Lawsone-encapsulated chitosan/polyethylene oxide nanofibrous mat as a potential antibacterial biobased wound dressing

Porous scaffolds for skin tissue engineering were fabricated by freeze-drying the mixture of collagen and chitosan solutions. Glutaraldehyde (GA) was used to treat the scaffolds to improve their biostability. Confocal laser scanning microscopy observation confirmed the even distribution of these two constituent materials in the scaffold. The GA concentrations have a slight effect on the cross-section morphology and the swelling ratios of the cross-linked scaffolds. The collagenase digestion test proved that the presence of chitosan can obviously improve the biostability of the collagen/chitosan scaffold under the GA treatment, where chitosan might function as a cross-linking bridge. A detail investigation found that a steady increase of the biostability of the collagen/chitosan scaffold was achieved when GA concentration was lower than 0.1%, then was less influenced at a still higher GA concentration up to 0.25%. In vitro culture of human dermal fibroblasts proved that the GA-treated scaffold could retain the original good cytocompatibility of collagen to effectively accelerate cell infiltration and proliferation. In vivo animal tests further revealed that the scaffold could sufficiently support and accelerate the fibroblasts infiltration from the surrounding tissue. Immunohistochemistry analysis of the scaffold embedded for 28 days indicated that the biodegradation of the 0.25% GA-treated scaffold is a long-term process. All these results suggest that collagen/chitosan scaffold cross-linked by GA is a potential candidate for dermal equivalent with enhanced biostability and good biocompatibility.

Chitosan is widely used in the biomedical field due its chemical and pharmacological properties. However, intake of chitosan results in renal tissue accumulation of chitosan and promotes an increase in calcium excretion. On the other hand, the effect of chitosan on the formation of calcium oxalate crystals (CaOx) has not been described. In this work, we evaluated the antioxidant capacity of chitosan and its interference in the formation of CaOx crystals in vitro. Here, the chitosan obtained commercially had its identity confirmed by nuclear magnetic resonance and infrared spectroscopy. In several tests, this chitosan showed low or no antioxidant activity. However, it also showed excellent copper-chelating activity. In vitro, chitosan acted as an inducer mainly of monohydrate CaOx crystal formation, which is more prevalent in patients with urolithiasis. We also observed that chitosan modifies the morphology and size of these crystals, as well as changes the surface charge of the crystals, making them even more positive, which can facilitate the interaction of these crystals with renal cells. Chitosan greatly influences the formation of crystals in vitro, and in vivo analyses should be conducted to assess the risk of using chitosan.

Chitosan-based nanofibers with an average fiber diameter controllable from a few microns down to approximately 40 nm and a narrow size distribution were fabricated by electrospinning solutions containing chitosan, polyethylene oxide (PEO), and Triton X-100. Rheological study showed a strong dependence of spinnability and fiber morphology on solution viscosity and thus on chitosan-to-PEO ratio. The nanofibers can be deposited either as a nonwoven mat or as a highly aligned bundle of controllable size. Potential use of this nanofibrous matrix for tissue engineering was studied by examining its integrity in water and cellular compatibility. It was found that the matrix with a chitosan/PEO ratio of 90/10 retained excellent integrity of the fibrous structure in water. Experimental results from cell stain assay and SEM imaging showed that the nanofibrous structure promoted the attachment of human osteoblasts and chondrocytes and maintained characteristic cell morphology and viability throughout the period of study. This nanofibrous matrix is of particular interest in tissue engineering for controlled drug release and tissue remodeling.