Free-standing polyelectrolyte membranes made of chitosan and alginate

Free-standing films have increasing applications in the biomedical field as drug delivery systems for wound healing and tissue engineering. Here, we prepared free-standing membranes by the layer-by-layer assembly of chitosan and alginate, two widely used biomaterials. Our aim was to produce a thick membrane and to study the permeation of model drugs and the adhesion of muscle cells. We first defined the optimal growth conditions in terms of pH and alginate concentration. The membranes could be easily detached from polystyrene or polypropylene substrate without any postprocessing step. The dry thickness was varied over a large range from 4 to 35 μm. A 2-fold swelling was observed by confocal microscopy when they were immersed in PBS. In addition, we quantified the permeation of model drugs (fluorescent dextrans) through the free-standing membrane, which depended on the dextran molecular weight. Finally, we showed that myoblast cells exhibited a preferential adhesion on the alginate-ending membrane as compared to the chitosan-ending membrane or to the substrate side.This work was financially supported by Foundation for Science and Technology (FCT) through the Scholarship SFRH/BD/64601/2009 granted to S.G.C. C.M. is indebted to Grenoble INP for financial support via a postdoctoral fellowship. This work was supported by the European Commission (FP7 Program) via a European Research Council starting grant (BIOMIM, GA 259370 to C.P.). C.P. is also grateful to Institut Universitaire de France and to Grenoble Institute of Technology for financial support. We thank Isabelle Paintrand for her technical help with the confocal apparatus and Patrick Chaudouet for his help with SEM imaging

Utilização de argilas fibrosas e tubulares para a liberação modificadas de fármacos: uma revisão

Nas últimas décadas o uso de argilominerais nas áreas de Ciência e Engenharia de Materiais tem recebido notória atenção para a sua utilização no carreamento de fármacos. Dentre os diversos tipos de argilas, as fibrosas e as tubulares tem sido utilizadas na preparação de bionanocompósitos, devido as suas propriedades inerentes, como exemplo a elevada área superficial. Esta pesquisa visou o levantamento bibliográfico da utilização das argilas tubulares e fibrosas para o carreamento de fármacos. A busca por artigos foi realizado no banco de dados Web of Science, utilizando combinação dos termos: Fibrous Clay and drug delivery, Tubular Clay and drug delivery, Halloysite and drug delivery, Imogolite and drug delivery, Palygoskite and drug delivery e Sepiolite and drug delivery. Foram encontrados o total de 36 artigos durante a pesquisa. Observou-se que a maioria dos artigos utilizam as argilas em combinação com outros materiais (com formação de compósitos e blendas), principalmente polímeros, a fim de expandir as propriedades que melhoram a vetorização de insumos farmacêuticos ativos (IFAs), tais como a modificação do tamanho dos poros, do pH, da energia de ligação entre as moléculas, entre outros. Assim, evidencia-se que o interesse pela utilização das argilas no campo terapêutico tem aumentado, mostrando a relevância de pesquisas na área de medicamentos e materiais