RESUMO
Cartilage is a structural tissue with unique mechanical properties deriving from its electrically-charged porous structure. Traditional three-dimensional environments for the culture of cells fail to display the complex physical response displayed by the natural tissue. In this work, the reproduction of the charged environment found in cartilage is achieved using polyelectrolyte hydrogels based on polyvinyl alcohol and polyacrylic acid. The mechanical response and morphology of microporous physically-crosslinked cryogels are compared to those of heat-treated chemical gels made from the same polymers, as a result of pH-dependent swelling. In contrast to the heat-treated chemically-crosslinked gels, the elastic modulus of the physical cryogels was found to increase with charge activation and swelling, explained by the occurrence of electrostatic stiffening of the polymer chains at large charge densities. At the same time, the permeability of both materials to fluid flow was impaired by the presence of electric charges. This cartilage-like mechanical behavior displayed by responsive cryogels can be reproduced in other polyelectrolyte hydrogel systems to fabricate biomimetic cellular scaffolds for the repair of the tissue.
Assuntos
Cartilagem Articular/fisiologia , Criogéis/química , Resinas Acrílicas/química , Força Compressiva , Módulo de Elasticidade , Hidrogéis/química , Concentração de Íons de Hidrogênio , Microscopia de Força Atômica , Microscopia Confocal , Permeabilidade , Polieletrólitos/química , Álcool de Polivinil/química , Porosidade , Eletricidade Estática , TemperaturaRESUMO
This study presents results obtained after implantation of 25 diffractive multifocal intraocular lenses. The follow-up ranged from six to 12 months. Visual acuity for distance without correction was 0.5 or better in 72% of cases; for near, it was J1 to J3 in 84% of cases. Slight decentration of the lens and pupil size did not affect visual acuity.
