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Spirulina protein isolate (SPI) is a bio-polymer that can be used in the design and synthesis of hydrogels due to its biodegradability and non-toxicity. Herein, dual-crosslinked hydrogels were synthesized based on spirulina protein isolate through covalent crosslinking with genipin and metal coordination with Zn 2+ , and used as delivery systems. From the analysis of colorimetric indices, a high correlation between color changes and the reaction of cross-linkers with amine group structure was observed. By increasing genipin concentration in the range of 5-15 mM, the degree of cross-linking increased up to 83 %. Cross-linked hydrogels, depending on the type and concentration of cross-linkers, had a smooth to rough and dense structure with low porosity. In the FTIR spectra, significant shifts were observed in amide bonds, which are related to the formation of secondary amides after genipin crosslinking. The maximum water absorption capacity (381 %) was obtained at pH 7.4, which was significantly reduced by increasing the concentration of cross-linkers or decreasing the pH of the environment. The release rate of vitamin B6 (model) at pH 2 (45 %) was much lower than at pH 7.4 (65 %) which makes hydrogels suitable for intestinal delivery. Vitamin B6 release data indicated the best fit to the Peppas-Sahlin model in all the cases (98-99 %) and showed that the release process occurs through quasi-Fickian diffusion. The finding reveals that spirulina protein-based hydrogels can potentially be used in the design of practical carriers for the targeted delivery of bioactive compounds., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The main purpose of this study was to increase shelf life of banana using active hydrogel. For this purpose, carboxymethylcellulose/nanofiber cellulose/potassium permanganate (CMC/NFC/KMnO 4 ) hydrogel film was prepared. The morphology and physicochemical properties of CMC hydrogels was investigated. The prepared films were used as humidity/ethylene absorbent in banana packaging for 30 days at 0 and 25 °C. The physical, mechanical and sensory properties of bananas were studied during storage. SEM images confirmed the presence of nanofibers in the hydrogel structure. NFC and KMnO 4 increased the tensile strength of the film and decreased its elongation. On the 15th day of storage, bananas packaged with optimal active hydrogel (CMC/NFC/KMnO 4 ) at 25 °C had a flavor of 3 and a general acceptance of 3.5, while control bananas had a flavor of 0.5 and a general acceptance of less than 1. On the 30th day of storage, bananas packaged with optimal active hydrogel at 25 °C had a toughness of 4 (N·s) and a firmness of 20 (N), while control bananas had a toughness of about 1 (N·s) and a firmness of about 8 (N). On the 30th day of storage, the humidity inside the package of bananas packed with the optimum active hydrogel at 25 °C was 59.5%, while the humidity in the control packages was 85%, indicating that the hydrogel was able to absorb the moisture inside the package. Totally it can be said that CMC/NFC/KmnO 4 hydrogel can increase shelf life of a banana by simultaneously controlling ethylene and humidity in food packaging., (Copyright © 2021. Published by Elsevier B.V.)

The aim of this study was to synthesize Fe3O4 nanoparticles and gluten/pectin/Fe3O4 composite hydrogel. This nano-hydrogel was then used to reduce sediment contamination in Lake Urmia (Iran). For this purpose, magnetic nanoparticles were chemically synthesized. Two types of composite Hydrogels including gluten/Fe3O4 and gluten/pectin/Fe3O4 composites were prepared by adding Fe3O4 nanoparticles and pectin to wheat gluten. The properties of Hydrogels were studied by scanning electron microscopy (SEM), Fourier-transform infrared and X-ray diffraction methods. SEM results showed that Fe3O4 particles were seed shape (30–60 nm). The results confirmed the physical interactions between magnetic nanoparticles, pectin and gluten. Subsequently, the prepared Hydrogels were used to reduce the pollution of Lake Urmia sediments. Central composite design was used to investigate the effect of interaction time and interaction temperature of hydrogel with sediment and the type of hydrogel. Qualitative characteristics of the sediments, including heavy metal concentrations (arsenic, barium, cadmium, lead, mercury and chromium), biochemical oxygen demand, and chemical oxygen demand COD, and organic compounds were investigated before and after treatment of sediments with hydrogel. The effect of hydrogel on enhancing sediment quality was investigated. The results showed that in the optimum condition removal efficiency of total heavy metals was 62% and removal efficiency of total organic compounds was 42%. The results also showed that gluten/pectin/Fe3O4 hydrogel had better performance in reducing environmental pollutants of sediment than wheat gluten/Fe3O4 hydrogel. [ABSTRACT FROM AUTHOR]

In this work a new magnetic nanocomposites based on Fe3O4-Hydrogel and Fe3O4@SiO2-Hydrogel were synthesized. The poly(styrene-alt-maleic anhydride) was used as hydrogel compound. The hydrogel has the strong ability to remove some organic and inorganic compounds like methylene blue from water samples. Fe3O4 nanoparticles have the magnetic character that could help to the separation of hydrogel from the water after removal process by a magnet. The morphology of the hydrogel, Fe3O4, Fe3O4-Hydrogel and Fe3O4@SiO2-Hydrogel was examined by scanning electron microscope (SEM). The structure of hydrogel and presence of the Fe3O4 and SiO2 particles in the hydrogel nanocomposite was verified by FT-IR spectroscopy. The synthesized nanocomposites were used to remove the methylene blue from wastewater samples. Central Composite Design (CCD) and response surface method were used to optimize some parameters that affect the magnetic character, removal ability and removal efficiency, so the time of removal (minute), pH and the amount of hydrogel (mg) as important parameters were optimized by designing experiments. Determination of removal efficiency was done by spectrophotometric method. Results showed that the Fe3O4@SiO2-Hydrogel had the more efficiency than Fe3O4-Hydrogel and the removal efficiency of methylene blue from water by synthesized Fe3O4@SiO2-Hydrogel was between 50–95% that in the optimized condition it was almost 95%. Relative standard deviation (RSD) for 5 replicates the removal of methylene blue with synthesized sorbent was 4%. [ABSTRACT FROM AUTHOR]

• Thymus daenensis essential oils and Glycyrrhizic acid were co-loaded in ß-CD successfully. • Td-EO/GA/ß-CD were co-encapsulated in alginate successfully. • The formation of the Td-EO/GA/ß-CD/Alginate beads was confirmed with structural analysis. • Controlled release of Td-EO and GA in simulated gastric fluid and simulated intestinal fluids were confirmed. In this study, glycyrrhizic acid (GA) (extracted from licorice root) and Thymus daenensis essential oils (Td-EO) were loaded into ß-cyclodextrin (ß-CD) and subsequently, were co-encapsulated with alginate to produce active alginate hydrogel beads. The structural properties, antioxidant activity, and antimicrobial features of alginate hydrogel beads incorporated with GA and Td-EO active ingredients were evaluated. The structural properties of hydrogels were analyzed using FTIR, DSC, SEM, and DLS techniques. FTIR analysis indicated no significant interaction between GA/Td-EO active agents and functional groups of alginate, resulting in an easy release of Td-EO and GA from the hydrogels. A maximum swelling capacity of ∼610.3% was obtained for alginate beads at ambient temperature. The encapsulation efficiency and loading capacity of GA/Td-EO for the hydrogel beads were in a range of between 89.12–94.06, and 1.04–3.12, respectively. Incorporation of GA and Td-EO in hydrogel beads improved antioxidant activity. Investigating the in vitro antibacterial activity of alginate beads against S. aureus (Gram-positive), and E. coli (Gram-negative) showed a high inhibition zone (21.00 ± 1.38 mm) for S. aureus. The release of Td-EO and GA from alginate beads in the simulated gastric fluid (SGF) (pH 1.2) and simulated intestinal fluids (SIF) (pH 7.4) at 37 °C were studied. In the SIF medium, a high rate release of both Td-EO and GA was observed. Release of Td-EO and GA from alginate beads can be considered as a promising candidate in designing intelligent drug carrier with intestinal release activity. [ABSTRACT FROM AUTHOR]