Abstract
The aim of this work was the structural investigation of different type I collagen isoforms at atomic and nanoscale, as well as the evaluation of the impact of different fabrication treatments on the structural, mechanical and biological properties of collagen-based films. Raw type-I collagens from bovine hide (Typ-BH, CS, SYM) and equine tendon (TypE, TypCH and OPO) were analyzed. Materials were then used for fabricating air-dried films, obtained by: 1) dissolution in distilled water (HH); 2) dissolution in acidic medium (AA); 3) homogenization of acid solubilized fibers (HOM). Crosslinking treatments (DHT, DHT+EDC) were also adopted and studied. Analysis by Wide Angle (WAXS) and Small Angle (SAXS) X-ray Scattering was carried out at the XMI L@b (CNR-IC-Bari); Fourier Transform-IR and biological analysis was performed at UniSalento. WAXS and SAXS data on raw materials demonstrated the preferential orientation of collagen molecules and the preservation of hierarchical nanoscale architecture in equine tendon-derived collagens, in particular in chemically extracted, while randomly oriented molecules were found in bovine dermis collagens, together with a certain degree of salt contamination. Concerning equine collagen, we found that TypCH structure is influenced by crosslinking procedures at atomic scale, whereas both processing conditions and crosslinking treatments affect TypE collagen structure at atomic and nanoscale. WAXS, SAXS and FT-IR analyses showed that the HOM processing was the one which ensures a high content of structural super-organization of collagen into triple helices and a high crystalline domainof the final material. Crosslinking of the films by DHT/EDC combined treatment was shown to affect their mechanical stiffness, the latter depending on the collagen source and the specific processing conditions.
