Preparation and characterization of salicylic acid grafted chitosan electrospun fibers

Chitosan (chi) and its modified forms as electrospun nanofibers have potential applications in advanced water treatment and biomedicine. Polyethylene oxide (PEO) is an additive commonly used to facilitate the formation of chitosan electrospun fibers because PEO (Mw ≥ 400 kDa) affords chain entanglement that stabilize the electrospinning jet, leading to enhanced formation of chi-based electrospun fibers. Herein, we report on the preparation of chitosan grafted with salicylic acid and its utility to afford improved electrospun fibers with low molecular weight (LMw) PEO (Mw » 100 kDa). A comparison of the interactions between original and grafted chitosan with PEO reveals that stable supramolecular assemblies are established between grafted chitosan and PEO, which provides support that such supramolecular interactions favor formation of chitosan electrospun fibers. Moreover, a porous chitosan electrospun nanofiber was prepared through physical treatment that reveals notably higher (ca. 4-fold) dye uptake than the pristine (unmodified) chitosan electrospun nanofibers.

An Overview of the Design of Chitosan-Based Fiber Composite Materials

Chitosan composite fibrous materials continue to generate significant interest for wastewater treatment, food packaging, and biomedical applications. This relates to the relatively high surface area and porosity of such fibrous chitosan materials that synergize with their unique physicochemical properties. Various methods are involved in the preparation of chitosan composite fibrous materials, which include the modification of the biopolymer that serve to alter the solubility of chitosan, along with post-treatment of the composite materials to improve the water stability or to achieve tailored functional properties. Two promising methods to produce such composite fibrous materials involve freeze-drying and electrospinning. Future developments of such composite fibrous materials demands an understanding of the various modes of preparation and methods of structural characterization of such materials. This review contributes to an understanding of the structure–property relationships of composite fibrous materials that contain chitosan, along with an overview of recent advancements concerning their preparation.

Extraction, physicochemical characterization, and morphological properties of chitin and chitosan from cuticles of edible insects

As an alternative, cuticles from edible insects was proposed as an unconventional but viable source of chitin and chitosan. The chitin present in the mealworm's (Tenebrio molitor) cuticles was obtained biotechnologically in one step of enzymatic deproteinization and after deacetylated. Differences in the physicochemical characteristics and the properties of the cuticles, chitin, and chitosan were investigated in this study. Commercial chitosan was used as a reference sample to validate the methods used. The enzymatic deproteinization used to obtain chitin showed an efficiency of 85%. The global yield of the process (cuticle-to-chitosan) was 31.9%. The characterization results of these polymers using DSC, FT-IR, XRD, TGA, and SEM techniques demonstrate consistency with the degree of deacetylation of the obtained chitosan, allowing the differentiation between chitin and chitosan. This study suggests that the wastes of edible insect breeding should be collected and evaluated as an alternative of chitin/chitosan source.

Caracterização química e efeito cicatrizante de quitosana, com baixos valores de massa molar e grau de acetilação, em lesões cutâneas

Inúmeras pesquisas buscam fármacos com propriedades cicatrizantes, capazes de reparar lesões cutâneas. O objetivo deste estudo foi caracterizar quimicamente uma quitosana e avaliar seus efeitos cicatrizantes em lesões cutâneas de ratos. A quitosana foi caracterizada quanto à viscosidade, massa molar, grau de acetilação, análise elementar, termogravimetria e espectroscopia na região do infravermelho. As propriedades cicatrizantes da quitosana foram avaliadas, para isso ratos adultos foram submetidos à excisão tecidual e tratados por 21 dias, sendo avaliados parâmetros macroscópicos, semanalmente, e microscópicos, ao final do experimento. A quitosana apresentou viscosidade de 5 mPa s, baixo grau de acetilação (GA=5,9%) e massa molar (132,0 kDa). Por análise elementar observou-se que a composição da quitosana se aproxima da fórmula C6H11O4N, suas principais bandas características foram observadas no espectro de infravermelho e a curva termogravimétrica mostrou que esta apresenta somente duas etapas de decomposição. Não houve diferença significativa na histologia, no 21º dia da lesão, entre os grupos controle e tratado, porém, macroscopicamente, a quitosana promoveu redução de 81,4% da largura das lesões, porcentagem significativamente superior à observada no grupo controle (71,2%), auxiliando a cura de lesões cutâneas, o que reforça seu potencial de aplicação médica.