Collagen, the most abundant extracellular matrix protein in animal kingdom belongs to a family of fibrous proteins, which transfer load in tissues and which provide a highly biocompatible environment for cells. This high biocompatibility makes collagen a perfect biomaterial for implantable medical products and scaffolds for in vitro testing systems. To manufacture collagen based solutions, porous sponges, membranes and threads for surgical and dental purposes or cell culture matrices, collagen rich tissues as skin and tendon of mammals are intensively processed by physical and chemical means. Other tissues such as pericardium and intestine are more gently decellularized while maintaining their complex collagenous architectures. Tissue processing technologies are organized as a series of steps, which are combined in different ways to manufacture structurally versatile materials with varying properties in strength, stability against temperature and enzymatic degradation and cellular response. Complex structures are achieved by combined technologies. Different drying techniques are performed with sterilisation steps and the preparation of porous structures simultaneously. Chemical crosslinking is combined with casting steps as spinning, moulding or additive manufacturing techniques. Important progress is expected by using collagen based bio-inks, which can be formed into 3D structures and combined with live cells. This review will give an overview of the technological principles of processing collagen rich tissues down to collagen hydrolysates and the methods to rebuild differently shaped products. The effects of the processing steps on the final materials properties are discussed especially with regard to the thermal and the physical properties and the susceptibility to enzymatic degradation. These properties are key features for biological and clinical application, handling and metabolization.

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Biomimetic mineralization of collagen is an advantageous method to obtain resorbable collagen/hydroxy-apatite composites for application in bone regeneration. In this report, established procedures for mineralization of bovine collagen were adapted to a new promising source of collagen from salmon skin challenged by the low denaturation temperature. Therefore, in the first instance, variation of temperature, collagen concentration, and ionic strength was performed to reveal optimized parameters for fibrillation and simultaneous mineralization of salmon collagen. Porous scaffolds from mineralized salmon collagen were prepared by controlled freeze-drying and chemical cross-linking. FT-IR analysis demonstrated the mineral phase formed during the preparation process to be hydroxyapatite. The scaffolds exhibited interconnecting porosity, were sufficiently stable under cyclic compression, and showed elastic mechanical properties. Human mesenchymal stem cells were able to adhere to the scaffolds, cell number increased during cultivation, and osteogenic differentiation was demonstrated in terms of alkaline phosphatase activity.

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Acid soluble collagen (ASC) and a cattle hide gelatine were analyzed by size exclusion chromatography (SEC) coupled with multi angle light scattering (MALS). The SEC system was calibrated with ASC and its cyan bromide cleavage products. The accuracy of calibration was confirmed by MALS by measuring the mass-average molar masses (Mw). ASC acted as a mixture of two polymer standards of Mw = 90 and 180 kg/mol, respectively. The elution behavior of the gelatine in SEC-MALS was similar to that of ASC. Therefore, the determination of the molar mass distribution of this gelatine was possible either by SEC, using a calibration curve, or by MALS by direct measurement of Mw. According to the scaling law (1/2) = KMalpha, alpha = 0.78 was determined for the gelatine. This alpha could reflect a structure in solution, which is more similar to an ellipsoid than to a random coil.

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This article describes a technology for the thermoplastic treatment of collagen. Based on limed, untanned cattle pelts a fine powder, termed Thermoplastic Collagen (TC) is produced, which can be processed using conventional thermoplastic techniques. Central step in the production of TC is the partial denaturation of collagen, which was achieved by four different methods. Extrusion of TC at temperatures below 100°C is possible after addition of 30–60% water as plasticizer. In order to maintain permanent flexibility and reduce tackiness, glycerol and stearic acid are used as additives. Shear and elongational viscosities of TC‐water‐mixtures decrease with the shear rate which is consistent with the behavior of thermoplastic materials. The power law can be applied, yielding power law indices of 0.15–0.35. The viscosities are more distinctly influenced by raw material and water content than by temperature or glycerol content. Material properties of the extrudates are described and compared with the starting material. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013