Nanocompósitos de celulose bacteriana/poli(N-metacriloil glicina) preparados por polimerização in situ para aplicações biomédicas

摘要

Cellulose is the most abundant polysaccharide on earth, it is the main structural component of plant cell walls. However, it is also produced by bacteria in a purer form called bacterial cellulose (BC). BC is well known and mainly used in several field for its peculiar 3D network that confers to it outstanding properties such as water high holding capacity, high porosity and excellent mechanical properties. BC is also biodegradable and biocompatible. Among the different fields of application, BC is greatly used, in its pure form or in the form of nanocomposites, in the biomedical field, as artificial blood vessels, controlled drug delivery systems, and in tissue engineering, etc.The present study reports the development of new nanocomposites made from BC and an acrylate polymer namely the poly(N-methacryloyl glycine) (PMGly) through an in situ free radical polymerization using N,N-methylenebis(acrylamide) (MBA) as cross linker agent. Several nanocomposites with different amounts of polymer and BC were prepared and characterized. The obtained nanocomposites displayed improved mechanical properties, thermal stability and crystallinity when compared to the homopolymer. Moreover, their cytotoxicity (MTT tests) in regard to HaCaT skin cells was also evaluated, and the results showed that the new nanocomposites were not cytotoxic until 48 hours of exposure. Finally, two different potential applications were tested for these materials, namely as systems for drug release and as scaffolds for bone regeneration. First, the membranes were tested as drug delivery system for diclofenac. The impregnation of the drug into the membrane was successfully assessed and the drug dissolution was studied for different pH values (pH 7.4 and 2.1) at 37 ºC during 24 hours. However, the drug release was always accompanied by polymer dissolution. Secondly, the membranes were immersed in a simulated body solution in order to grow hydroxyapatite particles on their surface, aiming an application in bone tissue engineering. However, this growth wasn’t detected by XRD and SEM analysis.