Hydrogel bioink based on clickable cellulose derivatives: Synthesis, characterization and in vitro assessment.

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.

Multi-layer dressing made of laminated electrospun nanowebs and cellulose-based adhesive for comprehensive wound care.

In this work, multi-layer wound dressing was made of laminated layers of electrospun fibers supported by adhesive sheet. Graft copolymerization of methyl methacrylate (MMA) and 2-Ethyl-1-hexyl acrylate (EHA) onto carboxymethyl cellulose (CMC) was conducted to obtain an adhesive sheet with 1.52 (N/cm2) loop tack, 1.7 (N/cm) peel strength and 25 s shear strength. Diclofenac sodium, anti-inflammatory drug, was loaded to the adhesive sheet with encapsulation efficiency 73%. The contact layer to wound was made of synthesized anti-bleeding agents, chitosan iodoacetamide (CI) loaded into electrospun polyvinyl alcohol (PVA) fibers. It was fabricated from fiber diameter 300 nm by electrospinning of 5% wt/v of CI (D.S. 18.7%) mixed with 10% wt/v PVA, at 20 kV and 17 cm airgap. The second, pain-relief layer was fabricated by encapsulating up to 50% wt/wt of capsaicin into gelatin nanofibers (197 nm) crosslinked by glyoxal. The third, antimicrobial layer was fabricated from PVA electrospun fibers loaded with 2% wt/wt gentamicin. Biocompatibility test showed insignificant adverse effects of the fabricated layers on fibroblast cells. Animal test on rat showed accelerated wound healing from 21 to 7 days for the multi-layer dressing. Histopathological findings corroborated the intactness of the epidermis layer of the treated samples.

Cellulose-based click-scaffolds: Synthesis, characterization and biofabrications.

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 ß-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 ß -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.