RESUMO
The objective of this work was to correlate the physical and chemical properties of chitosan/poly(vinyl alcohol)/genipin (CS/PVA/GEN) and chitosan/poly(vinyl alcohol)/glutaraldehyde (CS/PVA/GA) hydrogels with their structural and mechanical responses. In addition, their molecular structures were determined and confirmed using FTIR spectroscopy. The results indicated that the hybrid hydrogels crosslinked with genipin showed similar crystallinity, thermal properties, elongation ratio and structural parameters as those crosslinked with glutaraldehyde. However, it was found that the elastic moduli of the two hybrid hydrogels were slightly different: 2.82±0.33MPa and 2.08±0.11MPa for GA and GEN, respectively. Although the hybrid hydrogels crosslinked with GEN presented a lower elastic modulus, the main advantage is that GEN is five to ten thousand times less cytotoxic than GA. This means that the structural and mechanical properties of hybrid hydrogels crosslinked with GEN can easily be tuned and could have potential applications in the tissue engineering, regenerative medicine, food, agriculture and environmental industries.
Assuntos
Produtos Biológicos/química , Quitosana/química , Hidrogéis/química , Fenômenos Mecânicos , Materiais Biocompatíveis/química , Glutaral/química , Iridoides/química , Álcool de Polivinil/química , Temperatura , Resistência à TraçãoRESUMO
We demonstrate the use of random laser emission for mechanical testing of bovine pericardium. An apparatus designed for tensile tests of soft and thin materials, incorporating optical and mechanical devices, allows for obtaining the mechanical behavior of the tissue samples. Using both, digital image correlation (DIC) and random laser emission analysis, the apparatus provides information regarding the response of the bovine pericardium under different stress levels. Our results show that changes in the spectral features of the random laser correlate well to the mechanical response obtained with conventional uniaxial tensile analysis coupled with DIC. Furthermore, parameters such as the shear and Young moduli are consistent with values reported previously and obtained with other techniques. Changes at the microstructural level of the tissue may thus be evaluated through spectral analysis of the random laser emission from biological samples.
Assuntos
Lasers , Fenômenos Mecânicos , Pericárdio , Animais , Fenômenos Biomecânicos , Bovinos , Estresse MecânicoRESUMO
En la actualidad el desarrollo de prótesis presenta problemas que aún no se han solucionado por completo. A pesar de que se han desarrollado varios estudios enfocados a evaluar el funcionamiento de las prótesis, los trabajos que se presentan en la literatura se realizan con suposiciones de carga, de materiales, e incluso se practican bajo condiciones estáticas. La técnica de correlación de imágenes digitales ha sido útil en diversas aplicaciones, pero ha sido poco explorada en el ambiente de las prótesis. En este trabajo se presenta una técnica capaz de medir la deformación real en sistemas protésicos de pacientes amputados, bajo condiciones de carga y postura reales. Empleando el método de correlación de imágenes digitales es posible evaluar la prótesis del paciente sin necesidad de instrumentarla o modificarla. Además es posible conocer los principales puntos de deformación sin tener que fracturar la pieza. Con esta técnica es posible medir las principales zonas de deformación de un sistema protésico, con la ventaja de que la evaluación se pueden llevar a cabo aplicando cargas y posturas reales de un paciente en un análisis dinámico.
At present, the development of prostheses presents problems that have yet to be completely solved. Despite that various studies have been developed to evaluate the functioning of these prostheses, the works presented in the literature are conducted with suppositions of burden, of materials, and are even practiced under static conditions. The technique of Digital image correlation (DIC) has been useful in diverse applications, but has been scarcely explored in the ambience of prostheses. In this work, we present a technique capable of measuring the real deformation of prosthetic systems in patients with amputations, under real conditions of load and posture. Employing the DIC method, it is possible to evaluate a patient?s prosthesis without the need for instrumenting or modifying it. In addition, it is possible to know the main points of deformation without having to ultimate load the piece. With this technique, it is possible to measure the prosthetic system?s main deformation zones, with the advantage that evaluation can be performed applying the real loads and postures of a patient in a dynamic analysis.
RESUMO
The micromechanical behavior of lyophilized glutaraldehyde bovine pericardium undergoing uniaxial tension was studied by digital image correlation. The experiments were conducted simultaneously at macromechanical and micromechanical levels, to correlate the mechanical response of this biomaterial at different scales. From the experiments, displacement and force data were acquired; in addition, an image sequence of each sample surface was registered with a high-definition camera. With the images, it was possible to obtain the vector displacement field between pairs of images and then the in-plane strain was calculated. The secant and final moduli of this material were obtained at macromechanical and micromechanical levels. A good agreement between the micro and macro moduli was observed. This analysis is a useful alternative technique for studying this biomaterial when local properties are needed for medical applications.