Search

Coral reefs are threatened by climate change and the effects of human activity on the marine environment. Researchers are attempting to rescue this fragile ecosystem through coral restoration actions, and a common step in these procedures is transplanting the new coral colonies into coral reefs. To do that, commercial concrete or epoxy resins, also called putty, are utilized, highlighting different concerns about their mechanical and hardening performances and their impact and fate once released into the environment. Hence, this study presents a new biodegradable epoxidized soybean oil acrylate (ESOA)/zein-based coral putty capable of quick hardening underwater as an ecofriendly alternative for transplantation of new coral colonies in the reef. Coral putty is composed of two components, containing one a radical initiator and the other a radical accelerator. Once the two components are mixed, coral putty becomes hard underwater in 20–25 min, showing a hardening timescale much faster than other commercial products. The coral putty is biocompatible when applied to the coral Stylophora pistillata in aquaria and Acropora tenuis corals are out-planted on the reef in the Maldives, demonstrating how this new class of vegetable-oil-based materials can be a more sustainable alternative to epoxy resins commonly used in coral restoration procedures.

Here, the development of highly porous colorimetric indicators that are able to rapidly sense the presence of amine vapors is presented. Specifically, porous, curcumin-loaded polycaprolactone fibers are formed by electrospinning through non-solvent-induced phase separation. In comparison to the non-porous fibers, the developed system shows significantly higher sensitivity and responsivity to the presence of dimethylamine vapors, with a distinct color change at very low vapor concentrations (2.33 ppm compared to 9.26 ppm) within the first 5 s of exposure. Indeed, CIELAB analysis proves that the induced color changes can be easily perceived visually, as the differences between the initial and the final color of the indicator after its interaction with the modified environment are well above the limit for visual perception, even by inexperienced users. Furthermore, the color changes are reversible, enabling the use of the same indicator several times, making it, thus, a sustainable colorimetric indicator system that can be used in applications where the rapid detection of low concentration of alkaline vapors is necessary.

This review explores the colorimetric indicators based on anthocyanin polymer composites fabricated in the last decade, in order to provide a comprehensive overview of their morphological and compositional characteristics and their efficacy in their various application fields. Notably, the structural properties of the developed materials and the effect on their performance will be thoroughly and critically discussed in order to highlight their important role. Finally, yet importantly, the current challenges and the future perspectives of the use of anthocyanins as components of colorimetric indicator platforms will be highlighted, in order to stimulate the exploration of new anthocyanin sources and the in-depth investigation of all the possibilities that they can offer. This can pave the way for the development of high-end materials and the expansion of their use to new application fields.

Malva sylvestris (MS) is a medicinal herb known worldwide for its beneficial effects due to the several active molecules present in its leaves and flowers. These compounds have shown antioxidant and anti-inflammatory properties and thus can be helpful in treatments of burns and chronic wounds, characterized mainly by high levels of free radicals and impairments of the inflammatory response. In this work, we propose bilayer films as wound dressings, based on poly(vinylpyrrolidone) (PVP) and sodium alginate loaded with M. sylvestris extracts from leaves and flowers and fabricated by combining solvent-casting and rod-coating methods. The top layer is produced in two different PVP/alginate ratios and loaded with the MS flowers' extract, while the bottom layer is composed of PVP and MS leaves' extract. The bilayers were characterized morphologically, chemically, and mechanically, while they showed superior self-adhesive properties on human skin compared to a commercial skin patch. The materials showed antioxidant activity, release of the bioactive compounds, and water uptake property. Moreover, the anthocyanin content of the flower extract provided the films with the ability to change color when immersed in buffers of different pH levels. In vitro tests using primary keratinocytes demonstrated the biocompatibility of the MS bilayer materials and their capacity to enhance the proliferation of the cells in a wound scratch model. Finally, the best performing MS bilayer sample with a PVP/alginate ratio of 70:30 was evaluated in mice models, showing suitable resorption properties and the capacity to reduce the level of inflammatory mediators in UVB-induced burns when applied to an open wound. These outcomes suggest that the fabricated bilayer films loaded with M. sylvestris extracts are promising formulations as active and multifunctional dressings for treating skin disorders.

Polyvinylpyrrolidone (commonly known as povidone or PVP) rapidly dissolves in water. This significantly hinders its use in sustained release formulations developed for the biomedical field. Electrospun fibers of PVP dissolve even faster due to larger surface to volume ratio. In this work, we propose a way to circumvent this problem by developing and using functional fibrous materials in hydrogel form. In particular, we demonstrate that ethanolic solutions of PVP containing two hydroxycinnamic acid derivatives, namely p-coumaric and ferulic acids could be electrospun into functional hydrogel fiber mats. After electrospinning, the formed composite mats were first thermally treated at 130 °C for 20 h and subsequently were immersed in aqueous media, where they turned into hydrogels. Thermal annealing did not degrade hydroxycinnamic acid derivatives, preserving their functionality. We propose these hydrogel fiber mats as potential wound dressings and to that end, in vitro tests showed up to 8 days of antioxidants’ release, and consequent protection of A549 epithelial cells against oxidative stresses. Biocompatibility tests using human red blood cells, A549 and HaCaT cell lines indicated no adverse effects. Model studies of mice skin burns induced by UV-B radiation showed that the hydrogel fiber dressings significantly reduced the levels of matrix metallopeptidase, (MMP-9), and glutathione peroxidase 1 (GPX-1), which are usually upregulated by reactive oxidative species on burnt skin. Finally, ex-vivo human skin investigations demonstrated skin regeneration and control of the inflammatory phase as indicated by low levels of pro-inflammatory cytokines (IL-6 and IL-8). Therefore, our outcomes indicate that the developed PVP-based fiber hydrogels, produced using a simple protocol, are promising candidates for active wound dressings.

Microalgae are generally considered an excellent source of vitamins, minerals, and bioactive molecules that make them suitable to be introduced in cosmetics, pharmaceuticals, and food industries. Aphanizomenon flos-aquae (AFA), an edible microalga, contains numerous biomolecules potentially able to prevent some pathologies including age-related disorders. With the aim to include an AFA extract (Klamin®) as a functional ingredient in baked products, we investigated if its bioactive molecules are destroyed or inactivated after standard cooking temperature. The AFA extract was exposed to heat stress (AFA-HS), and no significant decrease in pigment, polyphenol, and carotenoid content was detected by spectroscopic analysis. Thermal stability of AFA-HS extract was demonstrated by thermogravimetric analysis (TGA), and no change in the morphology of the granules of the powder was noticed by SEM microscopic observation. By Folin-Ciocalteu, ORAC, and ABTS assays, no change in the antioxidant activity and polyphenol contents was found after high-temperature exposition. When added in cell culture, solubilized AFA-HS lost neither its scavenging ability against ROS generation nor its protective role against Abeta, the main peptide involved in Alzheimer's disease. Prebiotic and antioxidant activities of AFA extract that are not lost after thermal stress were verified on E. coli bacteria. Finally, AFA-HS cookies, containing the extract as one of their ingredients, showed increased polyphenols. Here, we evaluate the possibility to use the AFA extract to produce functional food and prevent metabolic and age-related diseases.