Chitosan, a biopolymer derived from chitin, exhibits significant antifungal properties, making it a valuable compound for various applications in agriculture food preservation, and biomedicine. The present study aimed to assess the antifungal properties of chitosan-modified films using sol-gel derivatives (CS:ZnO) or graphene-filled chitosan, (CS:GO and CS:rGO) against two strains of fungi that are the most common cause of food spoilage:
Abstract This study aims at elucidating the role of the polysaccharide skeleton (alginate versus chitosan) during the growth and shaping of HKUST‐1 as porous beads. Although the two biopolymers afford an open porous hydrogel network, the freeze‐drying step was crucial with water medium being inappropriate to preserve the crystalline framework of HKUST‐1. Alternatively, drying in ethanol circumvented this drawback by keeping intact the structure of HKUST‐1. However, a contrasting behavior was observed in the resulting polysaccharide@HKUST‐1 beads, as HKUST‐1 grown in alginate underwent a dramatic collapse, whereas self‐standing, open porous microspheres could be obtained using the chitosan templating route. The resulting chitosan@HKUST‐1 cryogel displays an enhanced CO 2 capture (2.67 mmol.g −1 ) compared to its analogs shaped by alginate, making consequently chitosan a better option for structuring MOF‐based adsorbents.
Dendrimers and silica inorganic materials are two effective building blocks that have attracted growing interest in both fundamental and applied material chemistry. The fruitful association of these soft and hard skeletons resulted in an unlimited library of materials and nanodevices with different tailored properties. The aim of this review is to shed light on different strategies of combination of dendrimer–silica materials. Special attention has been accorded to the porosity control and the accessibility of the functional groups of these organic–inorganic hybrid mesoporous materials.
The recent COVID-19 pandemic has triggered an avalanche of research seeking powerful antibacterial and antiviral material-based technologies. Herein, we report the cross-linking of chitosan fishery waste using three different aldehyde-terminated viologens to design iono-functional, shapeable biobased antiseptic hydrogels. Structural investigation has corroborated the presence of the cross-linked cationic 4,4′-bipyridium motif inside and confirmed its accessibility to the guests through chemical reduction. The network can be moreover cross-linked with the simultaneous entrapment of gold, silver, and copper nanoparticles, enabling the accommodation of additional synergistic functionalities inside of the framework. The multifaceted character of the resulting soft hydrogel network is illustrated through its use as a spray to coat glassy surfaces, its casting to deliver transparent and flexible micrometer-thick films, and its coagulation to provide open porous microspheres. Interesting antibacterial activity has been noticed for the cross-linking films, owing to the presence of cationic viologen, with the inhibitory effect being more significant for negative-gram bacteria compared to positive-gram bacteria. Within the two series, the trend in the biological response correlates with increasing the number of the viologen units and/or the engaged molar ratio with respect to native chitosan films. A maximum inhibitory effect of 85% was recorded for negative-gram bacteria, while 50% inhibition was the best performance reached for positive-gram bacteria. Significant amplification of the antibacterial activity has been further noticed using transparent films entrapping a tiny amount of metal nanoparticles (gold, silver, and gold), outperforming holistically those entrapping metal nanoparticles without cross-linking. Specifically, gold nanoparticles grown within the reticular viologen-containing framework enabled the highest antibacterial activity (98% inhibition for negative-gram bacteria and 75% inhibition for positive-gram bacteria), contrasting with a very negligible side effect in terms of hemolytic activity. The straightforwardness, biodegradability, and cost-effectiveness of the disclosed approach open great possibilities toward large-scale use as an antiseptic spray for surface-coating against nosocomial infections.
Marine polysaccharides are believed to be promising wound-dressing nanomaterials because of their biocompatibility, antibacterial and hemostatic activity, and ability to easily shape into transparent films, hydrogels, and porous foams that can provide a moist micro-environment and adsorb exudates. Current efforts are firmly focused on the preparation of novel polysaccharide-derived nanomaterials functionalized with chemical objects to meet the mechanical and biological requirements of ideal wound healing systems. In this contribution, we investigated the characteristics of six different cellulose-filled chitosan transparent films as potential factors that could help to accelerate wound healing. Both microcrystalline and nano-sized cellulose, as well as native and phosphorylated cellulose, were used as fillers to simultaneously elucidate the roles of size and functionalization. The assessment of their influences on hemostatic properties indicated that the tested nanocomposites shorten clotting times by affecting both the extrinsic and intrinsic pathways of the blood coagulation system. We also showed that all biocomposites have antioxidant capacity. Moreover, the cytotoxicity and genotoxicity of the materials against two cell lines, human BJ fibroblasts and human KERTr keratinocytes, was investigated. The nature of the cellulose used as a filler was found to influence their cytotoxicity at a relatively low level. Potential mechanisms of cytotoxicity were also investigated; only one (phosphorylated microcellulose-filled chitosan films) of the compounds tested produced reactive oxygen species (ROS) to a small extent, and some films reduced the level of ROS, probably due to their antioxidant properties. The transmembrane mitochondrial potential was very slightly lowered. These biocompatible films showed no genotoxicity, and very importantly for wound healing, most of them significantly accelerated migration of both fibroblasts and keratinocytes.
The co-condensation of functional alkoxysilanes with tetraethoxysilane in the presence of a structure directing agent under sol-gel process chemistry is a common way to access functional organosilica with an ordered mesostructure. In this report, bulky silylated fatty acid methyl esters were used both as co-templating bio-molecules and functionalizing agents in the process of supra-molecular silica mineralization. The highest structural regularity in terms of pore size distribution and channel size homogeneity was observed for carboxy-tethered silica possessing SBA-15-type architecture due to an enhanced fatty acid precursor-surfactant interaction. The carboxylic surface embedded within the hydrophobic environment of the fatty compounds confers to these materials interesting reactive-surface properties with promising applications as drug-delivery systems and bio-catalytic nanoreactors.
Novel silicates were prepared by using silylated natural fatty acids (derived from triglyceride renewable oils) as co-condensing reagents in presence of tetraethyl orthosilicate (TEOS) and the triblock copolymer, pluronic P123, as a structure directing agent. A series of carboxylic acid functionalized SBA-15-type mesoporous silicates were obtained with tunable nanoscopic order and reactive functional groups that allow the conjugation of amino probes by peptide coupling. Photophysical studies of the covalently linked aminopyrene substantiated that the internal framework of these materials have pronounced hydrophobicity. Moreover, phase separation that can emanate from the bulkiness of the starting fatty silanes has been ruled out owing to the absence of excimers after aminopyrene grafting. The hemotoxicity, cytotoxicity, and antimicrobial activity of these novel silicates were then evaluated. Without discrimination, the functionalized silicates show a significant decrease of red blood cell hemolysis as compared to bare SBA-15-silica material. Within the modified silicate series, germanium-free mesoporous silicates induce only a slight decrease in cell viability and, more interestingly, they exhibit negligible hemolytic effect. Moreover, increasing their concentration in the medium reduces the concentration of released hemoglobin as a result of Hb adsorption. Promising antimicrobial properties were also observed for these silicates with a slight dependency on whether phenylgermanium fragments were present within the silicate framework.
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