Tubular electrospun scaffolds tested in vivo for tissue engineering

Tissue engineering has been widely used for its great variety of functions. It has been seen as a solution to satisfy the need for vascular substitutes like small diameter vessels, veins, and nerves. One of the most used methods is electrospinning, due to the fact that it allows the use of various polymers, sizes, mandrels and it can adjust the conditions to create personalized scaffolds. For the creation of scaffolds is fundamental to understand the advantages and disadvantages of each polymer, of this, will depend the biodegradability, biocompatibility, porosity, cellular adhesion, and cell proliferation as it is essential to mimic the extracellular matrix and provide structural support for the cells. The aim of this review was to investigate which materials are being used for the creation of tubular scaffolds by electrospinning. Here we selected only in vivo evaluation to demonstrate remodeling of the grafts into native-like tissues, in vitro evaluations had been excluded from this review. We analyze the conditions like speed, distance and voltage and the modifications like growth factors and combinations of natural and synthetic polymers that allow the authors to have a functional scaffold that will suit its purpose

Biopelículas a base de pectina de cáscara de naranja (Citrus sinensis): Caracterización física, química y estructural

La naranja es uno de los cultivos con mayor plantación en México y se visualiza un crecimiento para los próximos años. Derivado de las actividades de la agroindustria se producen residuos de cáscara de naranja, la cual por su alto contenido de pectina es apropiado para obtener bioplásticos, el cual es el objetivo principal de este trabajo. La extracción de la pectina se realizó mediante hidrólisis ácida, utilizando ácido cítrico al 0,1% y como agente plastificante glicerol a concentraciones de 3%, 4% y 5% para determinar la resistencia y rigidez óptima de la biopelícula. Se obtuvieron biopelículas flexibles, libres de poros y espacios intersticiales en la superficie del material. La biopelícula con composición de glicerol al 5% presentó características uniformes, con mejor flexibilidad y apariencia física en comparación con los de 3% y 4%. Mediante el análisis del FTIR se determinó que el polímero (pectina) mostró una banda característica de absorción del grupo -OH a 3300 cm-1, del grupo C-O a 1023 cm-1 y para el grupo COOH a 1732 cm-1 característica de un material biodegradable. De acuerdo con el análisis elemental de la biopelícula, se encontró que está compuesta por C, H, N y S, lo cual lo hace un material biodegradable no tóxico y amigable con el ambiente

Physicomechanical behavior of composites of polypropylene, and mineral fillers with different process cycles

In this work, a development of composites of polypropylene [PP] with mineral fillers [M] of talc and calcium carbonate [CaCO3] by co-extrusion and injection techniques were carried out. In the preparation of the mixtures, was used the rheometric analysis to define the optimum temperature of the extrusion process, and a weight ratio of 80:20 PP: fillers was maintained, while for the injection molding process six generations of PP and its compounds were obtained to study the rheological, thermal, morphological and mechanical properties of the new series of PPnM composites formed from a recycled matrix and the PPMn series reprocessed compounds for up to six cycles. The results allowed correlating the changes due to the thermal history and the influence of adding the mineral fillers. The mechanical characterization in the reprocessed matrix indicated a 6.0% decrease in tensile strength and an increase in flexural strength of 9.9%. Likewise, the compounds showed an increase in tensile strength of 11.7%, while flexural strength reached 35.8%. From the thermogravimetric analysis, the degradation temperature in the matrix gradually decreased from 406.5 °C to 364.3 °C, for the sixth generation with respect to the virgin material by the injection process; meanwhile, for the compounds was maintained around 410 °C indicating an optimal interaction, these results could be contrasted with the colorimetric analysis. Finally, re-injection led to a significant decrease in the size of the talc and CaCO3 particles; the sizes were estimated from microstructural analysis from Scanning Electron Microscope.En este trabajo, se llevó a cabo el desarrollo de compuestos de polipropileno [PP] con cargas minerales [M] de talco y carbonato de calcio [CaCO3] mediante técnicas de coextrusión e inyección. En la preparación de las mezclas, se utilizó el análisis reométrico para definir la temperatura óptima del proceso de extrusión, y se mantuvo una relación 80:20 en peso de PP con las cargas, mientras que para el proceso de moldeo por inyección se obtuvieron seis generaciones de PP y sus compuestos para estudiar las propiedades reológicas, térmicas, morfológicas y mecánicas de las nuevas series de compuestos de PPnM formados a partir de una matriz reciclada y los compuestos reprocesados de la serie PPMn hasta seis ciclos. Los resultados permitieron correlacionar los cambios debidos al historial térmico y la influencia de incorporación de las cargas minerales. La caracterización mecánica en la matriz reprocesada indicó una disminución del 6,0% en la resistencia por tracción y un aumento de la resistencia por flexión del 9,9%. Así mismo, los compuestos mostraron aumento de la resistencia a la tracción del 11,7%, mientras que la resistencia a la flexión alcanzó el 35,8%. Por otro lado, la temperatura de degradación en la matriz disminuyó gradualmente de 406,5 °C hasta 364,3 °C, para la sexta generación con respecto al material virgen; mientras tanto, la temperatura de degradación de los compuestos se mantuvo alrededor de 410 °C indicando una óptima interacción, estos resultados se pudieron contrastar con el análisis colorimétrico. Finalmente, la re-inyección condujo a una disminución significativa del tamaño de las partículas de talco y CaCO3, los tamaños fueron estimados a partir del análisis microestructural mediante Microscopía Electrónica de Barrido (SEM)

Physicomechanical behavior of composites of polypropylene, and mineral fillers with different process cycles

In this work, a development of composites of polypropylene [PP] with mineral fillers [M] of talc and calcium carbonate [CaCO3] by co-extrusion and injection techniques were carried out. In the preparation of the mixtures, was used the rheometric analysis to define the optimum temperature of the extrusion process, and a weight ratio of 80:20 PP: fillers was maintained, while for the injection molding process six generations of PP and its compounds were obtained to study the rheological, thermal, morphological and mechanical properties of the new series of PPnM composites formed from a recycled matrix and the PPMn series reprocessed compounds for up to six cycles. The results allowed correlating the changes due to the thermal history and the influence of adding the mineral fillers. The mechanical characterization in the reprocessed matrix indicated a 6.0% decrease in tensile strength and an increase in flexural strength of 9.9%. Likewise, the compounds showed an increase in tensile strength of 11.7%, while flexural strength reached 35.8%. From the thermogravimetric analysis, the degradation temperature in the matrix gradually decreased from 406.5 °C to 364.3 °C, for the sixth generation with respect to the virgin material by the injection process; meanwhile, for the compounds was maintained around 410 °C indicating an optimal interaction, these results could be contrasted with the colorimetric analysis. Finally, re-injection led to a significant decrease in the size of the talc and CaCO3 particles; the sizes were estimated from microstructural analysis from Scanning Electron Microscope

Morphological Study of Chitosan/Poly (Vinyl Alcohol) Nanofibers Prepared by Electrospinning, Collected on Reticulated Vitreous Carbon

In this work, chitosan (CS)/poly (vinyl alcohol) (PVA) nanofibers were prepared by using the electrospinning method. Different CS concentrations (0.5, 1, 2, and 3 wt %), maintaining the PVA concentration at 8 wt %, were tested. Likewise, the studied electrospinning experimental parameters were: syringe/collector distance, solution flow and voltage. Subsequently, the electrospun fibers were collected on a reticulated vitreous carbon (RVC) support for 0.25, 0.5, 1, 1.5, and 2 h. The morphology and diameter of the CS/PVA nanofibers were characterized by scanning electron microscopy (SEM), finding diameters in the order of 132 and 212 nm; the best results (uniform fibers) were obtained from the solution with 2 wt % of chitosan and a voltage, distance, and flow rate of 16 kV, 20 cm, and 0.13 mL/h, respectively. Afterwards, a treatment with an ethanolic NaOH solution was performed, observing a change in the fiber morphology and a diameter decrease (117 ± 9 nm)

In Vitro Modulation of Spontaneous Activity in Embryonic Cardiomyocytes Cultured on Poly(vinyl alcohol)/Bioglass Type 58S Electrospun Scaffolds

Because of the physiological and cardiac changes associated with cardiovascular disease, tissue engineering can potentially restore the biological functions of cardiac tissue through the fabrication of scaffolds. In the present study, hybrid nanofiber scaffolds of poly (vinyl alcohol) (PVA) and bioglass type 58S (58SiO2-33CaO-9P2O5, Bg) were fabricated, and their effect on the spontaneous activity of chick embryonic cardiomyocytes in vitro was determined. PVA/Bg nanofibers were produced by electrospinning and stabilized by chemical crosslinking with glutaraldehyde. The electrospun scaffolds were analyzed to determine their chemical structure, morphology, and thermal transitions. The crosslinked scaffolds were more stable to degradation in water. A Bg concentration of 25% in the hybrid scaffolds improved thermal stability and decreased degradation in water after PVA crosslinking. Cardiomyocytes showed increased adhesion and contractility in cells seeded on hybrid scaffolds with higher Bg concentrations. In addition, the effect of Ca2+ ions released from the bioglass on the contraction patterns of cultured cardiomyocytes was investigated. The results suggest that the scaffolds with 25% Bg led to a uniform beating frequency that resulted in synchronous contraction patterns

Biopelículas a base de pectina de cáscara de naranja (Citrus sinensis): Caracterización física, química y estructural

The orange is one of the crops with the largest plantation in Mexico and growth is expected in the coming years. Derived from agroindustrial activities, orange peel residues are produced, which due to its high pectin content is suitable for obtaining bioplastics, which is the main objective of this work. Pectin extraction was carried out by acid hydrolysis, using 0.1% citric acid and glycerol as plasticizing agent at concentrations of 3%, 4%and 5% to determine the optimal strength and rigidity of the biofilm. Flexible biofilms, free of pores and interstitial spaces, were obtained on the surface of material. The biofilm with a 5% glycerol composition presented uniform characteristics, with better flexibility and physical appearance compared to those of 3%and 4%. Through the FTIR analysis it was determined that the polymer (pectin) showed a characteristic absorption band of the -OH group at 1023 cm-1and for the COOH group at 1732 cm-1characteristic of biodegradable material. According to elementary analysis of the biofilm, we found that composition is C, H, N and S, which make it a non-toxic biodegradable material and environmentallyfriendly.La naranja es uno de los cultivos con mayor plantación en México y se visualiza un crecimiento para los próximos años. Derivado de las actividades de la agroindustria se producen residuos de cáscara de naranja, la cual por su alto contenido de pectina es apropiado para obtener bioplásticos, el cual es el objetivo principal de este trabajo. La extracción de la pectina se realizó mediante hidrólisis ácida, utilizando ácido cítrico al 0,1% y como agente plastificante glicerol a concentraciones de 3%, 4% y 5% para determinar la resistencia y rigidez óptima de la biopelícula. Se obtuvieron biopelículas flexibles, libres de poros y espacios intersticiales en la superficie del material. La biopelícula con composición de glicerol al 5% presentó características uniformes, con mejor flexibilidad y apariencia física en comparación con los de 3% y 4%. Mediante el análisis del FTIR se determinó que el polímero (pectina) mostró una banda característica de absorción del grupo -OH a 3300 cm-1, del grupo C-O a 1023 cm-1 y para el grupo COOH a 1732 cm-1 característica de un material biodegradable. De acuerdo con el análisis elemental de la biopelícula, se encontró que está compuesta por C, H, N y S, lo cual lo hace un material biodegradable no tóxico y amigable con el ambiente