Biofuncionalización de superficies a base de fibroína de seda para su potencial uso en aplicaciones cardiovasculares

En el presente trabajo, se biofuncionalizaron con heparina películas fabricadas a base de fibroína (SF) y polivinil alcohol (PVA) utilizando dos técnicas diferentes, la primera por acople de carbodiimida y la segunda por aprovechamiento de interacciones electrostáticas, buscando conseguir un comportamiento antitrombogénico en la superficie de las películas fabricas para su potencial uso como biomateriales para la fabricación de implantes cardiovasculares. Las muestras biofuncionalizadas fueron sometidas a una prueba de coagulación de sangre para verificar el éxito de dicha biofuncionalización. Los resultados mostraron que las muestras biofuncionalizadas por acople de carbodiimida, además de presentar una actividad antitrombogénica superior a las biofuncionalizadas por aprovechamiento de interacciones electrostáticas, presentaban valores de ángulos de contacto más cercanos a los de los materiales para la fabricación de implantes cardiovasculares, y que también, la biofuncionalización no afecta significativamente las propiedades mecánicas y superficiales de las películas fabricadas.

In the present work, fibroin, and polyvinyl alcohol (PVA) - based films were biofunctionalized using two different techniques, the first by carbodiimide coupling and second by exploiting electrostatic interactions, seeking to achieve antithrombogenic behavior on the surface of the manufactured films for their potential use as biomaterials for the manufacture of cardiovascular implants. The biofunctionalized samples were submitted to the blood clotting test to verify the success of said biofunctionalization. The results showed that the samples biofunctionalized by carbodiimide coupling, in addition to presenting a higher antithrombogenic activity than those biofunctionalized by taking advantage of electrostatic interactions, presented contact angles values closer to those of the materials for the manufacture of cardiovascular implants, and that also, the biofunctionalization does not significantly affect the mechanical and surface properties of the fabricated films

Development and Evaluation of Chitosan-Based Food Coatings for Exotic Fruit Preservation.

Chitosan has gained agro-industrial interest due to its potential applications in food preservation. In this work, chitosan applications for exotic fruit coating, using feijoa as a case of study, were evaluated. For this, we synthetized and characterized chitosan from shrimp shells and tested its performance. Chemical formulations for coating preparation using chitosan were proposed and tested. Mechanical properties, porosity, permeability, and fungal and bactericidal characteristics were used to verify the potential application of the film in the protection of fruits. The results indicated that synthetized chitosan has comparable properties to commercial chitosan (deacetylation degree > 82%), and, for the case of feijoa, the chitosan coating achieved significant reduction of microorganisms and fungal growth (0 UFC/mL for sample 3). Further, membrane permeability allowed oxygen exchange suitable for fruit freshness and natural physiological weight loss, thus delaying oxidative degradation and prolonging shelf-life. Chitosan's characteristic of a permeable film proved to be a promising alternative for the protection and extension of the freshness of post-harvest exotic fruits.

Isolation of chitosan from Ganoderma lucidum mushroom for biomedical applications.

Chitin biopolymer production and its by-product chitosan show great potential. These biomaterials have great applicability in various fields because they are non-toxic, biodegradable, biocompatible, and have antimicrobial effects. The most common source of chitin and chitosan is the crustaceous shell; however, mushrooms are an alternative source for isolating these biopolymers because their cellular wall has a high content of chitin, which may be transformed into chitosan through a deacetylation reaction. The main objective of this research was to obtain chitosan through the deacetylation of chitin isolated from the Ganoderma lucidum basidiomycetes mushroom, which is obtained through biotechnological culture. The material characterization was performed using X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and an evaluation of cytotoxicity comparing the results obtained with results for commercial chitosan. Protocol results showed that chitosan obtained from this mushroom had a significant similitude with commercial chitosan, yet the one obtained using P2 protocol was the one that rendered the best results: including diffractogram peaks, characteristic infrared analysis bands, and an 80.29 % degree of deacetylation. Cytotoxicity in vitro testing showed that the material was non-toxic; furthermore, it rendered very promising information regarding the evaluation of future applications of this biomaterial in the field of biomedicine.

Comparison of extraction methods of chitin from Ganoderma lucidum mushroom obtained in submerged culture.

The chitin was isolated from the Ganoderma lucidum submerged cultures mycelium as potential source of chitin under biotechnological processes. The extraction of chitin was carried out through 5 different assays which involved mainly three phases: pulverization of the mushroom, deproteinization of the mycelia with NaOH solution, and a process of decolorization with potassium permanganate and oxalic acid. The chitin contents extracted from 9-day mycelia were 413, 339, 87, 78, and 144 mg/g(-1) (milligrams of chitin/grams of dry biomass) for A1, A2, A3, A4, and A5, respectively. Obtained chitin was characterized by X-Ray Diffraction (XRD), by Fourier transform infrared spectroscopy (FTIR), and by thermal analysis (TGA). The results showed that Ganoderma lucidum chitin has similar characteristic of chitin from different fonts. The advantage of the biotechnological processes and the fact that Ganoderma lucidum fungus may be used as a potential raw material for chitin production were demonstrated.

PRODUCCIÓN DE MATRICES DE QUITOSANO EXTRAÍDO DE CRUSTÁCEOS / PRODUCTION OF SCAFFOLDS USING CHITOSAN EXTRACTED FROM CRUSTACEANS

El quitosano está presente en el caparazón de los crustáceos, y desde hace algún tiempo ha sido utilizado en el campo de la medicina y la ingeniería de tejidos para la fabricación de matrices de crecimiento celular. En este estudio se extrajo quitosano de caparazón de crustáceos y se propuso un método sencillo para fabricar matrices con microestructura controlada. Las matrices fueron preparadas por congelación y liofilización de soluciones de quitosano y luego fueron caracterizadas por microscopía electrónica de barrido. La difracción de rayos X del quitosano extraído mostró un espectro acorde con una fuente comercial del material, evidenciando la efectividad del protocolo de extracción. La microscopía mostró poros ovalados y circulares distribuidos en todo el volumen de las muestras, con diámetros de poros entre 100 µm y 150 µm. Lo anterior demuestra que el método de producción propuesto proporciona un punto de partida para la fabricación de matrices de crecimiento celular.

Chitosan is present in crustacean shells and it has been used in the fields of medicine and tissue engineering for the construction of scaffolds that support cell growth. In this study, chitosan was extracted from crustacean shells and processed into scaffolds with controlled microstructure using a simple processing method presented herein. The scaffolds were prepared by freezing and lyophilization of chitosan solutions and were characterized by scanning electron microscopy. The results showed a chitosan with an X-ray diffraction spectrum similar to that of a commercial chitosan, thus demonstrating the effectiveness of the extraction protocol. Microscopy showed oval and circular pores distributed on the bulk sample, with pore diameters between 100 µm and 150 µm. This shows that the proposed fabrication method provides a starting point for the construction of porous scaffolds that may support cell growth.