beads and RS-POS beads ranged from 90.40% to 92.03%. In simulated gastric fluid (SGF) and bile salt solution, free L. bulgaricus completely died but L. bulgaricus encapsulated in RS-POS1.2 beads only slightly decreased. This indicates that RS-POS1.2 beads exhibited higher protective effects on L. bulgaricus under SGF condition and bile salts. Furthermore, considering the relatively higher storage stability of L. bulgaricus loaded in RS-POS1.2 beads, the present results suggest that RS beads coated/filled with POS could be used for synbiotic encapsulation, protection, and delivery of probiotics.

Self-compounded, tough biohydrogels for robust self-adhesive biointerfaces

Bio-friendly and sustainable hydrogels of natural origins are attractive alternatives to their synthetic counterparts, offering imaginative opportunities for applications in bioelectronics and biomedical fields. Most biopolymers, however, are intractable and inherently fragile, incapable of proper operation without blending or modifications. Here we report that highly stable and robust pure biohydrogels can be engineered with tissue-like mechanical and electrical properties. By harnessing and controlling the natural gelation process of starches, a strong association between the microstructural evolution and the macroscopic properties of bulk hydrogels is established. Accordingly, tough pure starch hydrogels with a unique self-compounded heterostructure are constructed, showing anti-fatigue properties originating from the dynamic noncovalent hydrogen bonding. Such biohydrogels exhibit instant and reversible self-adhesiveness to assorted materials, securing seamless and reliable interfacing with dynamic wet skins. Wearable strain sensors and epidermal bioelectrodes are successfully demonstrated, exhibiting high sensitivity over a wide strain range and superior biosignal quality with long-term reliability. The multifunctional pure starch hydrogels are completely biodegradable, offering a green and sustainable solution for intimate human-machine interfaces.

Gradient Gels: Exploring Diverse Starch Concentrations in Hydrogel Formulations

Starch hydrogels can be used for both drug formulation and delivery; they have attracted a lot of interest in the pharmaceutical dispensing industry. Four pharmacy students were tasked with creating starch hydrogels in this study, with different concentrations (2%, 4%, 5%, and 10%) to see how concentration affected the hydrogels' chemical and physical characteristics. The goal of this study was to provide important new information about how to optimise starch hydrogel formulations for use in medicine. The students gained an understanding of how concentration affects properties like viscosity, mechanical strength, and transparency by methodically studying these important variables. Furthermore, the investigation examined the impact of environmental variables like pH and temperature on the stability and functionality of the starch hydrogels.

The effects of pH and iron ions on the mechanical properties of pea starch hydrogels

In this study, the network strength of starch hydrogels was improved by adjusting the pH value (3–11.5) and adding iron ions (Fe3+), and the mechanical properties and swelling properties of the hydrogels were improved. The complex modulus of the starch hydrogel with a pH value of 11.5 and containing Fe3+ was above 3400 Pa. SEM showed that the hydrogel structure became more compact with the increase of pH value. In addition, the hardness of the hydrogel increased from 50.29 g at pH 3.0 to 215.1 g at pH 11.5, while the addition of 0.5 mol/L Fe3+ at pH 11.5 promoted a further hardness increase to 301.8 g. Moreover, the swelling rate of the hydrogel decreased from 670.2 % at pH 7.0 to 464.4 % at pH 11.5, and the addition of 0.5 mol/L Fe3+ further decreased the swelling rate to 191.8 %. Overall, the results indicate that the mechanical properties of starch hydrogels can be improved by making simple adjustments to the pH and the iron ion concentrations.

Application of free volume concept and manipulation of network structure parameters for optimum loading of gallic acid in the modified kutki (Panicum sumatrense) millet starch hydrogel matrix

Hydrogels have been widely preferred for their use as nutraceutical/drug delivery vehicles due to the easy manipulation of their network parameters. In this study, gallic acid (GA) was used as a nutraceutical for loading into the optimized lysine modified kutki millet starch (Lys9-KMS) hydrogel. Various ethanol-water mixtures (% v/v) were used to tailor the network parameters and attain a suitable mesh size of the matrix that could withhold GA without compromising its structure. The diffusivity of GA in the solvent (DAB) and Lys9-KMS hydrogel (DG) possessed an inverse relationship with the solvent viscosity. The encapsulation efficiency (80.37%) was observed to be maximum in case of an 80% ethanol-water mixture. A simple and useful approximation was used for the estimation of free volume for loading the number of nutraceutical molecules in the hydrogel matrix without compromising structural integrity. Upon modeling the ratio of diffusivity (DG/DAB) of GA in the matrix to that in solvent against the hydration i.e. (∅p1−∅p), where ∅p is polymer volume fraction, the value of the parameter, Vf,w (free volume per molecule of solvent), was determined as 1.74 Ȧ and a final amount of GA that can be loaded into the gel matrix was found to be 32.11 ± 1.02 mg for 300 mg hydrogels. The validity of the proposed approach was verified from diffusivity studies and showed an insignificant difference (p > 0.05). This approach would avoid uneven loading of the nutraceuticals or ingredients in the polymer matrix and would reduce their wastage during the design of functional foods.

Improving Mechanical Properties of Starch-Based Hydrogels Using Double Network Strategy.

This work aims to improve the mechanical properties of starch-based hydrogels using a double-network (DN) strategy. The single network (SN) starch hydrogel was first prepared using glutaraldehyde as a crosslinker. The compressive properties of the SN hydrogels were influenced by both crosslinker content and crosslinking time. The SN starch hydrogel possessing the best mechanical properties was then fabricated into DN hydrogels. Poly(vinyl alcohol) (PVA) and borax were used as a secondary polymer and a crosslinker, respectively. The PVA–borax complexation partly enhanced the DN hydrogel’s compressive modulus by 30% and its toughness by 39%. DN hydrogels were found to have denser microstructures than SN hydrogels. To be specific, their walls thickened and grew more continuous while their pores shrank. The increased crosslinking density resulted in changes to the microstructure, which were well correlated with their porosity and water uptake capacity. An in vitro cytotoxicity test of the DN hydrogels revealed that they were non-toxic to chondrocytes. This work demonstrated that double networking is a simple but effective strategy for improving mechanical properties of starch-based hydrogels without sacrificing their biocompatibility. This approach can be used to tailor hydrogel properties to fulfill requirements for biomedical applications, such as tissue engineering and other related fields.

Synthesis and Characterization of Novel Patchouli Essential Oil Loaded Starch-Based Hydrogel.

Starch hydrogels are highly available, biocompatible and biodegradable materials that have promising applications in medical and pharmaceutical industries. However, their applications are very limited due to their poor mechanical properties and fragility. Here, we investigated, for the first time, conventional corn and waxy corn starch-based hydrogels for loading patchouli essential oil. The essential oil extracted by supercritical carbon dioxide with a yield reached 8.37 ± 1.2 wt.% (wet sample) at 80 °C temperature and 10 MPa pressure. Patchouli essential oil exhibited a 23 to 28 mm zone of inhibition against gram-positive and gram-negative bacteria. Waxy starch hydrogels had better properties in term of viscosity, water evaporation stability and the delivery of essential oil than conventional starch hydrogels. The viscosity and spreadability of a 6% waxy starch sample were 15,016 ± 59 cP and 4.02 ± 0.34 g·cm/s, respectively, compared with those of conventional starch hydrogel (13,008 ± 29 cP and 4.59 ± 0.88 g·cm/s). Waxy starch-based hydrogels also provided slower in vitro biodegradation behavior and sustained release of essential oil compared with conventional starch hydrogels. All the samples were biocompatible and non-cytotoxic to fibroblast cells; the addition of patchouli essential oil enhances the proliferation of the cells. The enhanced viscosity, good antibacterial and improved biocompatibility results of prepared hydrogels confirm their suitability for wound healing applications.

Impact of fat replacement by a hybrid gel (canola oil/candelilla wax oleogel and gelatinized corn starch hydrogel) on dough viscoelasticity, color, texture, structure, and starch digestibility of sugar-snap cookies

The reduction of fat content is an important issue in the formulation of bakery products. In this work, the fat content in sugar-snap cookies was reduced by replacing a commercial shortening with a hybrid gel (HG). The HG was formed by mixing a canola oil/candelilla oleogel (5 g/100 g) and a gelatinized corn starch hydrogel (5 g/100 g) in a 1:1 ratio. The commercial shortening was replaced (0, 25, 50, 75, and 100%) by HG, achieving a fat content reduction of up to 50%. HG cookies exhibited reduced hardness and improved firmness, their surface color pattern exhibited an increased yellowness and lightness as HG increased. FTIR analysis revealed that the starch contained in the HG cookies was more hydrated and unordered, and the secondary structure of the proteins was less ordered. The starch hydrolysis pattern exhibited two phases that reflected structures with fast and slow hydrolysis rates. As a consequence of the gelatinized starch fraction, the HG cookies showed increased starch digestibility, with the rapidly digestible starch varying from 19.0% for the control cookie to about 43% for the HG cookie with complete shortening replacement. Overall, hybrid gels offer an alternative to commercial shortening use for formulating sugar-snap cookies with lower saturated fat content.

Functional films based on mechanoactivated starch with prolonged release of preservative

Use of active edible films containing an antimicrobial agent - a new method of extending the shelf life of food products. Ensuring the controlled release of the preservative from the film is an urgent task. This work aims to introduce a new environmentally friendly process for the production of antifungal starch films with a prolonged release of a preservative using mechanoactivation in a rotor-stator device (RSD). Active films based on mechanoactivated starch hydrogels containing 0–5.0% (w/w) benzoic acid as a preservative and chitosan as a solubilizing additive (St-BA-Ch), as well as films containing sodium benzoate (St-SB) for comparison, were obtained by the casting method. Films were characterized using optical and atomic force microscopy, X-ray diffraction and tensile and moisture permeability testing data. It was found that benzoic acid is present in the St-BА-Ch-films in the form of submicron particles. St-BА-Ch films showed greater tensile strength and a lower release rate of the preservative into model media compared to St-SB films. It is established that mechanical activation of casting hydrogels in RSD allows increasing the strength films by an average of 2 times, as well as reducing the release rate of the preservative and the vapor permeability of the films. The antifungal activity of the films was confirmed using Aspergillus niger. The developed active St-BА-Ch film can be recommended for use in the food industry to extend the shelf life of food products.

Mechanical, microstructural, and rheological characterization of gelatin-dialdehyde starch hydrogels constructed by dual dynamic crosslinking

Novel gelatin/dialdehyde starch (GDS) hydrogels based on gelatin were prepared using dialdehyde starch as a macromolecular crosslinking agent. Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray diffraction showed that the dynamic hydrogel network was formed by covalent imine bonds and hydrogen bonds between dialdehyde starch and gelatin. The synergistic physical and chemical cross-linking endowed the hydrogels with excellent mechanical properties (maximum compressive stress was 0.55 MPa), fatigue resistance (they maintained their shape after ten compression cycles), toughness (54.6 kN/m2), and self-recoverability of the polymeric network. In the rheological tests, all the storage modulus were higher than loss modulus, indicating that they are elastic gels and not viscous sols. The polymer network of GDS hydrogels could recover rapidly when subjected to oscillating shear strain. In addition, with increasing dialdehyde starch concentration, the hydrogels had higher swelling stability and a denser microstructure. Given these excellent properties, the hydrogels have potential application prospects as cell culture scaffolds and carriers of bioactive substance.

Evaluation of the Physical Stability of Starch-Based Hydrogels Produced by High-Pressure Processing (HPP).

Starch-based hydrogels are natural polymeric structures with high potential interest for food, cosmeceutical, and pharmaceutical applications. In this study, the physical stability of starch-based hydrogels produced via high-pressure processing (HPP) was evaluated using conventional and accelerated methods. For this purpose, conventional stability measurements, namely swelling power, water activity, texture, and organoleptic properties, as well as microbiological analysis of rice, corn, wheat, and tapioca starch hydrogels, were determined at different time intervals during storage at 20 °C. Additionally, to assess the stability of these structures, accelerated tests based on temperature sweep tests and oscillatory rheological measurements, as well as temperature cycling tests, were performed. The experimental results demonstrated that the physical stability of starch-based HPP hydrogels was interdependently affected by the microorganisms’ action and starch retrogradation, leading to both organoleptic and texture modifications with marked reductions in swelling stability and firmness. It was concluded that tapioca starch hydrogels showed the lowest stability upon storage due to higher incidence of microbial spoilage. Accelerated tests allowed the good stability of HPP hydrogels to be predicted, evidencing good network strength and the ability to withstand temperature changes. Modifications of the rheological properties of corn, rice, and wheat hydrogels were only observed above 39 °C and at stress values 3 to 10 times higher than those necessary to modify commercial hydrogels. Moreover, structural changes to hydrogels after cycling tests were similar to those observed after 90 days of conventional storage. Data obtained in this work can be utilized to design specific storage conditions and product improvements. Moreover, the accelerated methods used in this study provided useful information, allowing the physical stability of starch-based hydrogels to be predicted.

Adsorption of Malachite Green from Aqueous Solution Using Hydroxyethyl Starch Hydrogel Improved by Graphene Oxide

This study is the first report of the preparation of hydroxyethyl starch (HES) hydrogels rapidly crosslinked with divinyl sulfone in a single step and single pot. To develop the physical and chemical features of hydrogels, Graphene oxide (GO) nanoparticles were combined with the crosslinked HES. In addition to swelling studies, structural characterization of the samples was conducted with a scanning electron microscope (SEM) and transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD), Brunauer–Emmett–Teller (BET) analysis and thermogravimetric analysis (TGA). For the removal of malachite green model dye by GO-HES, the effects of GO content, solution concentration, temperature, contact duration, dosage and pH on varying adsorption features were researched. Additionally, adsorption isotherms, kinetic and thermodynamic systematics were analyzed. The maximum adsorption capacity of GO-HES composite hydrogel was found to be 89.3 mg/g for Langmuir isotherm. The possible adsorption mechanism of the composite hydrogels for malachite green dye involved electrostatic, hydrogen bonding, and π–π interactions. In addition to reasonable cost and simple synthesis method, the prepared composite materials have potential use in wastewater treatment as adsorbents for the removal of dye from aqueous solutions due to efficient adsorption capacity.