Fabrication of bioinspired chitosan/gelatin/allantoin biocomposite film for wound dressing application

Antibacterial gelatin/tragacanth gum films containing galbanum essential oil for in vitro scratch-healing

Natural substances and bioactive agents possess great potential in wound care based on their ability to promote healing and prevent infection. This study focused on the fabrication of antibacterial wound dressings by combining gelatin (G), tragacanth gum (TG), and galbanum essential oil (GEO) as a loaded drug. TG addition resulted in more elastic and flexible films besides enabling encapsulation of the hydrophobic GEO into the biopolymeric matrix. GEO was utilized as an antibacterial and a wound-healing enhancer for open wounds such as incisions. Field emission scanning electron microscopy (FE-SEM) analysis revealed a porous film structure after GEO incorporation. Higher GEO concentration caused reduced swelling and slower degradation. Water vapor transfer rate varied from 596 to 894 g/m2.day, making the films suitable for wound dressings. GEO release exhibited a two-phase profile with prolonged diffusion-controlled release for a higher content of GEO. The films demonstrated dose-dependent antimicrobial activity against S. aureus and E. coli strains. Effectiveness and noteworthy application of this research were approved by scratch assay on human dermal fibroblast cells, and films with 3 % GEO showed 79.42 % wound closure, which is significantly higher than the control sample (55.15 %), indicating promoted cell migration and promising wound healing properties.

Optimizing alginate dressings with allantoin and chemical modifiers to promote wound healing

Wound healing requires diverse functionalities in dressings, and conventional materials often fall short in water absorption and moisture regulation. Natural sodium alginate is popular in wound dressings due to its excellent film-forming ability, biocompatibility, ionic crosslinking, and pH responsiveness. However, it has limitations in physical stability and solubility in aqueous environments. This study enhanced alginate dressings by incorporating allantoin and treating with calcium chloride and citric acid to improve physicochemical properties and mechanical performance. Treatments for S2 to S5 prevented dissociation and maintained integrity, with suitable water absorption (363 %-442 %) and water vapor transmission rates (612.53-715.39 g × m2 × day-1). The treatments also improved tensile strength (44.90-55.19 MPa). S2 had the highest migration ratio (52.71 %) of L929 cells and wound healing rates for mice skin (86.6 %), indicating that calcium chloride treatment is beneficial. All dressings (S1 to S5) exhibited low cytotoxicity against L929 cells and low hemolysis ratios, indicating good biocompatibility. Higher allantoin content improved wound healing efficacy. This study provides valuable insights for the design and development of alginate dressings in wound repair, expanding allantoin's application in wound healing.

Fabrication of gelatin-based antibacterial bilayer wound dressing using direct writing and electrospinning methods

Fabricating a fibrous well-ordered wound dressing for accelerating full-thickness wounds is a desirable treatment vector. Here, through modifications in the material extrusion device and adding a pneumatic-based injection, a material extrusion method for gelatin was introduced with the ability to fabricate 3D structure with repeat layers to support cell activity for the under layer. Furthermore, in the upper layer, the co-electrospinning of PU with gelatin was designed to simultaneously exploit the oxygen permeability and mechanical stability of PU with regenerative properties and collagen-like structure of gelatin. Moreover, zinc oxide nanoparticles (ZnO) was added into the 3D-printed under layer to synergistically benefit from the antibacterial properties of ZnO and the excellent biocompatibility of gelatin. The controllable porosity of the under layer, enabled through the additive manufacturing method, was adjusted to mimic the extracellular matrix of natural tissue with around (127.28 ± 20.70) μm pore size after swelling with smooth fibers. S. aureus, E. coli, Bacillus subtilis, and Pseudomonas with inhibition zone diameters at ∼ 2.14 cm and ∼ 1.96 cm, ∼ 4.01 cm, and ∼ 2.24 cm, respectively. Moreover, the scaffold showed great biocompatibility toward fibroblast cells after 7 days of cell culture with ∼ 89 % cell viability.

Design, optimization and pharmaceutical characterization of wound healing film dressings with chloramphenicol and ibuprofen

OBJECTIVE

The aim of the present study was to develop and optimize a wound dressing film loaded with chloramphenicol (CAM) and ibuprofen (IBU) using a Quality by Design (QbD) approach.

SIGNIFICANCE

The two drugs have been combined in the same dressing as they address two critical aspects of the wound healing process, namely prevention of bacterial infection and reduction of inflammation and pain related to injury.

METHODS

Three critical formulation variables were identified, namely the ratios of Kollicoat SR 30D, polyethylene glycol 400 and polyvinyl alcohol. These variables were further considered as factors of an experimental design, and 17 formulations loaded with CAM and IBU were prepared via solvent casting. The films were characterized in terms of dimensions, mechanical properties and bioadhesion. Additionally, the optimal formulation was characterized regarding tensile properties, swelling behavior, water vapor transmission rate, surface morphology, thermal behavior, goniometry, in vitro drug release, cell viability, and antibacterial activity.

RESULTS

The film was optimized by setting minimal values for the folding endurance, adhesive force and hardness. The optimally formulated film showed good fluid handling properties in terms of swelling behavior and water vapor transmission rate. IBU and CAM were released from the film up to 80.9% and 82.5% for 8 h. The film was nontoxic, and the antibacterial activity was prominent against Micrococcus spp. and Streptococcus pyogenes.

CONCLUSIONS

The QbD approach was successfully implemented to develop and optimize a novel film dressing promising for the treatment of low-exuding acute wounds prone to infection and inflammation.

Chitosan and neem gum-based polyelectrolyte complex for design of allantoin loaded biocomposite film: In-vitro, ex-vivo, and in-vivo characterization

Presently, the preference for chitosan (CS) and gum polysaccharides in biomedical applications including drug delivery and wound healing has been extensively documented. Despite this, the demerits of CS and gum polysaccharides such as poor mechanical properties, degradation rate, swelling, etc., limit their applications for designing biocomposite films for drug delivery. Therefore, the anticipated work aims to design a CS and neem gum polysaccharides (NGP) polyelectrolyte complex-based allantoin (AT)-loaded (CS/NGP-AT) biocomposite film for improved wound healing. In brief, CS, NGP, and CS/NGP-AT-based biocomposite films were prepared using the solvent-casting method, and in-vitro, ex-vivo, and in-vivo characterizations were performed to assess the performance of these biocomposite films compared to their counterparts. In this, diffractogram and thermogram analysis assured the conversion of crystalline AT into an amorphous form. The optimized CS/NGP/AT-3 formulation exhibited controlled water absorption, appropriate water uptake capacity, good water retention ability, excellent water vapor transmission rate, controlled degradation rate, enhanced mechanical properties, cell and blood biocompatibility, etc. Furthermore, it offered improved antimicrobial, anti-inflammatory, and antioxidant potential. The optimized film provided a modified release (88.3 ± 0.3 %) of AT from the film for up to 48 h. Wound healing experiments on rats and their histopathology studies confirmed a significantly higher rate of wound recovery within 14 days compared to the control and CS/NGP film, attributable to the combined effects of CS, NGP, and AT. In conclusion, the fabricated CS/NGP-based biocomposite film presents promising prospects as an excellent candidate for wound healing applications.

Catecholamines polymerization crosslinking for alginate-based burn wound dressings developed with ciprofloxacin and zinc oxide interactions

There is an increasing demand for stable and durable wound dressings to treat burn injuries and infections. Bioactive electrospun nanofibrous mats with antibacterial properties are promising for wound dressing usage. Electrospinning of biopolymers for wound dressing applications needs post-spinning crosslinking to prevent mat dissolution in moist wound environments. Here, we prepared durable wound dressing by using the Dopamine (DA) polymerization crosslinking in Alginate (ALG)/Polyvinyl alcohol (PVA) nanofibrous mats, which are developed by Ciprofloxacin (CIP) and Zinc oxide (ZO). The nanofibrous mats were investigated by FESEM, FTIR, mechanical strength, water contact angle, degradation, degree of swelling, and WVTR tests. The analyses demonstrate the nanofibrous mats with uniform and unbranched fibers, with a hydrophilic nature, which was porous, durable, and stable. Also, it showed the CIP and ZO addition enhanced their durability by crosslinking reinforcement. In addition, the drug release and antibacterial assays demonstrated the pH-sensitive release with more drug release at higher pH (bacterial invasion) and impressive antibacterial activity (up to 99 %). In the burn wound model in rats, the ALG/PVA/DA/CIP/ZO nanofibrous mats displayed excellent wound healing ability in wound closure and tissue regeneration. Also, complete re-epithelization and remodeling and highest collagen synthesis in histological assessment.

Nanoemulsion-integrated gelatin/bacterial cellulose nanofibril-based multifunctional film: Fabrication, characterization, and application

The current requirements of food safety regulations and the environmental impact stemming from plastic packaging can only be addressed by developing suitable bio-nanocomposite films. Therefore, this study is dedicated to the fabrication of multifunctional film composed of gelatin, bacterial cellulose nanofibrils (BCNF), and black pepper essential oil nanoemulsion (BPEONE) and application for duck meat preservation. BCNF was prepared through ultrasonication of cellulose derived from Komagataeibacter xylinus. BPEONE observed spherical morphology with a diameter ranging from 83.7 to 118 nm. A film matrix containing a higher gelatin proportion than BCNF was more effective in trapping BPEONE. However, increasing the BPEONE fraction showed more surface abrasion and voids in the film morphology. A flexible film with good interaction, crystallinity, and greater thermal stability (421 °C) was developed. Nevertheless, film hydrophobicity (118.89°) declined, resulting in a notable effect on water solubility, swelling, and water vapor permeability. Moreover, the film had improved antibacterial and antioxidant activities, coupled with controlled release characteristics. Consequently, the developed film effectively retarded the lipid oxidation, inhibited microbial growth, and extended the shelf life of duck meat at refrigeration (4 °C) by 3 days, and made the film a promising alternative in the realm of bio-active packaging technology.

Oleogels for the Promotion of Healthy Skin Care Products: Synthesis and Characterization of Allantoin Containing Moringa-based Oleogel

BACKGROUND

Oleogelation is an efficient and emerging approach for obtaining biocompatible and biodegradable elastic semisolid crystals to be used in various cosmetic and pharmaceutical formulations. Recently, drug incorporation in oil structuring has been a promising strategy under consideration due to the effectiveness of this method. Plant oils have very beneficial characteristics for skin care and wound healing due to the presence of certain antioxidants.

METHODS

In this study, the oleogels of Moringa oleifera seed oil with natural polysaccharides, including pectin, chitosan, and xanthan gum, were prepared using the emulsion template method. Moringa oil was selected because it can hydrate and moisturize the skin and has great antioxidant activity. Also, the natural polysaccharides, i.e., pectin and chitosan, exhibited good gelling properties. Allantoin, which is a wound healer and eucalyptus leaf oil with antioxidant potential, was incorporated into the emulsion-based-oleogels to enhance the antioxidant and antimicrobial activity of the oleogels.

RESULTS

Allantoin and eucalyptus-loaded oleogels exhibited good antibacterial activity against E. coli. The FTIR spectra of moringa-based oleogels in the range between 3226-3422 cm-1 indicate the presence of hydrogen bonding in oleogels.

CONCLUSION

The antioxidant potential of allantoin and eucalyptus-containing oleogel was maximized, and an IC50 value of 0.9719 μM was found. Maximum release of allantoin from oleogel was observed in the first hour.

A novel multifunctional chitosan-gelatin/carboxymethyl cellulose-alginate bilayer hydrogel containing human placenta extract for accelerating full-thickness wound healing

The replication of skin's dermal and epidermal morphology within a full-thickness wound using a bi-layer hydrogel to cater to their distinct needs is a compelling pursuit. Moreover, human placenta extract (HPE), containing a diverse array of bioactive agents, has proven to be effective in promoting the wound healing process and enhancing epidermal keratinocytes. This study presents a multifunctional bi-layer hydrogel incorporating HPE for accelerating full-thickness wound healing through sustained HPE release, inhibition of bacteria invasion, and promotion of cell proliferation. The upper layer of the scaffold, known as the dressing layer, is composed of carboxymethyl cellulose and sodium alginate, serving as a supportive layer for cell proliferation. The under layer, referred to as the regenerative layer, is composed of chitosan and gelatin, providing an extracellular matrix-like, porous, moist, and antibacterial environment for cell growth. The scaffold was optimized to replicate the morphology of the dermal and epidermal layers, with suitable fibroblast infiltration and a pore size of approximately 283μm. Furthermore, the degradation rate of the samples matched the wound healing rate and persisted throughout this period. The sustained HPE release rate, facilitated by the degradation rate, was optimized to reach ~98% after 28 days, covering the entire healing period. The samples demonstrated robust antibacterial capabilities, with bacterial inhibition zone diameters of and 2.63±0.12cm for S. aureus and E. coli, respectively. The biocompatibility of the samples remained at approximately 68.33±4.5% after 21 days of fibroblast cell culture. The in vivo experiment indicated that the HPE@Bilayer hydrogel promotes the formation of new blood vessels and fibroblasts during the early stages of healing, leading to the appropriate formation of granulation tissue and a wound contraction rate of (79.31±3.1)%. Additionally, it resulted in the formation of a thick epidermal layer (keratinization) that effectively covered all the impaired areas, achieving a wound contraction rate of 95.83±6.3% at the late stage of wound healing. Furthermore, immunohistochemistry staining for CD31 and TGF-β revealed that the HPE@Bilayer group had 22 blood vessels/field and 34%-66% immunoactive cells, respectively, after 14 days of healing. However, by day 21, angiogenesis and TGF-β expression had declined, demonstrating that the wounds had been successfully treated with minimal scarring.

Fabrication and characterization of new levan@CBD biocomposite sponges as potential materials in natural, non-toxic wound dressing applications

Wound healing is a complex process; therefore, new dressings are frequently required to facilitate it. In this study, porous bacterial levan-based sponges containing cannabis oil (Lev@CBDs) were prepared and fully characterized. The sponges exhibited a suitable swelling ratio, proper water vapor transmission rate, sufficient thermal stability, desired mechanical properties, and good antioxidant and anti-inflammatory properties. The obtained Lev@CBD materials were evaluated in terms of their interaction with proteins, human serum albumin and fibrinogen, of which fibrinogen revealed the highest binding effect. Moreover, the obtained biomaterials exhibited antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, as well as being non-hemolytic material as indicated by hemolysis tests. Furthermore, the sponges were non-toxic and compatible with L929 mouse fibroblasts and HDF cells. Most significantly, the levan sponge with the highest content of cannabis oil, in comparison to others, retained its non-hemolytic, anti-inflammatory, and antimicrobial properties after prolonged storage in a climate chamber at a constant temperature and relative humidity. The designed sponges have conclusively proven their beneficial physicochemical properties and, at the preliminary stage, biocompatibility as well, and therefore can be considered a promising material for wound dressings in future in vivo applications.

Fabrication and characterization of an antibacterial chitosan-coated allantoin-loaded NaCMC/SA skin scaffold for wound healing applications

The field of tissue engineering has recently emerged as one of the most promising approaches to address the limitations of conventional tissue replacements for severe injuries. This study introduces a chitosan-coated porous skin scaffold based on sodium carboxymethyl cellulose (NaCMC) and sodium alginate (SA) hydrogels, incorporating allantoin (AL) as an antibacterial agent. The NaCMC/SA hydrogel was cross-linked with epichlorohydrin (ECH) and freeze-dried to obtain a three-dimensional porous structure. The coated and non-coated scaffolds underwent comprehensive evaluation and characterization through various in-vitro analyses, including SEM imaging, swelling, degradation, and mechanical assessments. Furthermore, the scaffolds were studied regarding their allantoin (AL) release profiles, antibacterial properties, cell viability, and cell adhesion. The in-vitro analyses revealed that adding a chitosan (CS) coating and allantoin (AL) to the NaCMC/SA hydrogel significantly improved the scaffolds' antibacterial properties and cell viability. It was observed that the NaCMC:SA ratio and ECH concentration influenced the swelling capacity, biodegradation, drug release profile, and mechanical properties of the scaffolds. Samples with higher NaCMC content exhibited enhanced swelling capacity, more controlled allantoin (AL) release, and improved mechanical strength. Furthermore, the in-vivo results demonstrated that the proposed skin scaffold exhibited satisfactory biocompatibility and supported cell viability during wound healing in Wistar rats, highlighting its potential for clinical applications.

Development of biomaterials based on chitosan-gelatin nanofibers encapsulated with Ziziphora clinopodioides essential oil and Heracleum persicum extract for extending the shelf-life of vacuum-cooked beef sausages

The aims of the current study were to encapsulate Ziziphora clinopodioides essential oil (ZEO, 0%, 0.15%, and 0.25%) and Heracleum persicum extract (HPE, 0%, 0.25%, and 0.5%) into the chitosan-gelatin (CH-GE) nanofibers through the electrospinning process to improve the shelf-life of vacuum-cooked beef sausages through 70 days of refrigerated storage. Scanning electron microscopy indicated that all nanofibers appeared thin, well-defined, smooth, and possessed uniform thread-like fibers without any beads or nodule formations. The Fourier transform infrared spectroscopy study confirmed the molecular interaction between encapsulated compounds and CH-GE nanofibers. The X-ray diffraction analysis of nanofibers showed an increase in crystallinity after incorporating ZEO and HPE into the polymer. Treated sausages with CH-GE-ZEO 0.25%-HPE 0.25% and CH-GE-ZEO 0.25%-HPE 0.5% showed significantly lower microbial population and lipid oxidation than the control group during the experiment period (P < 0.05). Sausages formulated with designated CH-GE nanofibers had better microbial, chemical, and sensory properties compared to sausages treated with pure ZEO/HPE during refrigerated storage. The findings also showed that treated sausages with CH-GE-ZEO 0.25%-HPE 0.5% had the highest color, odor, texture, and overall acceptability after 70 days of refrigerated storage conditions. Therefore, this treatment could be applicable for the prolonged storage conditions during cooked beef sausage production.

A self-healable and bioadhesive acacia gum polysaccharide-based injectable hydrogel for wound healing acceleration

The present study aimed at developing an injectable hydrogel based on acacia gum (AG) for wound healing acceleration. The hydrogels were synthetized through metal-ligand coordination mediated by Fe3+ and characterized in terms of gelation time, gel content, initial water content, swelling capacity, water retention ratio, and porosity. Moreover, FTIR, XRD and TGA analyses were performed for the hydrogels and allantoin (Alla) loaded ones. Furthermore, bioadhessiveness, and self-healing as well as antibacterial, toxicity and wound healing potentials of the hydrogels were evaluated. The hydrogels displayed fast gelation time, high swelling, porosity, and bioadhessiveness, as well as antioxidant, self-healing, antibacterial, blood clotting, and injectability properties. FTIR, XRD and TGA analyses confirmed hydrogel synthesis and drug loading. The Alla-loaded hydrogels accelerated wound healing by decreasing the inflammation and increasing the cell proliferation as well as collagen deposition. Hemocompatibility, cell cytotoxicity, and in vivo toxicity experiments were indicative of a high biocompatibility level for the hydrogels. Given the advantages of fast gelation, injectability and beneficial biological properties, the use of Alla-loaded hydrogels could be considered a new remedy for efficient wound healing.

Development of Ag NPs/allantoin loaded PCL/GEL electrospun nanofibers for topical wound treatment

In the present study, the allantoin and silver nanoparticle (Ag NPs) loaded poly caprolactone/gelatin (PCL/GEL) nanofibers produced using electrospinning technique and their cyto-compatibility and wound healing activity were evaluated in vitro and in vivo. The SEM imaging revealed diameters of 278.8 ± 10 and 240.6 ± 12 nm for PCL/GEL/Ag NPs and PCL/GEL/Ag NPs/allantoin scaffolds. The Ag NPs entrapment into scaffolds was evaluated by FTIR analysis and EDX mapping. Both scaffolds containing Ag NPs and Ag NPs/allantoin exhibited valuable wound healing activity in Wistar rat animal model. The profound granulation tissue formation, high collagen deposition in coordination with low level of edema and inflammatory cells in Ag NPs/allantoin loaded scaffolds resulted in complete and mature re-epithelialization in giving the healing score (12 out of 12) equal to positive control group to the wounds treated with these scaffolds. It was concluded that the Ag NPs/allantoin loaded scaffolds regarding to their good antibacterial activity and excellent wound healing activity could be introduced as new effective wound dressing materials.

Cell electrospinning and its application in wound healing: principles, techniques and prospects

Currently, clinical strategies for the treatment of wounds are limited, especially in terms of achieving rapid wound healing. In recent years, based on the technique of electrospinning (ES), cell electrospinning (C-ES) has been developed to better repair related tissues or organs (such as skin, fat and muscle) by encapsulating living cells in a microfiber or nanofiber environment and constructing 3D living fiber scaffolds. Therefore, C-ES has promising prospects for promoting wound healing. In this article, C-ES technology and its advantages, the differences between C-ES and traditional ES, the parameters suitable for maintaining cytoactivity, and material selection and design issues are summarized. In addition, we review the application of C-ES in the fields of biomaterials and cells. Finally, the limitations and improved methods of C-ES are discussed. In conclusion, the potential advantages, limitations and prospects of C-ES application in wound healing are presented.

Chitosan-Glycolic Acid Gel Modification of Chloride Ion Transport in Mammalian Skin: An In Vitro Study

Chitosan, a polyaminosaccharide with high medical and cosmetic potential, can be combined with the beneficial properties of glycolic acid to form a gel that not only moisturizes the skin, but also has a regenerative effect. Its involvement in the activation of biochemical processes may be associated with the activity of skin ion channels. Therefore, the aim of the research was to evaluate the immediate (15 s) and long-term (24 h) effect of chitosan-glycolic acid gel (CGG) on the transepithelial electric potential and the transepithelial electric resistance (R) of skin specimens tested in vitro. Stimulation during immediate and prolonged application of CGG to skin specimens resulted in a significant decrease in the measured minimal transepithelial electric potential (PDmin). The absence of any change in the R after the CGG application indicates that it does not affect the skin transmission, or cause distortion, microdamage or changes in ion permeability. However, the reduction in potential may be due to the increased transport of chloride ions, and thus water, from outside the cell into the cell interior. Increased secretion of chloride ions is achieved by stimulating the action of the CFTR (cystic fibrosis transmembrane conductance). It can be assumed that chitosan gently stimulates the secretion of chlorides, while maintaining a tendency to reduce the transport of sodium ions, without causing deformation or tissue damage.

Cysteine Enrichment Mediates Co-Option of Uricase in Reptilian Skin and Transition to Uricotelism

Uric acid is the main means of nitrogen excretion in uricotelic vertebrates (birds and reptiles) and the end product of purine catabolism in humans and a few other mammals. While uricase is inactivated in mammals unable to degrade urate, the presence of orthologous genes without inactivating mutations in avian and reptilian genomes is unexplained. Here we show that the Gallus gallus gene we name cysteine-rich urate oxidase (CRUOX) encodes a functional protein representing a unique case of cysteine enrichment in the evolution of vertebrate orthologous genes. CRUOX retains the ability to catalyze urate oxidation to hydrogen peroxide and 5-hydroxyisourate (HIU), albeit with a 100-fold reduced efficiency. However, differently from all uricases hitherto characterized, it can also facilitate urate regeneration from HIU, a catalytic property that we propose depends on its enrichment in cysteine residues. X-ray structural analysis highlights differences in the active site compared to known orthologs and suggests a mechanism for cysteine-mediated self-aggregation under H2O2-oxidative conditions. Cysteine enrichment was concurrent with the transition to uricotelism and a shift in gene expression from the liver to the skin where CRUOX is co-expressed with β-keratins. Therefore, the loss of urate degradation in amniotes has followed opposite evolutionary trajectories: while uricase has been eliminated by pseudogenization in some mammals, it has been repurposed as a redox-sensitive enzyme in the reptilian skin.

Characterization and In Vivo Assay of Allantoin-Enriched Pectin Hydrogel for the Treatment of Skin Wounds

This work describes a liquid allantoin-enriched pectin hydrogel with hydrophilic behavior that is supported by the presence of functional groups related to healing efficacy. A topical study shows the effect of the hydrogel application on surgically induced skin wound healing in a rat model. Contact angle measurements confirm hydrophilic behavior (11.37°), while Fourier-transform infrared spectroscopy indicates the presence of functional groups related to the healing effectiveness (carboxylic acid and amine groups). Allantoin is distributed on the surface and inside the amorphous pectin hydrogel surrounded by a heterogeneous distribution of pores. This promotes wound drying with better interaction between the hydrogel and cells involved in the wound healing process. An experimental study with female Wistar rats indicates that the hydrogel improves wound contraction, reducing around 71.43% of the total healing time and reaching total wound closure in 15 days.

Curcumin-Loaded Bioactive Polymer Composite Film of PVA/Gelatin/Tannic Acid Downregulates the Pro-inflammatory Cytokines to Expedite Healing of Full-Thickness Wounds

Curcumin (Cur) entrapped poly(vinyl alcohol) (PVA)/gelatin composite films were prepared by cross-linking with tannic acid (TA) as bioactive dressings for rapid wound closure. Films were evaluated for mechanical strength, swelling index, water vapor transmission rate (WVTR), film solubility, and in-vitro drug release studies. SEM revealed uniform and smooth surfaces of blank (PG9) and Cur-loaded composite films (PGC4). PGC4 exhibited excellent mechanical strength (tensile strength (TS) and Young's modulus (YM) were 32.83 and 0.55 MPa, respectively), swelling ability (600-800% at pH 5.4, 7.4, and 9), WVTR (2003 ± 26), and film solubility (27.06 ± 2.0). Sustained release (81%) of the encapsulated payload was also observed for 72 h. The antioxidant activity determined by DPPH free radical scavenging showed that the PGC4 possessed strong % inhibition. The PGC4 formulation displayed higher antibacterial potential against S. aureus (14.55 mm zone of inhibition) and E. coli (13.00 mm zone of inhibition) compared to blank and positive control by the agar well diffusion method. An in-vivo wound healing study was carried out on rats using a full-thickness excisional wound model. Wounds treated with PGC4 showed very rapid healing about 93% in just 10 days post wounding as compared to 82.75% by Cur cream and 80.90% by PG9. Furthermore, histopathological studies showed ordered collagen deposition and angiogenesis along with fibroblast formation. PGC4 also exerted a strong anti-inflammatory effect by downregulating the expression of pro-inflammatory cytokines (TNF-α and IL-6 were lowered by 76% and 68% as compared to the untreated group, respectively). Therefore, Cur-loaded composite films can be an ideal delivery system for effective wound healing.

Chitosan/Gelatin Scaffolds Loaded with Jatropha mollissima Extract as Potential Skin Tissue Engineering Materials

This work aimed to develop chitosan/gelatin scaffolds loaded with ethanolic extract of Jatropha mollissima (EEJM) to evaluate the influence of its content on the properties of these structures. The scaffolds were prepared by freeze-drying, with different EEJM contents (0-10% (w/w)) and crosslinked with genipin (0.5% (w/w)). The EEJM were characterized through High Performance Liquid Chromatography coupled to a Diode Array Detector (HPLC-DAD), and the determination of three secondary metabolites contents was accomplished. The physical, chemical and biological properties of the scaffolds were investigated. From the HPLC-DAD, six main substances were evidenced, and from the quantification of the total concentration, the condensed tannins were the highest (431.68 ± 33.43 mg·g^-1). Spectroscopy showed good mixing between the scaffolds' components. Adding and increasing the EEJM content did not significantly influence the properties of swelling and porosity, but did affect the biodegradation and average pore size. The enzymatic biodegradation test showed a maximum weight loss of 42.89 within 28 days and reinforced the efficiency of genipin in crosslinking chitosan-based materials. The addition of the extract promoted the average pore sizes at a range of 138.44-227.67 µm, which is compatible with those reported for skin regeneration. All of the scaffolds proved to be biocompatible for L929 cells, supporting their potential application as skin tissue engineering materials.

Basella alba stem extract integrated poly (vinyl alcohol)/chitosan composite films: A promising bio-material for wound healing

Natural extract-based bio-composite material for wound healing is gaining much attention due to risk of infection and high cost of commercial wound dressing film causes serious problem on the human well-being. Herein, the study outlines the preparation of Poly (vinyl alcohol)/Chitosan/Basella alba stem extract (BAE) based bio-composite film through solvent casting technique and well characterized for wound healing application. Incorporation of BAE into Poly (vinyl alcohol)/Chitosan matrix has shown existence of secondary interactions confirmed by FT-IR analysis. Good morphology, thermal stability and significant improvement in flexibility (∼63.38 %) of the films were confirmed by SEM, TGA and Mechanical test results, respectively. Hydrophilic property (∼9.04 %), water vapor transmission rate (∼70.07 %), swelling ability (∼14.7 %) and degradation rate (∼14.04 %) were enhanced with increase in BAE content. In-vitro studies have shown good antibacterial activity against foremost infectious bacterial strains S. aureus and E. coli. Additionally, BAE integrated Poly (vinyl alcohol)/Chitosan film has amplified anti-inflammatory (∼79.38 %) property, hemocompatibility and excellent biocompatibility (94.9 %) was displayed by cytotoxicity results. Moreover, in-vitro scratch assay and cell adhesion test results illustrated prominent wound healing (96.5 %) and adhesion. Overall results of the present work proclaim that developed bio-composite film could be utilized as a biomaterial in wound care applications.

Fabrication of chitosan-gelatin films incorporated with thymol-loaded alginate microparticles for controlled drug delivery, antibacterial activity and wound healing: In-vitro and in-vivo studies

Previously, studies have demonstrated the unique characteristics of chitosan-gelatin films as wound dressings applications. However, their application has been limited due to their inadequacy of antimicrobial and anti-inflammatory characteristics. To improve the intended multifunctional characteristics of chitosan-gelatin film, in this study, we designed a novel composite film with the capability of controlled and prolonged release of thymol as a natural antioxidant and antimicrobial drug. Here, thymol-loaded ALG MPs (Thymol-ALG MPs) were prepared by electrospraying method and incorporated into the chitosan-gelatin film. The composite wound dressings of Thymol-ALG MPs incorporated in chitosan-gelatin film (CS-GEL/Thymol-ALG MPs) were characterized by in vitro and in vivo evaluations. The Thymol-ALG MPs demonstrated spherical and uniform morphology, with high encapsulation efficiency (88.9 ± 1.1 %). The CS-GEL/Thymol-ALG MPs exhibited high antibacterial activity against both Gram-positive and Gram-negative bacteria and no cytotoxicity for the L929 fibroblast cells. The release trend of thymol from CS-GEL/Thymol-ALG MPs and Thymol-ALG MPs followed a pseudo-Fickian diffusion mechanism. This wound dressing effectively accelerates the wound healing process at rats' full-thickness skin excisions. Also, the histological analysis demonstrated that the CS-GEL/Thymol-ALG MPs could significantly enhance epithelialization, collagen deposition, and induce skin regeneration. The present antibacterial composite film has promising characteristics for wound dressings applications.

Gallic Acid-Loaded Sodium Alginate-Based (Polyvinyl Alcohol-Co-Acrylic Acid) Hydrogel Membranes for Cutaneous Wound Healing: Synthesis and Characterization

Traditional wound dressings often cannot treat wounds caused by bacterial infections or other wound types that are insensitive to these wound treatments. Therefore, a biodegradable, bioactive hydrogel wound dressing could be an effective alternative option. The purpose of this study was to develop a hydrogel membrane comprised of sodium alginate, polyvinyl alcohol, acrylic acid, and gallic acid for treating skin wounds. The newly developed membranes were analyzed using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), sol-gel fraction, porosity, mechanical strength, swelling, drug release and data modelling, polymeric network parameters, biodegradation, and antioxidation (DPPH and ABTS) and antimicrobial activity against Gram-positive and negative bacteria. The results revealed that hydrogel membranes were crosslinked successfully and had excellent thermal stability, high drug loading, greater mechanical strength, and exhibited excellent biodegradation. Additionally, the swelling ability and the porosity of the surface facilitated a controlled release of the encapsulated drug (gallic acid), with 70.34% release observed at pH 1.2, 70.10% at pH 5.5 (normal skin pH), and 86.24% at pH 7.4 (wounds pH) in 48 h. The gallic acid-loaded hydrogel membranes showed a greater area of inhibition against Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli bacteria as well as demonstrated excellent antioxidant properties. Based on Franz cell analyses, the permeation flux of the drug from optimized formulations through mice skin was 92 (pH 5.5) and 110 (pH 7.4) μg/cm²·h^-1. Moreover, hydrogel membranes retained significant amounts of drug in the skin for 24 h, such as 2371 (pH 5.5) and 3300 µg/cm² (pH 7.4). Acute dermal irritation tests in rats showed that hydrogel membranes were nonirritating. Hydrogel membranes containing gallic acid could be an effective option for improving wound healing and could result in faster wound healing.

Investigation of wound healing efficiency of multifunctional eudragit/soy protein isolate electrospun nanofiber incorporated with ZnO loaded halloysite nanotubes and allantoin

One significant aspect of the current therapeutic agents employed in wound healing involves the engineering of nano polymeric scaffolds to mimic the properties of extracellular matrix (ECM). The present work aimed to prepare and evaluate Eudragit® L100 (EU) nanofibers in combination with soy protein isolate (SPI). Allantoin (Ala) with a 2 wt% was encapsulated as a model drug renowned for its anti-inflammatory and antioxidant agents. Moreover, the synthesized ZnO-halloysite nanotubes (ZHNTs) with different concentrations of 1, 3, and 5 wt% were incorporated into the EU/SPI/Ala nanofiber as a reinforcing filler and a remarkable antibacterial agent. The scanning electron microscope (SEM) analysis showed that by increasing the weight percentage of SPI from 1 % to 2.5 %, the average diameter of nanofibers decreased from 132.3 ± 51.3 nm to 126.7 ± 47.2 nm. It was 223.5 ± 95.6 nm for nanofibers containing 5 wt% ZHNTs (the optimal sample). The evaluation of in vitro release kinetics of Ala for 24 h, showed a burst release during the first 2 h and a sustained release during the subsequent times. Moreover, the structure, crystallinity, and thermal stability of synthesized nanofibers were characterized by Fourier Transform Infrared Spectrometry (FTIR), X-ray diffraction (XRD), and Thermo gravimetric analysis (TGA), respectively. In vitro degradation and mechanical characteristics of these nanofibers were studied. Furthermore, the capability of the nanofibers for cell proliferation was revealed through the MTT test and field emission scanning electron microscopy (FESEM) images of cell attachment. The antimicrobial activity of EU/SPI/Ala/ZHNTs showed that this sample with high ZHNTs content (5 w%t) had the most remarkable antibacterial activity against S. aureus. The results revealed that EU/SPI/Ala/ZHNTs mats could be promising potential wound dressings.

Melt electrowriting of PLA, PCL, and composite PLA/PCL scaffolds for tissue engineering application

Fabrication of well-ordered and bio-mimetic scaffolds is one of the most important research lines in tissue engineering. Different techniques have been utilized to achieve this goal, however, each method has its own disadvantages. Recently, melt electrowriting (MEW) as a technique for fabrication of well-organized scaffolds has attracted the researchers' attention due to simultaneous use of principles of additive manufacturing and electrohydrodynamic phenomena. In previous research studies, polycaprolactone (PCL) has been mostly used in MEW process. PCL is a biocompatible polymer with characteristics that make it easy to fabricate well-arranged structures using MEW device. However, the mechanical properties of PCL are not favorable for applications like bone tissue engineering. Furthermore, it is of vital importance to demonstrate the capability of MEW technique for processing a broad range of polymers. To address aforementioned problems, in this study, three ten-layered box-structured well-ordered scaffolds, including neat PLA, neat PCL, and PLA/PCL composite are fabricated using an MEW device. Printing of the composite PLA/PCL scaffold using the MEW device is conducted in this study for the first time. The MEW device used in this study is a commercial fused deposition modeling (FDM) 3D printer which with some changes in its setup and configuration becomes prepared for being used as an MEW device. Since in most of previous studies, a setup has been designed and built for MEW process, the use of the FDM device can be considered as one of the novelties of this research. The printing parameters are adjusted in a way that scaffolds with nearly equal pore sizes in the range of 140 µm to 150 µm are fabricated. However, PCL fibers are mostly narrower (diameters in the range of 5 µm to 15 µm) than PLA fibers with diameters between 15 and 25 µm. Unlike the MEW process of PCL, accurate positioning of PLA fibers is difficult which can be due to higher viscosity of PLA melt compared to PCL melt. The printed composite PLA/PCL scaffold possesses a well-ordered box structure with improved mechanical properties and cell-scaffold interactions compared to both neat PLA and PCL scaffolds. Besides, the composite scaffold exhibits a higher swelling ratio than the neat PCL scaffold which can be related to the presence of less hydrophobic PLA fibers. This scaffold demonstrates an anisotropic behavior during uniaxial tensile test in which its Young's modulus, ultimate tensile stress, and strain to failure all depend on the direction of the applied tensile force. This anisotropy makes the composite PLA/PCL scaffold an exciting candidate for applications in heart tissue engineering. The results of in-vitro cell viability test using L929 mouse murine fibroblast and human umbilical vein endothelial (HUVEC) cells demonstrate that all of the printed scaffolds are biocompatible. In particular, the composite scaffold presents the highest cell viability value among the fabricated scaffolds. All in all, the composite PLA/PCL scaffold shows that it can be a promising substitution for neat PCL scaffold used in previous MEW studies.

Histological Evaluation of Cassava Starch/Chicken Gelatin Membranes

The use of biopolymers for tissue engineering has recently gained attention due to the need for safer and highly compatible materials. Starch is one of the most used biopolymers for membrane preparation. However, incorporating other polymers into starch membranes introduces improvements, such as better thermal and mechanical resistance and increased water affinity, as we reported in our previous work. There are few reports in the literature on the biocompatibility of starch/chicken gelatin composites. We assessed the in vivo biocompatibility of the five composites (T1–T5) cassava starch/gelatin membranes with subdermal implantations in biomodels at 30, 60, and 90 days. The FT-IR spectroscopy analysis demonstrated the main functional groups for starch and chicken gelatin. At the same time, the thermal study exhibited an increase in thermal resistance for T3 and T4, with a remaining mass (~15 wt.%) at 800 °C. The microstructure analysis for the T2–T4 demonstrated evident roughness changes with porosity presence due to starch and gelatin mixture. The decrease in the starch content in the composites also decreased the gelatinization heats for T3 and T4 (195.67, 196.40 J/g, respectively). Finally, the implantation results demonstrated that the formulations exhibited differences in the degradation and resorption capacities according to the starch content, which is easily degraded by amylases. However, the histological results showed that the samples demonstrated almost complete reabsorption without a severe immune response, indicating a high in vivo biocompatibility. These results show that the cassava starch/chicken gelatin composites are promising membrane materials for tissue engineering applications.

Chitosan-Gelatin Films Cross-Linked with Dialdehyde Cellulose Nanocrystals as Potential Materials for Wound Dressings

In this study, thin chitosan-gelatin biofilms cross-linked with dialdehyde cellulose nanocrystals for dressing materials were received. Two types of dialdehyde cellulose nanocrystals from fiber (DNCL) and microcrystalline cellulose (DAMC) were obtained by periodate oxidation. An ATR-FTIR analysis confirmed the selective oxidation of cellulose nanocrystals with the creation of a carbonyl group at 1724 cm-1. A higher degree of cross-linking was obtained in chitosan-gelatin biofilms with DNCL than with DAMC. An increasing amount of added cross-linkers resulted in a decrease in the apparent density value. The chitosan-gelatin biofilms cross-linked with DNCL exhibited a higher value of roughness parameters and antioxidant activity compared with materials cross-linked with DAMC. The cross-linking process improved the oxygen permeability and anti-inflammatory properties of both measurement series. Two samples cross-linked with DNCL achieved an ideal water vapor transition rate for wound dressings, CS-Gel with 10% and 15% addition of DNCL-8.60 and 9.60 mg/cm2/h, respectively. The swelling ability and interaction with human serum albumin (HSA) were improved for biofilms cross-linked with DAMC and DNCL. Significantly, the films cross-linked with DAMC were characterized by lower toxicity. These results confirmed that chitosan-gelatin biofilms cross-linked with DNCL and DAMC had improved properties for possible use in wound dressings.

NiII NPs entrapped within a matrix of l-glutamic acid cross-linked chitosan supported on magnetic carboxylic acid-functionalized multi-walled carbon nanotube: a new and efficient multi-task catalytic system for the green one-pot synthesis of diverse heterocyclic frameworks

In the present study, a new l-glutamic acid cross-linked chitosan supported on magnetic carboxylic acid-functionalized multi-walled carbon nanotube (Fe3O4/f-MWCNT-CS-Glu) nanocomposite was prepared through a convenient one-pot multi-component sequential strategy. Then, nickelII nanoparticles (NiII NPs) were entrapped within a matrix of the mentioned nanocomposite. Afterward, the structure of the as-prepared Fe3O4/f-MWCNT-CS-Glu/NiII nanosystem was elucidated by various techniques, including FT-IR, PXRD, SEM, TEM, SEM-based EDX and elemental mapping, ICP-OES, TGA/DTA, and VSM. In the next part of this research, the catalytic applications of the mentioned nickelII-containing magnetic nanocomposite were assessed upon green one-pot synthesis of diverse heterocyclic frameworks, including bis-coumarins (3a-n), 2-aryl(or heteroaryl)-2,3-dihydroquinazolin-4(1H)-ones (5a-r), 9-aryl-3,3,6,6-tetramethyl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-diones (7a-n), and 2-amino-4-aryl-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitriles (9a-n). The good-to-excellent yields of the desired products, satisfactory reaction rates, use of water solvent or solvent-free reaction medium, acceptable turnover numbers (TONs) and turnover frequencies (TOFs), along with comfortable recoverability and satisfying reusability of the as-prepared nanocatalyst for at least eight successive runs, and also easy work-up and purification procedures are some of the advantages of the current synthetic protocols.

Allantoin-functionalized silk fibroin/sodium alginate transparent scaffold for cutaneous wound healing

In clinical application, it's highly desirable for developing bio-functionalized cutaneous scaffold with transparent features for convenient observation, excellent biocompatibility, and high efficiency for promoting wound repair. Herein, allantoin-functionalized composite hydrogel was developed by coupling silk fibroin (SF) and sodium alginate (SA) for treatment of cutaneous wounds. The prepared allantoin-functionalized SF-SA composite scaffolds (AFAS) exhibited excellent mechanical properties, especially featured by similar ultimate tensile strength (UTS) and elongation at breaking to human skin. Besides, the solvent-casting method guaranteed the AFAS to obtain highly transparent properties with sufficient moisture permeability and excellent adhesion in wet state. In vitro cellular experiments demonstrated excellent biocompatibility of the scaffold that attachment and proliferation of NIH-3T3 fibroblast cells was promoted in the presence of AFAS. Furthermore, the scaffolds exhibited efficient hemostatic property, based on rat hepatic hemorrhage model. In a cutaneous excisional mouse wound model, the AFAS significantly improved the wound closure rate, compared with pure SF-SA scaffolds and blank control. Moreover, the histomorphological assessments showed that AFAS facilitated the integrity of skin and wound healing process by enhancing collagen deposition, re-epithelialization and vascularization at wound site. The results demonstrate that the novel allantoin-functionalized SF/SA transparent hydrogel has great potential for clinical treatment of cutaneous wound.

Arabinoxylan-Carboxymethylcellulose Composite Films for Antibiotic Delivery to Infected Wounds

Modern dressings should provide for local delivery of antibiotics and protect the wound from bacterial infection, dehydration and environmental factors to achieve optimal healing. The local delivery of antibiotics can reduce adverse effects and resistance challenges. In this study, we fabricated film dressings composed of arabinoxylan (AX) from Plantago ovata seed husks and carboxymethylcellulose (CMC) by a solvent cast method for the delivery of the antibiotic amikacin (AMK). To determine the suitability of the prepared AX-CMC composite films as wound dressings and drug delivery materials, their physical, chemical, mechanical, morphological, thermal, pharmaceutical, antimicrobial, cytocompatible, and drug delivery properties were investigated. The results demonstrated that the dressings were suitable for delivering the drug at the wound site in a sustained manner and keeping the environment moist for rapid healing. The AMK-loaded AX-CMC films exhibited controlled release of AMK, excellent antibacterial activity, and cytocompatibility. Thus, the AX-CMC composite films appear to be promising bioactive dressing materials for the prevention of wound infections.

The effect of modifying the nanostructure of gelatin fiber scaffolds on early angiogenesisin vitroandin vivo

Early angiogenesis is one of the key challenges in tissue regeneration. Crosslinking mode and fiber diameter are critical factors to affect the adhesion and proliferation of cells. However, whether and how these two factors affect early angiogenesis remain largely unknown. To address the issue, the optimal crosslinking mode and fiber diameter of gelatin fiber membrane for early angiogenesisin vivoandin vitrowere explored in this work. Compared with the post crosslinked gelatin fiber membrane with the same fiber diameter, the 700 nm diameterin situcrosslinked gelatin fiber membrane was found to have smaller roughness (230.67 ± 19 nm) and stronger hydrophilicity (54.77° ± 1.2°), which were suitable for cell growth and adhesion. Moreover, thein situcrosslinked gelatin fiber membrane with a fiber diameter of 1000 nm had significant advantages in early angiogenesis over the two with fiber diameters of 500 and 700 nm by up-regulating the expression of Ang1, VEGF, and integrin-β1. Our findings indicated that thein situcrosslinked gelatin fiber membrane with a diameter of 1000 nm might solve the problem of insufficient blood supply in the early stage of soft tissue regeneration and has broad clinical application prospects in promoting tissue regeneration.

Coaxial fibers of poly(styrene-co-maleic anhydride)@poly(vinyl alcohol) for wound dressing applications: Dual and sustained delivery of bioactive agents promoting fibroblast proliferation with reduced cell adherence

The prevalence of chronic and acute wounds, as well as the complexity of their treatment represent a great challenge for health systems around the world. In this context, the development of bioactive wound dressings that release active agents to prevent infections and promote wound healing, appears as the most promising solution. In this work, we develop an antibacterial and biocompatible wound dressing material made from coaxial electrospun fibers of poly(styrene-co-maleic anhydride) and poly(vinyl alcohol) (PSMA@PVA). The coaxial configuration of the fibers consists of a shell of poly (styrene-co-maleic anhydride) containing a variable concentration of silver nanoparticles (AgNPs) 0.1-0.6 wt% as antibacterial agent, and a core of PVA containing 1 wt% allantoin as healing agent. The fibers present diameters between 0.72 and 1.7 µm. The release of Ag⁺ in a physiological medium was studied for 72 h, observing a burst release during the first 14 h and then a sustained and controlled release during the remaining 58 h. Allantoin release curves showed significant release only after 14 h. The meshes showed an antibacterial activity against Pseudomonas aeruginosa and Bacillus subtilis that correlates with the amount of AgNPs incorporated and the release rate of Ag⁺. Indeed, meshes containing 0.3 and 0.6 wt% of AgNPs showed a 99.99% inhibition against both bacteria. The adherence and cell viability of the meshes were evaluated in mouse embryonic fibroblasts NIH/3T3, observing a significant increase in cell viability after 72 h of incubation accompanied by a reduced adhesion of fibroblasts that decreased in the presence of the active agents. These results show that the material prepared here is capable of significantly promoting fibroblast cell proliferation but without strong adherence, which makes it an ideal material for wound dressings with non-adherent characteristics and with potential for wound healing.

Physically Crosslinked Chitosan/PVA Hydrogels Containing Honey and Allantoin with Long-Term Biocompatibility for Skin Wound Repair: An In Vitro and In Vivo Study

Chitosan/PVA hydrogel films crosslinked by the freeze-thaw method and containing honey and allantoin were prepared for application as wound dressing materials. The effects of the freeze-thaw process and the addition of honey and allantoin on the swelling, the gel content and the mechanical properties of the samples were evaluated. The physicochemical properties of the samples, with and without the freeze-thaw process, were compared using FTIR, DSC and XRD. The results showed that the freeze-thaw process can increase the crystallinity and thermal stability of chitosan/PVA films. The freeze-thaw process increased the gel content but did not have a significant effect on the tensile strength. The presence of honey reduced the swelling and the tensile strength of the hydrogels due to hydrogen bonding interactions with PVA and chitosan chains. Long-term cell culture experiments using normal human dermal fibroblast (NHDF) cells showed that the hydrogels maintained their biocompatibility, and the cells showed extended morphology on the surface of the hydrogels for more than 30 days. The presence of honey significantly increased the biocompatibility of the hydrogels. The release of allantoin from the hydrogel was studied and, according to the Korsmeyer-Peppas and Weibull models, the mechanism was mainly diffusional. The results for the antimicrobial activity against E. coli and S. aureus bacteria showed that the allantoin-containing samples had a more remarkable antibacterial activity against S. aureus. According to the wound healing experiments, 98% of the wound area treated by the chitosan/PVA/honey hydrogel was closed, compared to 89% for the control. The results of this study suggest that the freeze-thaw process is a non-toxic crosslinking method for the preparation of chitosan/PVA hydrogels with long term biocompatibility that can be applied for wound healing and skin tissue engineering.

High Substitution Synthesis of Carboxymethyl Chitosan for Properties Improvement of Carboxymethyl Chitosan Films Depending on Particle Sizes

This study investigated the effect of chitosan particle sizes on the properties of carboxymethyl chitosan (CMCh) powders and films. Chitosan powders with different particle sizes (75, 125, 250, 450 and 850 µm) were used to synthesize the CMCh powders. The yield, degree of substitution (DS), and water solubility of the CMCh powders were then determined. The CMCh films prepared with CMCh based on chitosan with different particle sizes were fabricated by a solution casting technique. The water solubility, mechanical properties, and water vapor transmission rate (WVTR) of the CMCh films were measured. As the chitosan particle size decreased, the yield, DS, and water solubility of the synthesized CMCh powders increased. The increase in water solubility was due to an increase in the polarity of the CMCh powder, from a higher conversion of chitosan into CMCh. In addition, the higher conversion of chitosan was also related to a higher surface area in the substitution reaction provided by chitosan powder with a smaller particle size. As the particle size of chitosan decreased, the tensile strength, elongation at break, and WVTR of the CMCh films increased. This study demonstrated that a greater improvement in water solubility of the CMCh powders and films can be achieved by using chitosan powder with a smaller size.

Gelatin-Based Hybrid Scaffolds: Promising Wound Dressings

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.

Fabrication and characterization of scaffolds containing different amounts of allantoin for skin tissue engineering

Using the skin tissue engineering approach is a way to help the body to recover its lost skin in cases that the spontaneous healing process is either impossible or inadequate, such as severe wounds or burns. In the present study, chitosan/gelatin-based scaffolds containing 0.25, 0.5, 0.75, and 1% allantoin were created to improve the wounds' healing process. EDC and NHS were used to cross-link the samples, which were further freeze-dried. Different in-vitro methods were utilized to characterize the specimens, including SEM imaging, PBS absorption and degradation tests, mechanical experiments, allantoin release profile assessment, antibacterial assay, and cell viability and adhesion tests. The results indicated that the scaffolds' average pore sizes were approximately in the range of 390-440 µm, and their PBS uptake amounts were about 1000% to 1250% after being soaked in PBS for 24 h. Around 70% of the specimens were degraded in 6 days, but they were not fully degraded after 21 days. Besides, the samples showed antibacterial activity against S. aureus and E. coli bacteria. In general, the MTT cell viability test indicated that the cells' density increased slightly or remained the same during the experiment. SEM images of cells seeded on the scaffolds indicated appropriate properties of the scaffolds for cell adhesion.

Skin wounds, the healing process, and hydrogel-based wound dressings: a short review

Skin wounds are damage to the epithelial layer and the integrity of living tissue. The healing mechanism is dynamic and complex, and often treatments with wound dressings help in tissue regeneration, reducing the risk of infections. Polymeric hydrogels become good candidates for wet curing process. These materials prevent dehydration of the tissue and avoid discomfort to the patient when changing the dressing. In this short review, we demonstrate the importance of the healing process, the types of skin wounds, and the hydrogels that are potentially attractive as wound dressings.

A comprehensive survey upon diverse and prolific applications of chitosan-based catalytic systems in one-pot multi-component synthesis of heterocyclic rings

Heterocyclic compounds are among the most prestigious and valuable chemical molecules with diverse and magnificent applications in various sciences. Due to the remarkable and numerous properties of the heterocyclic frameworks, the development of efficient and convenient synthetic methods for the preparation of such outstanding compounds is of great importance. Undoubtedly, catalysis has a conspicuous role in modern chemical synthesis and green chemistry. Therefore, when designing a chemical reaction, choosing and or preparing powerful and environmentally benign simple catalysts or complicated catalytic systems for an acceleration of the chemical reaction is a pivotal part of work for synthetic chemists. Chitosan, as a biocompatible and biodegradable pseudo-natural polysaccharide is one of the excellent choices for the preparation of suitable catalytic systems due to its unique properties. In this review paper, every effort has been made to cover all research articles in the field of one-pot synthesis of heterocyclic frameworks in the presence of chitosan-based catalytic systems, which were published roughly by the first quarter of 2020. It is hoped that this review paper can be a little help to synthetic scientists, methodologists, and catalyst designers, both on the laboratory and industrial scales.