Preparação, caracterização morfologica e aplicações de hidrogeis de P(N-isopropilacrilamida-co-acido acrilico) / Preparation, morphological characterization of P(NIPAAM-CO-AAc) hydrogels

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Hydrogels composed of polymeric networks are of great interest as biomaterials. In this work hydrogels of poly(N-isopropilacrilamide) copolimerized with acrylic acid (P(NIPAAm-co-AAc)) and cross-linked with metilene-bisacrilamide (MBAAm) at different cross-linking degrees, interpenetrated (IPNs) and semi-IPNs with PVA. The presence of AAc allowed increasing the lower critical solution temperature (LCST) to 37° C. It was observed that the mechanical properties of the hydrogels are significantly improved with the presence of PVA in the polymeric network and with the increase in the cross-linking degree. It was observed that an increase from 3 to 5% in the crosslinking degree leads to a change in the pore morphology of the hydrogels from spherical to tubular and that the diffusion of methylene blue from the hydrogels with tubular pores is increased when the main axis of the pores are parallel oriented to the flow of the solute. The diffusion of S-nitrosothiols showed that the increase in the cross-linking degree from as well as the reduction in temperature from 37 to 25° C, leads to a reduction in the diffusion rates of S-nitrosoglutathione (GSNO) and S-nitroso-N-acetylcysteine (SNAC) incorporated in the hydrogels and that both the absorption and diffusion of these solutes depend on the interactions between their net electrical charge and that of the polymeric matrix at a given pH. GSNO and SNAC containing hydrogels were able to cause local vasodilation in the skin in topical applications through their actions as nitric oxide (NO) donors. The more intense and less lasting vasodilation action of SNAC, compared to GSNO was correlated to its higher diffusion coefficient in the hydrogel matrix. Application of the hydrogel bound through fibrin adhesive in an animal model of gastroschisis, provided an effective protection of herniated bowel, with reduction of inflammation.

ASSUNTO(S)

hydrogel morphology s-nitrosotiois s-nitrosothiols hidrogel morfologia

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