Optimization of electrospun CQDs-Fe3O4-RE loaded PVA-cellulose nanofibrils via central composite design for wound dressing applications: Kinetics and in vitro release study

Wound skin infections can cause significant morbidity and even mortality. Cellulose nanofibrils (CNFs) are a type of nano cellulose that have reached notable attention due to their inimitable properties. In this study, in order to prepare a novel wound dressing, CNFs are composited with poly (vinyl alcohol) (PVA) to enhance mechanical properties and increase cell proliferation and migration. Also, carbon quantum dots (CQDs)- Fe₃O₄ was introduced as a novel antibacterial, and rosemary extract (RE) was composited with this to reduce its cell toxicity. PVA - CNFs/ CQDs- Fe₃O₄- RE nanofiber was prepared using the electrospinning method. Then, to maximize tensile strength, total elongation, and percentage swelling of PVA - CNFs/ CQDs- Fe₃O₄- RE electrospun nanofiber, parameters of crosslinking duration and the concentration of CQDs- Fe₃O₄-RE were optimized employing central composite design, and optimized electrospun nanofiber (OEN) as a novel wound dressing was prepared. Results exhibited, the high antibacterial properties of CQDs-Fe₃O₄-RE. Also, CNFs and CQDs- Fe₃O₄-RE increased the tensile strength of OEN. Moreover, CNFs and RE reduce wound area percentages and increase the percentage of cell viability, respectively. Therefore, OEN was introduced as a suitable wound dressing due to its appropriate surface roughness, mechanical properties, WVTR, biodegradation, prolonged release, non-toxicity, and high cell proliferation and migration ability.

Alternative modification by grafting in bamboo cellulose nanofibrils: A potential option to improve compatibility and tunable surface energy in bionanocomposites

Chemical modification in surface of cellulose nanofibrils CNFs (20 nm) from an endemic and non-significant value-added, Argentine bamboo, was developed. The modification in the CNFs was carried out with three simple routes using a low molecular weight polylactic acid synthesized in our laboratory (PLA1). The first step comprises of protection of the hydroxyl groups of PLA1 through a benzoylation (PLA1Bz). The next step consisted of the activation of carboxyl groups using thionyl chloride and the last reaction was the grafting of the modified PLA onto the CNFs (PLA1Bz-g-CNF). The covalently functionalization is confirmed by spectroscopically techniques as well as PLA1Bz-g-CNFs were characterized by thermal analyses. The PLA1Bz-g-CNFs were taken up such as nanocharges to improve properties of compatibilization and changing surface properties in films based on PLA. The comparison between the films with PLA1Bz-g-CNFs with respect to the physic mixture of the components (PLA1Bz/CNF), shows an improvement in the thermal, mechanical, and surface properties of the material, particularly when 5% of PLA1Bz-g-CNFs was added. The dispersive (γS D) component of film is increased in 36.1 mN/m respect to 29.3 mN/m from the films obtained with the physic mixture nanofibrils without modification and a plasticizing effect was noticed in the final material.

Inflammatory responses and tissue reactions to wood-Based nanocellulose scaffolds

Two wood-derived cellulose nanofibril (CNF) porous scaffolds were prepared by TEMPO-oxidation and carboxymethylation. The effects of these scaffolds on the production of inflammatory cytokines by human macrophage-like cells (U937) was profiled in vitro after 1 and 3 days and in subcutaneous tissues of rats after 4 and 30 days, using PCR and Multiplex arrays. Tissue culture plates (TCP) and gelatin scaffolds served as controls in vitro and in vivo respectively. After 3 days in vitro, there was no significant difference between the effects of CNF scaffolds and TCP on the production of chemokines/growth factors and pro-inflammatory cytokines. At day 4 in vivo there was significantly higher gene expression of the anti-inflammatory IL-1Ra in the CNF scaffolds than the gelatin scaffold. Production of IL-1β, IL-6, MCP-1, MIP-1α CXCL-1 and M-CSF was significantly less than in the gelatin, demonstrating an early mild inflammatory response. At day 30, both CNF scaffolds significantly stimulated the production of the anti-inflammatory cytokine IL-10. Unlike gelatin, neither CNF scaffold had degraded 180 days post-implantation. The slow degradation of CNF scaffolds resulted in a foreign body reaction, with high production of IL-1β, IL-2, TNF-α, IFN-ϒ, MCP-1, MIP-1α, M-CSF, VEGF cytokines and expression of MMP-9 gene. The surface chemistry of the CNF scaffolds elicited a modest effect on cytokine production and did not shift the inflammatory profile in vitro or in vivo. The decisive role in development of the foreign body reaction was the slow degradation of the CNF scaffolds.