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Hydrogel is considered as a promising candidate for bioink in terms of biocompatibility, biodegradability, printability and supporting cellular behavior. Recently, carbohydrates derivatives containing alkyne and azide pendant functional groups have been used in medical applications due to their improved chemical, biological, functional properties, and their amenability for chemical reactions under mild conditions. In this work, a novel bioink was developed based on azide and alkyne of cellulose derivatives. Azido-hydroxyethyl cellulose (D.Sazido = 0.04) was synthesized via open-ring reaction of 1-azido-2,3-epoxypropane and characterized spectroscopically and titrimetrically. Alkyne derivative, propargyl carboxymethyl cellulose (D.Spropargyl = 1.72) was synthesized through coupling reaction with propargylamine in the presence of EDC and NHS. The click-gel scaffold was obtained by mixing the two novel candidates in the presence of copper (I) catalyst. Extrusion bio-plotting experiment was successfully conducted of the two solutions into coagulant Cu (I)/DMSO solutions and demonstrated the possibility of using the clickable cellulose derivatives as bioink precursors. Chemical and physical properties of the click-gel were demonstrated. The biocompatibility assay of the prepared click-gels showed high level of viability in the human skin fibroblast cells (HFB4) at concentration 100 μg/mL.

In this work, polyvinylpyrrolidone nanofibers were electrospun incorporated with lecithin, zero-charge natural segment, as non-biofouling nanofiltration membrane with tunable porous structures. Optimum conditions were studied to obtain nano-pore size capable of nano-scaled objects reduction using needle and needleless electrospinning apparatuses. Fiber diameters were in proportional relationship with PVP concentrations to range from 1.2 um to 34 nm at 10 to 5% wt/v PVP respectively. Microcrystalline cellulose (MCC) was added and PVP fibers were photo-crosslinked to enhance the mechanical strength. Mechanical properties of electrospun fibers were enforced up to 279% in the presence of microcrystalline cellulose while increased by 125% when exposed to photo-crosslinking for 8 h by UV-light radiation. UV-crosslinking has significantly improved the hydrophobicity of the final mat to report contact angle bigger than 90° at 16 h. Protein adhesion test was conducted to indicate the capability of the electrospun membrane to bypass the blood-plasma products. Zero protein adhesion was recorded by adding only 2% wt/v of lecithin.

Punica granatum peel (PGP) is widely used in traditional medicinal purposes for chronic wounds owing to containing natural phenolics active components. In current study, active wound dressing hydrogel for chronic wound healing was prepared based on P. granatum peel crude extract (PGPC), ethyl acetate fraction (PGPEA) and their silver nanoforms (Ag-NPs). Methacrylated chitosan was synthesized as precursor to hydrogel and crosslinked by divinyl sulfone (DVS) in mild condition. Hydrogel was fully characterized by spectral morphological, mechanical and physical analyses. The integration of PGPEA silver nanoforms was formed with particle size of 15–56 nm to show minimum inhibitory concentration (MIC) equal 63 for Staphylococcus aureus and 125 for Pseudomonas aeruginosa. The hydrogel-based wound dressing with/without the active ingredients showed acceptable cytotoxicity against fibroblast human cells for PGPC and PGPEA fraction over the silver nanoforms. Rat as animal model was considered to show the impact of the active wound dressing on diabetic wounds which was proved by histopathological examination. In addition, the significant intensity of immunopositivity signals of the transforming growth factor beta (TGF-β1) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in the epidermal cells have revealed the efficiency of Ag NPs-PGPEA-chitosan hydrogel for chronic wound curing.

Carbohydrates derivatives containing propargyl pending functional groups have been used in medical applications due to their improved chemical, biological, and functional properties. In this work, azide and alkyne pendant functional groups were introduced onto ethyl cellulose (EC) and β-cyclodextrin respectively in order to demonstrate the ability of scaffold formation by click chemistry. Technically, Azido-ethyl cellulose (D.S.Azido 0.19) and 2, 3, 6-O- propargylated β –cyclodextrin were synthesized and characterized as click-triggered candidates. The click-gel scaffold was obtained by mixing the two novel candidates in the presence of copper catalyst. Azido-EC was considered to produce clickable electrospun fibers blended with EC (290–620 nm) at 20 kV in order to functionalized EC substrate bearing azide groups to be amenable towards immobilization of an alkyne-terminated bio-molecules. The biocompatibility assay of the prepared click-triggered candidates showed very high level of viability in the human skin fibroblast cells (HFB4) at concentration 100 μg/ml.

Conjugated linoleic acids (CLA) as essential fatty acids (EFAs) have shown medical significance towards wound healing process. However, EFAs whose chemical structures possess unsaturated double bonds are unstable to environmental degradation. Encapsulation of EFAs into protective layer was the basic approach to avoid such degradation. In this work, CLA was extracted from sunflower oil, purified and characterized by spectral analysis. CLA was loaded into two different substrates namely hydrophobic, cellulose acetate (CA), and hydrophilic, liposomal emulsions of poly (vinylalcohol) (PVA) and gelatin, polymers. Electrospinning parameters were optimized to obtain clear, smooth and bead-free fibers. 12 % wt/v of CA shows bead-free fibers with diameter in range of 440-300 nm loaded with CLA up to 26% wt/wt. While, CLA (3% wt/wt) is encapsulated into the liposomal emulsions of PVA and gelatin with average fiber diameters 252-400 nm and 120-200 nm respectively. The CLA encapsulation, morphology of the electrospun fibers, and fiber diameter were examined using scanning electron microscopy (SEM). Viscosity and conductivity of the prepared solutions for electrospinning were demonstrated. Biocompatibility was evaluated by measuring cell proliferation of skin fibroblast cells. The release profile was investigated by UV- Visible spectroscopy. CLA loaded into the electrospun showed lower peroxide values (PV) of CLA.

Edible packaging materials of encapsulated essential oils in biopolymers have been investigated to provide an effective and safe approach for food preservation. In this study, chitosan-based emulsions made of liposomes loaded with thyme essential oil (TEO) were investigated to extend the shelf-life of Karish cheese. Liposomal chitosan emulsions were prepared via reverse-phase evaporation method and its macrostructure was demonstrated. Chitosan-based emulsions with TEO/liposomes, prepared by 2% wt/v chitosan solutions, are stable over 2 months. GC/MS analysis of TEO showed that thymol and p-cymene are the major compounds with 30 and 13.7% respectively. Antimicrobial activities were assessed via visible microbial growth method and total bacteria counts of mesophilic, phsychrotrophic bacteria, yeast and mould over 4 weeks. Visible microbial growth test showed an explicit microbial growth, by the second week, for all cheese samples that are not coated or coated with chitosan solutions. Cheese samples coated with chitosan containing TEO 1 and 2 % v/v stayed safe with accepted microbial counts till the end of third week. However, samples coated with liposomal chitosan emulsions encapsulated TEO 1and 2% v/v remained in acceptable appearance and microbial counts up to 4 weeks. Coatings showed neutral effects on moisture content, pH and titratable acidity.

The moist dressing has been taken as an approach to maintain a wet environment for the wound and accelerate its healing process. Recently, more functionality has been imparted to wound dressings to monitor changes in skin pH and visually indicate the wound healing status. However, providing a biocompatible pH-sensing hydrogel made of green components, at a neutral medium, is yet to investigate. In this work, pH-sensitive natural dye, Curcuma Longa extract (CLE), was utilized as an easy and cost-effective pH-sensitive indicator. CLE was loaded in hydrogel made of hydroxyethyl cellulose grafted with green monomer, itaconic acid (IA), to prepare transparent, soft, and neutral pH-sensitive wound dressing. IA concentrations tuned gel porous structure (370–100 µm), mechanical (686–1186 N, load at break), swelling (up to1839% at neutral medium), and release properties. Hydrogel showed higher release percentages at pH (7.4), and longer release profiles at pH (8 ± 0.2) which suits wound healing applications. The coloristic properties of the CLE as a function of pH were confirmed by UV–Vis spectroscopy. Hydrogel matrices, loaded on cotton gauze and submerged in different pH buffer solutions, showed explicit color changes from visibly yellow for pH ≤ 7 and dark red for pH > 7.

Uncontrolled hemorrhage continues to be the leading cause of death from traumatic injuries both in the battlefield and in the civilian life. Chitosan is among the very few materials that have made the short list of military recommended field-deployable hemostatic dressings. However, the detailed mechanism of its action is still not fully understood. Moreover, in the cases when patients developed coagulopathy, the efficacy of the dressings rely solely on those mechanisms that work outside of the regular blood coagulation cascade. In addition to the well-known erythrocyte agglutination, we proposed to use the reactive N-iodoacetyl group on a new chitosan derivative to accelerate hemostasis. In this paper, we describe the synthesis of chitosan iodoacetamide (CI) with considerations of the stoichiometry among the reagents, the choice of solvent, the pH of the reaction medium, and the reaction time. The reaction was confirmed by FT-IR, 1H and 13C NMR, elemental analysis, iodine content analysis, and SEM-EDS. Water contact angle measurements and Erythrocyte Sedimentation Rate (ESR) method were used to evaluate the hemostatic potential of the newly synthesized CI as a function of their degree of substitution (DS). The range of DS was 5.9% to 27.8% for CI. The mid-range of DS gave the best results for the ESR. CIs exhibit favorable cytocompatibilities up to DS 18.7 compared to the generic unmodified chitosan. In general, the biocompatibility of chitosan iodoacetamide slightly declined with increasing the iodide content up to DS 21.5 owing to its affinity to SH groups of cells.

a b s t r a c t A method to impregnate silver nanoparticles (AgNPs) into different polysaccharides substrates (cellulose powder (CP), microcrystalline cellulose (MCC), carboxymethyl cellulose (CMC) and chitosan (Chit)) by using glucose as reducing agent, is presented. X-ray diffraction analyses of polysaccharides coated with AgNPs showed the formation of silver particle sizes in the range of 3.7–5.6 nm and have almost spherical shape. The entire prepared composite shows antimicrobial effect. The antibacterial activity of polysaccharides loaded with silver nanoparticles was evaluated against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) bacteria. The results suggest excellent antibacterial activity.