Collagen, the major component of the extracellular matrix, key factor of tissue architecture, provides tensile strength, cell-matrix and matrix-matrix interactions. 2-D and 3-D collagen constructs are widely used as tissue scaffolds in a variety of biomedical applications. Here we synthetized scaffolds structured as thin films (30-50 μm in thickness) and we characterized them from a structural and functional point of view. Type I collagen isolated from bovine tendon (Sigma Aldrich) was suspended at 0.5% w/v in dilute hydrochloric acid (pH=3-3.2) by mixing at 15,000 rpm in an overhead blender, under proper refrigeration. After degassing via centrifugation, the slurry was cast in polystyrene molds and dried for at least 48 hours at room temperature, to obtain dry collagen films. In order to modulate their mechanical properties and degradation rate, the samples were subjected to two different crosslinking treatments, either dehydrothermal crosslinking (DHT) only, at 121°C for 24 hours, or DHT treatment combined with chemical crosslinking by means of a water soluble carbodiimide (DHT/EDC). First, atomic force microscopy measurements of the films showed differences in structure reticulation. As expected, the DHT/EDC scaffold surface presented a more intricate ﬁbrillar assembly, and a lower swelling degree after the first 24 hours (about 30% less). Once integrated into appositely fabricated polymeric devices, DHT and DHT/EDC scaffolds were tested in cellular oxygen consumption and proliferation assays. Fibroblasts, seeded at the same densities on both DHT and DHT/EDC substrates, displayed different oxygen consumption rate (OCR) within 48 hours, reflecting dissimilarities in terms of structural organization and oxygen diffusion efficiency. The obtained results could represent a useful approach to indicate some culture parameters, such as cell-seeding optimal values for the feasibility of tissue models, depending on scaffold structure design.
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