Bio-based hydrogel patches made of κ-carrageenan enriched with degalactosylated xyloglucan for wound dressing applications.

Chitosan (CS) is a promising polymeric biomaterial for use in scaffolds forin vitroskin models and wound dressings, owing to its non-antigenic and antimicrobial properties. However, CS often exhibits insufficient physicochemical properties, mechanical strength, and bioactivity, limiting its efficacy in demanding applications. To address these challenges, cotton cellulose nanofibers (CNFs) represent a promising nanomaterial for enhancing CS-based scaffolds in tissue engineering. CNF offers superior stiffness, and mechanical properties that enhance cellular adhesion and proliferation, both crucial for effective tissue regeneration and healing. This study aimed to develop and characterize a scaffold combining cotton CNF and CS, focusing on its cytocompatibility with human fibroblasts and keratinocytes. The cotton CNF/CS scaffold was fabricated using the casting technique, and its physicochemical properties and cellular compatibility were assessedin vitro. The results demonstrated that incorporating cotton CNF significantly enhanced the stability of the CS matrix. The CS scaffold with 1000 μg ml-1of cotton CNF exhibited increased roughness and reduced rupture strain compared to the pure CS scaffold. The cotton CNF/CS scaffold effectively promoted the adhesion, viability, proliferation, migration, and collagen synthesis of skin cells. Notably, increased cell viability was observed in human fibroblasts cultured on scaffolds with higher concentrations of cotton CNF (100 and 1000 μg ml-1). Based on the findings, the cotton CNF/CS scaffold demonstrates enhanced physicochemical properties and bioactivity, making it a promising candidate for the development ofin vitrohuman skin models and wound healing dressings.

Wound healing requires a contamination-free, sterile, and breathable environment. However, to develop an ideal wound dressing with all these functionalities simultaneously poses significant challenges. In this study, we designed a wound dressing that mimics the structure of skin with good breathability and protective functions. The wound dressing consists of a hydrophilic Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) membrane coated with zinc oxide nanoparticles and a hydrophobic polyvinylidene fluoride (PVDF) membrane. Meanwhile, plasma treatment was also utilized to bond the two layers, resulting in an enhancement of 60 % in mechanical properties. The crosslinked fibrous membranes exhibited uniform stress distribution when stretching. Due to the unique structures of the wound dressing, it demonstrates wound exudate management, antibacterial functions, and hemostatic properties. The hydrophobic layer guided wound exudate towards the hydrophilic layer and the zinc oxide nanoparticles acted as a barrier against external bacteria and released zinc ions to inhibit bacterial growth in the exudate. Moreover, the water vapor transmission rate (WVTR) was measured to be over 86.55 kg/m2/day, the hemolysis rate was 2.38 %, and an impressive 81.98 % healing rate was recorded during in vitro wound healing. This skin-mimicking wound dressing shows great potential as a promising solution for the therapy of chronic wounds and infections.

Mechanical properties of electrospun fibrinogen structures

Wound care is a major biomedical field that is challenging due to the delayed wound healing process. Some factors are responsible for delayed wound healing such as malnutrition, poor oxygen flow, smoking, diseases (such as diabetes and cancer), microbial infections, etc. The currently used wound dressings suffer from various limitations, including poor antimicrobial activity, etc. Wound dressings that are formulated from biopolymers (e.g., cellulose, chitin, gelatin, chitosan, etc.) demonstrate interesting properties, such as good biocompatibility, non-toxicity, biodegradability, and attractive antimicrobial activity. Although biopolymer-based wound dressings display the aforementioned excellent features, they possess poor mechanical properties. Gelatin, a biopolymer has excellent biocompatibility, hemostatic property, reduced cytotoxicity, low antigenicity, and promotes cellular attachment and growth. However, it suffers from poor mechanical properties and antimicrobial activity. It is crosslinked with other polymers to enhance its mechanical properties. Furthermore, the incorporation of antimicrobial agents into gelatin-based wound dressings enhance their antimicrobial activity in vitro and in vivo. This review is focused on the development of hybrid wound dressings from a combination of gelatin and other polymers with good biological, mechanical, and physicochemical features which are appropriate for ideal wound dressings. Gelatin-based wound dressings are promising scaffolds for the treatment of infected, exuding, and bleeding wounds. This review article reports gelatin-based wound dressings which were developed between 2016 and 2021.

Wound healing is a dynamic and complex process in which the microenvironment at the wound site plays an important role. As a common material for wound healing, dressings accelerate wound healing and prevent external wound infections. Hydrogels have become a hot topic in wound-dressing research because of their high water content, good biocompatibility, and adjustable physical and chemical properties. Intelligent hydrogel dressings have attracted considerable attention because of their excellent environmental responsiveness. As smart polymer hydrogels, thermosensitive hydrogels can respond to small temperature changes in the environment, and their special properties make them superior to other hydrogels. This review mainly focuses on the research progress in thermosensitive intelligent hydrogel dressings for wound healing. Polymers suitable for hydrogel formation and the appropriate molecular design of the hydrogel network to achieve thermosensitive hydrogel properties are discussed, followed by the application of thermosensitive hydrogels as wound dressings. We also discuss the future perspectives of thermosensitive hydrogels as wound dressings and provide systematic theoretical support for wound healing.

CO20 - Prise en charge medico-chirurgicale de l’orbitopathie dysthyroidienne : a propos de 40 cas

A self-healing and injectable oxidized quaternized guar gum/carboxymethyl chitosan hydrogel with efficient hemostatic and antibacterial properties for wound dressing

Sulfated polysaccharides are structurally diverse biomolecules with broad applications across the medical, pharmaceutical, and food industries. They are used in drug delivery systems, wound dressings, anticoagulants, tissue engineering scaffolds, and as stabilisers or thickeners in food and cosmetic formulations. The functional properties of these complex biopolymers are closely linked to structural features including molecular weight, monosaccharide composition, glycosidic linkages, and sulfation patterns. However, this structural complexity presents significant challenges for detailed structural characterisation, requiring the use of advanced, complementary analytical techniques specifically suited to their complex structures. Research described in this thesis focused on the detailed structural characterisation of two naturally occurring sulfated polysaccharides, carrageenan and heparan sulfate, with the specific aims of: 1. Advancing our understanding of carrageenan structures from the Gigartinaceae family, and 2. Developing chemical strategies for preparing and analysing structurally informative disaccharides from heparan sulfate. Carrageenans are sulfated polysaccharides produced by red seaweeds. In this research, carrageenans from two species of Rhodoglossum were extracted and characterised: Rhodoglossum sp., collected in New Zealand, and R. gigartinoides, collected in Australia. Both species belong to the Gigartinaceae family and are closely related, as indicated by rbcL sequence data. Carrageenans from the gametophytic (haploid) and tetrasporophytic (diploid) life stages of both species were characterised using a combination of chemical derivatisation, chromatography, and spectroscopy techniques. Similar to other members of the Gigartinaceae, the different life stages of these species were found to produce different types of carrageenans. The gametophytes of both Rhodoglossum species were shown to contain κ/ι-hybrid type carrageenans. The tetrasporophytes contained λ-type carrageenans which included π, ξ, and a modified ξ-type carrageenan having a higher sulfate content. Carrageenans from tetrasporophytic plants of R. sp. and R. gigartinoides differed in the proportion of ξ and modified ξ-type carrageenans. These carrageenans have similar structures to those of other closely related endemic New Zealand species of the Gigartinaceae, supporting the use of carrageenan structures as chemotaxonomic markers. In continuation of the investigation into sulfated polysaccharides, chemical strategies were explored for generating disaccharides from heparan sulfate, a glycosaminoglycan found in animal tissues. The first approach involved butanolysis, which preserves uronic acid epimers but results in the loss of sulfate and acetyl groups. UPLC–MS analysis revealed a complex mixture of monomers, disaccharides, and longer oligosaccharides. The disaccharides generated through this approach were subsequently characterised. The second approach adapted a methylation methodology, commonly used for plant polysaccharides, to facilitate the formation of disaccharides from which information on sulfation pattern could be inferred. This strategy involved carboxyl reduction, permethylation, acid-catalysed cleavage, and subsequent acetylation to produce derivatives amenable to GC–MS analysis. Hydrolysis of carboxyl-reduced, permethylated HS using TFA was not suitable for the intended purpose. In contrast, methanolysis yielded disaccharides as the major products, however; not in the proportions expected. The results demonstrated that the application of this methodology to glycosaminoglycans is feasible, but the complexity of the chemical processing involved necessitates further work before it can be used as a diagnostic analytical tool.

Multifunctional chitosan/carbon dots/sodium alginate/zinc oxide double-layer sponge hydrogel with high antibacterial, mechanical and hemostatic properties

The chronic wound treatment often includes debridement, cleaning of the wound and wound dressing. When a trauma occurs, the injured skin should be instantly covered with a wound dressing which could maintain a moderately moist environment for skin regeneration, remove excessive exudates, alleviate pain and prevent infection. The dressing material should preferably satisfy the following requirements: softness and flexibility, high mechanical strength and elasticity, physical and chemical stability, biocompatibility/biodegradability, antibacterial and anti-inflammatory properties and facile applicability. Additionally, wound dressings should be effortlessly sterilized, be cost-effective and have a long shelf life. Existing commercially available wound dressings can only meet a few of the aforementioned specifications. Therefore, novel frontiers for wound dressings should include multi-functional antimicrobial strategies capable of overcoming the present challenges, providing critical cellular components to enhance angiogenesis, and promote wound healing. These should be appropriate for treating impaired and difficult-to-heal wounds, such as diabetic ulcers, and ensure faster healing via reduction of infection, prevention of hypoxia, stimulation of the healing mechanisms, speed up of wound closure, and reduction of scar formation.In this respect, Frontiers in Bioengineering and Biotechnology (Section Biomaterials) developed a Research Topic titled "Biomaterials for Chronic Wound Healing" which was co-edited by M. Vamvakaki, C. Tamerler and O. Kammona (2024). Nine papers were submitted to this Research Topic, of which four were accepted and published (Reviews, N = 3; Original Research, N = 1).Advancements in materials science and tissue engineering led to the design and production of novel wound dressings based on natural or synthetic biomaterials and/or their combinations, aiming to accelerate the wound healing process. These novel dressings are characterized by biocompatibility/biodegradability, minimal toxicity, durability, hydrophilicity, increased absorption/permeability, antimicrobial properties, and enhanced capacity for skin tissue repair. Ansari and Darvishi (2024) presented the requirements for an efficient wound dressing and the different stages of wound healing. They subsequently reviewed various natural biomaterials such as silk, fibrin, collagen, hyaluronic acid, gelatin, N-acetylglucosamine with respect to their sources, synthesis processes and usage in wound dressings. Furthermore, they reviewed common synthetic biomaterials and provided their properties including biocompatibility, biodegradability, bioabsorbability, toxicity and covered their synthesis and modifications with different molecules. The authors summarized the quality control techniques and covered in vitro, ex vivo and in vivo quality assays for validations of their effectiveness when produced as wound dressings.The next topics covered in this issue were based on hydrogels. Hydrogels have a healing effect on wounds due to their moisturizing, cooling and pain-relieving ability. Among them, hydrogels based on gelatin methacrylamide (GelMA) exhibit significant potential for skin tissue engineering owing to their tunable and favorable properties and their similarity to the ECM of skin. GelMA hydrogels can efficiently promote wound healing and skin tissue remodeling via reduction of inflammation, facilitation of vascularization, and support of cell growth. Zhang and coworkers (2023) reviewed the application of GelMA-based hydrogels in wound dressings, skin tissue engineering and transdermal drug delivery. Liang and coworkers (2023) designed and developed GelMA-based wound dressings encapsulating antibacterial polypeptides and MXene nanoparticles (NPs). The composite hydrogels were characterized by enhanced swelling ratio and mechanical strength, antibacterial properties and effective degradation rate. They were also shown to promote cell proliferation and adhesion in vitro and to accelerate wound closure, reduce inflammation and speed up epithelial formation and maturation in vivo. In conclusion, the newly developed hydrogels were found to exhibit superior tissue regeneration ability.The final topic was focused on the stimuli responsive hydrogels. Rapid and efficient healing of maxillofacial and oral trauma is a major concern to both clinicians and patients. Functional hydrogels capable of delivering various cargos that promote wound healing, such as small-molecule drugs, cytokines, nucleic acids, exosomes, stem cells and nanomaterials, have been found to have a positive effect on the healing of maxillofacial and oral injuries. Apart from targeted and controlled release of active agents, multifunctional drug-delivery hydrogels play an active role in stimulating wound healing and have demonstrated unique performance in wound dressings via their adhesive, hemostatic, antioxidant, anti-inflammatory, angiogenic and antibacterial properties, their ability to promote re-epithelialization and effectively seal wounds (Figure 1). Additionally, functional hydrogels are capable of responding to variations in temperature, pH, light, reactive oxygen species and light to release active agents, thus enabling accurate treatment. In this respect, Hao and co-workers (2023) described the structure of the oral mucosal and its healing process, and summarized the presently available stimuli-responsive hydrogels that are used as wound healing promoters.

Dialyzed tilapia skin collagen sponge (DTSCS) and self-assembled tilapia skin collagen sponge (STSCS) were prepared by freeze-drying. The raw components used in the fabrication of DTSCS and STSCS were separated and purified from tilapia fish skin. It is anticipated that these collagen sponges could be developed into medical dressings for hemostasis and wound healing. The aim of the present research was to explore the possibility of DTSCS and STSCS as medical dressings and compare their differences by scanning electron microscopy (SEM), water absorption measurement, differential scanning calorimetry (DSC), measurement of porosity, cytotoxicity, hemolysis, in vivo biocompatibility, and evaluation of hemostatic performance and wound healing. The results indicate that DTSCS and STSCS are suitable materials for use in medical applications with a loose and porous structure, high water absorption, high porosity, and high thermal stability. The materials also displayed good biocompatibility, including excellent blood compatibility, a lack of cytotoxicity, with no apparent rejection following implantation. STSCS exhibited rapid hemostasis and promoted healing, with slightly greater efficacy than DTSCS. The hemostatic properties and promotion of healing in DTSCS was similar to that of commercial bovine collagen sponge. Therefore, DTSCS and STSCS both represented excellent potential candidate materials for use as hemostatic agents and wound dressings.

The authors conducted an extensive literature search of the Science Direct, Scopus, PubMed, and Web of Science databases. Published studies and original articles published in reputed peer-reviewed journals reporting original research were considered. Different wound dressings show different properties and may have different applications depending on the types of wounds. Traditional wound dressings (like gauze), mainly used for clean and dry wounds with mild exudate, are cheap and affordable, however, they suffer from many limitations; including adherence to the skin, pain in removal, contamination with bacteria, and other obstacles. On the other hand, modern dressings have many advantages, such as the fact that they do not adhere to the wound, they are easily removed, and many other advantages. The introduction of nanotechnology in the field has accelerated the discovery and the applications, and many new pharmaceutical products for wound treatment will enter the market soon. Therefore, evaluating the advantages and limitations of different types of dressings and determining a suitable type of wound dressing to be applied is crucial. This article aims to explain the different types of wound healing agents or dressings available to treat acute or chronic wounds.

Lepidium sativum L. (Garden cress/Hab El Rashad) (Ls), family Brassicaceae, has considerable importance in traditional medicine worldwide because of its antioxidant and anti-inflammatory activities. Ls fruits were used in Ayurvedic medicines as a useful drug for injuries, skin, and eye diseases. The aim of this study was to examine the effectiveness of the total ethanol extract (TEE) and polysaccharide (Poly) of Ls seeds loaded on poly(vinyl alcohol) (PVA) nanofibers (NFs) as a wound healing dressing and to correlate the activity with the constituents of each. TEE and Poly were phytochemically analyzed qualitatively and quantitatively. Qualitative analysis proved the presence of phenolic acids, flavonoids, tannins, sterols, triterpenes, and mucilage. Meanwhile, quantitative determinations were carried out spectrophotometrically for total phenolic and total flavonoid contents. High-performance liquid chromatography (HPLC) for TEE identified 15 phenolic acids and flavonoid compounds, with gallic acid and catechin as the majors. Separation, purification, and identification of the major compounds were achieved through a Puriflash system, column Sephadex LH20, and spectroscopic data (1H, 13C NMR, and UV). Eight compounds (gallic acid, catechin, rutin, kaempferol-3-O-rutinoside, quercetin-3-O-rhamnoside, kaempferol-3-O-rhamnoside, quercetin, and kaempferol) were obtained. Gas–liquid chromatography (GLC) analysis for Poly identified 11 compounds, with galactose being the main. The antioxidant activity for both extracts was measured by three different methods based on different mechanisms: 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing ability of plasma (FRAP), and 3-ethylbenzothiazoline-6-sulfonic acid (ABTS). TEE has the highest effectiveness as an antioxidant agent with IC50 82.6 ± 8.35 μg/mL for DPPH and 772.47 and 758.92 μM Trolox equivalent/mg extract for FRAP and ABTS, respectively. The PVA nanofibers (NFs) for each sample were fabricated by electrospinning. The fabricated NFs were characterized by SEM and Fourier transform infrared spectroscopy (FTIR); the results revealed successful encapsulation of TEE and Poly in the prepared NFs. Moreover, the swelling index of TEE in the prepared NFs shows that it is the most appropriate for use as a wound dressing. Cytotoxicity studies indicated a high cell viability with IC50 216 μg/mL and 1750 μg/mL for TEE and Poly, respectively. Moreover, the results revealed that nanofibers possess higher cell viability compared to solutions with the same sample quantities: 9-folds for TEE and 4-folds for Poly of amount 400 μg. The in vitro wound healing test showed that the TEE nanofibers performed better than Poly nanofibers in accelerating wound healing, with 90% for TEE, more than that for the Poly extract (82%), after 48 h. These findings implied that the incorporation of TEE in PVA nanofibers was more efficient than incorporation of Poly in improving the biological activity in wound healing. In conclusion, the TEE and polysaccharides of L. sativum L seed are ideal candidates for nanofibrous wound dressings. Furthermore, the contents of phenolic acids and flavonoids in TEE, which have potential antioxidant activity, make the TEE of L. sativum more favorable for wound healing dressing.

The rapid advancement in modern biofabrication technologies is driven by escalating demands across various key areas of biomedical research and application. Central to these developments is three-dimensional (3D) bioprinting, a technology that enables the precise deposition of cells, biomaterials, and biofactors in 3D space. This technique is crucial for constructing complex biological models and engineered living systems. It plays a pivotal role in biofabrication, with various applications in tissue engineering, disease modeling and etiology, drug screening, and personalized medicine. However, many significant challenges still persist in bioprinting. One major hurdle is the bioprinting of biomimetic constructs that reproduce the complexity, mechanical properties, resolution, and functionality of natural tissues. As the size of bioprinted constructs increases, maintaining their structural integrity and achieving high resolution becomes increasingly difficult. Another fundamental challenge lies in maintaining a balance between high-quality printability with bioinks and ensuring high cell viability throughout the printing process. Gelatin methacryloyl (GelMA) based bioink has been explored in numerous application settings owing to its favorable biochemical characteristics, there is still a lack of understanding regarding how GelMA synthesis parameters influence the material properties of GelMA and how its time and temperature dependent rheological properties, as well as batch differences further impact its applications in extrusion-based bioprinting. The tunable mechanical properties, high water content, and photocrosslinking capabilities of GelMA highlight its potential for localized drug delivery applications, such as in wound dressings or drug-loaded implants that require customization in shape and size. Previous research has shown success in incorporating minocycline (MH) into GelMA scaffolds for therapeutic applications but achieving prolonged and sustained release of MH is challenging due to its small molecular size. Furthermore, the current limitations in speed, precision, and reproducibility necessitate labor-intensive and iterative experiments in 3D bioprinting research. These experiments involve intricate tasks such as Computer-aided design (CAD) model creation, formulation of suitable bioinks, fine-tuning printer parameters, ensuring consistent printability, and assessing cytocompatibility. As a result, the costs and investments associated with bioink development remain significant. The objective of this thesis research is to develop novel GelMA hydrogel bioinks and explore their applications in 3D bioprinting and cellular protection under oxidative stress. We have systematically investigated the impact of synthesis reaction parameters on the properties of GelMA, such as its degree of substitution and molecular weight, and further examined how these properties influence printability. The second objective involves the application of machine learning techniques to optimize the bioprinting process, with a focus on enhancing efficiency and reducing costs. Finally, the third objective of this research is to develop an accessible bioprinted in vitro model utilizing GelMA bioink. This model is specifically designed to assess the effectiveness of minocycline, released from nanoparticle complexes embedded within GelMA scaffolds, in providing cellular protection under oxidative stress conditions. By addressing existing challenges and venturing into novel applications of GelMA based bioinks, this research seeks to contribute significantly to the advancement of 3D bioprinting technology and its potential in various biomedical applications.

Biodegradable synthetic elastomers with tunable mechanical and physicochemical properties remain attractive materials for soft tissue engineering. We have recently synthesized novel poly(1,3-diamino-2-hydroxypropane-co-glycerol sebacate)-co-poly(ethylene glycol) (APS-co-PEG) biodegradable elastomers. This class of PEGylated elastomers has widely tunable mechanical and degradation properties compared wtih currently available biodegradable elastomers. To further investigate the biological application of this class of elastomers, we fabricated hybrid APS-co-PEG/polycaprolactone (PCL) porous scaffolds by electrospinning. The fiber morphology, chemical composition, mechanical properties, degradability, and cytocompatibility of hybrid APS-co-PEG/PCL electrospun scaffolds were characterized. These scaffolds exhibited a wide range of mechanical properties and similar cytocompatibility to PCL scaffolds. Importantly, PEGylation inhibited platelet adhesion on all APS-co-PEG/PCL electrospun scaffolds when compared with PCL and APS/PCL scaffolds, suggesting a potential role in mitigating thrombogenicity in vivo. Additionally, APS-25PEG/PCL scaffolds were found to be mechanically analogous to human heart valve leaflet and supported attachment of human aortic valve cells. These results reveal that hybrid APS-co-PEG/PCL scaffolds may serve as promising constructs for soft tissue engineering, especially heart valve tissue engineering. Copyright © 2017 John Wiley & Sons, Ltd.