Bioactivity and Viscoelastic Characterization of Chitosan/Bioglass 1 Composite Membranes a Sofia G. Caridade,* Esther G. Merino, Nata ´lia M. Alves, Joa ˜o F. Mano 1. Introduction Over the years many efforts have been made to encounter biomaterials for improving life quality, namely in bone regeneration. However, it is well recognized that one biomaterial type does not possess all the mechanical/ chemical properties that are necessary for such applica- tions. Based on the composite character of natural mineralized material, [1] including bone, many strategies have involved the production of composite combining polymers and inorganic elements such as calcium phos- phates or bioactive glasses. The fabrication of composites comprising biodegradable polymers and bioactive glass becomes a suitable option to fulfill the requirements of bioactivity, degradability, adequate biological response, and mechanical strength. [2–4] The use of bioactive ceramics and glasses may be a strategy to provide osteoconductive properties to the composite. For example, bioglass (BG) is a bioactive material in the Na 2 O/CaO/SiO 2 /P 2 O 5 system, which was found to spontaneously bond to living bone without forming a fibrous tissue at the interface [5] and has been used clinically since 1985. BG may be combined with biocompatible and biodegradable polymers in order to produce bioactive composites. [2] The bioactivity of such kind of composites has been monitoring in vitro by following the evolution of the apatite layer that is formed on the surface of the biomaterial after being immersed in simulated body fluid (SBF). Usually the morphological, structural, and chemical characterization of the formed calcified layer is performed at pre-determined time points after immersion in SBF. The description of the biominer- alization process in real time may provide information about the calcification kinetics and mechanism and could describe the evolution of the properties of the biomaterial. However until now, just few studies have followed the biomineralization process in situ. [6–8] Full Paper S. G. Caridade, E. G. Merino, N. M. Alves, J. F. Mano 3B’s Research Group – Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, 4806-909 Taipas, Guimara ˜es, Portugal E-mail: sofia.caridade@dep.uminho.pt S. G. Caridade, E. G. Merino, N. M. Alves, J. F. Mano ICVS/3B’s – PT Government Associate Laboratory, Braga/ Guimara ˜es, Portugal a Supporting information is available from the Wiley Online Library or from the author. Membranes of chitosan (CTS) and composite membranes of CTS with bioglass are prepared by solvent casting. The composite membranes are shown to induce the precipitation of apatite upon immersion in SBF. The biomineralization process is followed by measuring the variation of the viscoelastic properties of the membranes immersed in SBF, both online and offline. Non- conventional DMA is used to measure the change in the storage modulus, E 0 , and the loss factor, tan d, as a function of the immersion in SBF. A simple model is used to estimate the E 0 of the apatite layer formed in vitro that is about 130 MPa. This work shows that innovate mechanical tests can be useful to characterize the mechanical performance of composites under physiological conditions. ß 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim wileyonlinelibrary.com Macromol. Biosci. 2012, DOI: 10.1002/mabi.201200036 1 Early View Publication; these are NOT the final page numbers, use DOI for citation !! R