IntroductionNatural materials as cellulose extracted from wood and chitin extracted from crustaceans shells are promising biocompatible materials for tissue engineering applications. (1, 2) The study focuses on the processing of a novel biobased three -dimensional porous scaffolds for cartilage repair applications. A first phase of the study consists in optimising the composition and the process for suitable mechanical properties in simulated body conditions. In the second phase the biocompatibility of the material and the influence of the presence of chondrocytes extra cellular matrix (ECM) on its mechanical properties will be studied. Materials and methodsThe materials were prepared by freeze drying suspensions of cellulose nanofibers (CNFs) in a matrix of gelatin/chitosan. A single step freeze drying of a solution containing gelatin, CNFs, and chitosan, or a two steps freeze drying of a gelatin and CNFs solutions first, then impregnation with chitosan solution and subsequent freeze drying was performed. Cross-linking is carried out using genipin solution, followed by rinsing, and an additional freeze drying. The prepared materials were characterised by scanning electron microscopy (SEM), compression tests in dry and wet conditions, and Fourier transform Infrared spectroscopy. The porosity is measured by BET method. Cell attachment and proliferation were also evaluated.Results and discussionSEM observations of the freeze dried materials showed homogeneous pore structure. The structure observed shows a macroporous foam with pore size varying between 50 to 200 µm depending on the process and material, with a rough inner surface with nanosized wires formed by CNFs and chitosan. These nanowires are expected to enhance cell attachment and proliferation. The compression tests showed a compression strength of around 0.02 and 0.07 MPa and a compression modulus around 0.3 MPa and 3 MPa according to the initial concentration at 37°C and atmospheric moisture conditions, which is the in the same order of magnitude as natural cartilage i.e. between 0.4 and 0.8MPa according to the literature. (3) Biocompatibility tests also showed positive results and cell growth with the tested materials. Furthermore, the growth of chondrocytes within the samples and the production of ECM are expected to enhance the mechanical properties. (4)ConclusionsFreeze dried micro porous scaffolds of cellulose nanofiber based gelation/ chitosan nanocomposites showed promising mechanical properties and cell growth, with potential for cartilage application.AcknowledgmentsFinancial support from VINNOVA under MNT-ERANET project, n-POSSCOG is acknowledged. EDUCELL, Slovenia is acknowledged for biocompatibility data. References1. Mathew A, Oksman K, Pierron D, Harmad M. Cellulose. 2012 02/01; 19 (1): 139-50.2. Peter M, Ganesh N, Selvamurugan N, Nair SV, Furuike T, Tamura H, et al. Carbohydr Polym. 2010 5/5; 80 (3): 687-94.3. Mansour JM. Kinesiology: the Mechanics and Pathomechanics of Human Movement. 2003 (Ch 5): 66-79.4. Karageorgiou V, Kaplan D. Biomaterials. 2005 9; 26 (27): 5474-91.Proceeding of the MiMe October 8-11, 2013 - Faenza, Italy1st International Conference on Materials in Medicine