Smart hydrogels based on semi-interpenetrating polymeric networks of collagen-polyurethane-alginate for soft/hard tissue healing, drug delivery devices, and anticancer therapies.

In this work, hydrogels based on semi-interpenetrating polymeric networks (semi-IPN) based on collagen-polyurethane-alginate were studied physicochemically and from different approaches for biomedical application. It was determined that the matrices in the hydrogel state are crosslinked by the formation of urea and amide bonds between the biopolymer chains and the polyurethane crosslinker. The increment in alginate content (0-40 wt%) significantly increases the swelling capacity, generating semi-crystalline granular structures with improved storage modulus and resistance to thermal, hydrolytic, and proteolytic degradation. The in vitro bioactivity results indicated that the composition of these novel hydrogels stimulates the metabolic activity of monocytes and fibroblasts, benefiting their proliferation; while in cancer cell lines, it was determined that the composition of these biomaterials decreases the metabolic activity of breast cancer cells after 48 h of stimulation, and for colon cancer cells their metabolic activity decreases after 72 h of contact for the hydrogel with 40 wt% alginate. The matrices show a behavior of multidose release of ketorolac, and a higher concentration of analgesic is released in the semi-IPN matrix. The inhibition capacity of Escherichia coli is higher if the polysaccharide concentration is low (10 wt%). The in vitro wound closure test (scratch test) results indicate that the hydrogel with 20 wt% alginate shows an improvement in wound closure at 15 days of contact. Finally, the bioactivity of mineralization was evaluated to demonstrate that these hydrogels can induce the formation of carbonated apatite on their surface. The engineered hydrogels show biomedical multifunctionality and they could be applied in soft and hard tissue healing strategies, anticancer therapies, and drug release devices.

Fungal Proteins from Sargassum spp. Using Solid-State Fermentation as a Green Bioprocess Strategy.

The development of green technologies and bioprocesses such as solid-state fermentation (SSF) is important for the processing of macroalgae biomass and to reduce the negative effect of Sargassum spp. on marine ecosystems, as well as the production of compounds with high added value such as fungal proteins. In the present study, Sargassum spp. biomass was subjected to hydrothermal pretreatments at different operating temperatures (150, 170, and 190 °C) and pressures (3.75, 6.91, and 11.54 bar) for 50 min, obtaining a glucan-rich substrate (17.99, 23.86, and 25.38 g/100 g d.w., respectively). The results indicate that Sargassum pretreated at a pretreatment temperature of 170 °C was suitable for fungal growth. SSF was performed in packed-bed bioreactors, obtaining the highest protein content at 96 h (6.6%) and the lowest content at 72 h (4.6%). In contrast, it was observed that the production of fungal proteins is related to the concentration of sugars. Furthermore, fermentation results in a reduction in antinutritional elements, such as heavy metals (As, Cd, Pb, Hg, and Sn), and there is a decrease in ash content during fermentation kinetics. Finally, this work shows that Aspergillus oryzae can assimilate nutrients found in the pretreated Sargassum spp. to produce fungal proteins as a strategy for the food industry.

Insecticidal capacity of polyphenolic seed compounds from neem (Azadirachta indica) on Spodoptera frugiperda (J. E. Smith) larvae.

The objective of this study was to evaluate the insecticidal activity of the polyphenolic compounds found in neem on S. frugiperda larvae. Three neem extracts (1:12 (m/v) with 70% ethanol, 1:12 (m/v) with 0% ethanol (only water), and 1:4 (m/v) with 0% ethanol) were employed. Subsequently, the extraction of phytochemical compounds of each extract was performed using ultrasound and microwave technologies simultaneously. The compound characterization was performed by HPLC-mass. In addition, the insecticidal evaluation of the neem extract was performed against S. frugiperda of the second-stage larvae. The extracts were applied by spraying the larvae according to each bioassay. Results showed that the extract obtained with a 1:12 (m/v) relationship and 70% ethanol was effective for the control of S. frugiperda larvae. In this extract, the predominant organic compound families were: methoxyflavones, flavonols, hydroxycoumarins, anthocyanins, methoxycinnamic acid, and alkylflavones. Phytochemical compounds obtained from neem seeds with environmentally friendly solvents and alternative technologies (ultrasound and microwave) have potent insecticidal activity against S. frugiperda larvae.

Collagen-polyurethane-dextran hydrogels enhance wound healing by inhibiting inflammation and promoting collagen fibrillogenesis.

Diabetic foot ulcers are a serious complication of uncontrolled diabetes, emphasizing the need to develop wound healing strategies that are not only effective but also biocompatible, biodegradable, and safe. We aimed to create biomatrices composed of semi-interpenetrated polymer networks of collagen, polyurethane, and dextran, to enhance the wound healing process. The hydrogels were extensively characterized by various analytical techniques, including analysis of their structure, crystallinity, thermal properties, gelation process, reticulation, degradation, cell proliferation, and healing properties, among others. Semi-interpenetrated hydrogels containing dextran at levels of 10%, 20%, and 30% exhibited porous interconnections between collagen fibers and entrapped dextran granules, with a remarkable crosslinking index of up to 94% promoted by hydrogen bonds. These hydrogels showed significant improvements in mechanical properties, swelling, and resistance to proteolytic and hydrolytic degradation. After 24 h, there was a significant increase in the viability of several cell types, including RAW 264.7 cells, human peripheral blood mononuclear cells, and dermal fibroblasts. In addition, these hydrogels demonstrated an increased release of interleukin-10 and transforming growth factor-beta1 while inhibiting the release of monocyte chemotactic protein-1 and tumor necrosis factor-alpha after 72 h. Furthermore, these hydrogels accelerated the wound healing process in diabetic rats after topical application. Notably, the biomaterial with 20% dextran (D20) facilitated wound closure in only 21 days. These results highlight the potential of the D20 hydrogel, which exhibits physicochemical and biological properties that enhance wound healing by inhibiting inflammation and fibrillogenesis while remaining safe for application to the skin.

Goethite-titania composite: disinfection mechanism under UV and visible light.

Goethite-titania (α-FeOOH-TiO2) composites were prepared by co-precipitation and mechanical milling. The structural, morphological and optical properties of as-synthesized composites were characterized by X-ray powder diffraction, scanning electron microscopy and UV-Vis diffuse reflectance spectroscopy, respectively. α-FeOOH-TiO2 composites and TiO2-P25, as reference, were evaluated as photocatalysts for the disinfection of Escherichia coli under UV or visible light in a stirred tank reactor. α-FeOOH-TiO2 exhibited better photocatalytic activity in the visible region than TiO2-P25. The mechanical activation increased the absorption in the visible range of TiO2-P25 and the photocatalytic activity of α-FeOOH-TiO2. In the experiments with UV light and α-FeOOH-TiO2, mechanically activated, a 5.4 log-reduction of bacteria was achieved after 240 min of treatment. Using visible light the α-FeOOH-TiO2 and the TiO2-P25 showed a 3.1 and a 0.7 log-reductions at 240 min, respectively. The disinfection mechanism was studied by ROS detection and scavenger experiments, demonstrating that the main ROS produced in the disinfection process were superoxide radical anion, singlet oxygen and hydroxyl radical.