Abstract

Collagen is an abundant component in the human body and plays a fundamental role in the integrity and function of various tissues, including skin, bones, joints, and connective tissues. This natural polymer also contributes to physiological balance and individual health. Within this context, this article reviews the structure of collagen, describing intrinsic characteristics that range from its molecular composition to its organization into bundles. ….  For this review, searches were performed in PubMed, Scopus, and Web of Sciences. ….. Analysis of the properties of collagen revealed its key importance for the design of bioactive materials in regenerative applications.

Materials in the form of membranes and films

Materials in the form of membranes and films act as mechanical barriers that contribute to microbial control, preventing bacterial invasion and reducing fluid loss through evaporation. This enables gas exchange and helps maintain a moist environment, thus contributing to wound healing by promoting cell adhesion, proliferation, and differentiation at the site.

Different fabrication systems have been developed for the production of these materials. In fact, the principles of extrusion used for fiber fabrication can also be applied to the production of films and membranes.²¹ According to Ramshaw and Glattauer, membranes can be produced using approaches such as the compression of a foam or sponge of soluble or fibrous collagen. The method applied can influence the permeability of the material and fiber density. Depending on the purpose, the material should not facilitate cell migration.

Another method is solvent evaporation (casting), in which a polymer solution is poured onto and solidified on a flat surface, thereby forming a continuous membrane. Phase inversion techniques such as immersion precipitation can also create porous membranes for nutrient and gas exchange. However, lyophilization is the main procedure used in membrane processing. For example, intrinsic variation in the lyophilization process exerts a critical impact on the exact regulation of material morphology, that is, variations in the final result of the material are not limited to the techniques employed but also to the intrinsic conditions of the process. Differences in evaporation rates during lyophilization can cause significant changes in the structure and uniformity of the material, directly influencing the formation of nanostructures and layer integrity. The understanding and control of these variables are therefore essential to optimize the desired morphology and to ensure the consistency and quality of the material produced.

These examples illustrate the diversity of approaches available for engineering films and membranes, each with their own specific advantages depending on the desired application. Collagen-based materials also permit the incorporation of growth factors, antimicrobial agents, and other biomolecules that accelerate regeneration and improve tissue quality. Within this context, collagen membranes are frequently used for the treatment of skin wounds, exhibiting reabsorption capacity at a rate that follows tissue growth. A notable example of the application of membrane-like biomaterials is the human amniotic membrane. Used for the treatment of skin and ocular wounds, this membrane has shown favorable results in terms of healing and pain relief in complex wounds. The human amniotic membrane is characterized by low immunogenicity and is rich in growth factors and ECM proteins, which are essential for promoting tissue regeneration and for accelerating the healing process. Gorell et al. evaluated the effect of Helicoll is a type I collagen skin substitute, for the treatment of chronic wounds in patients with recessive dystrophic EB. The results showed that Helicoll significantly improved healing of the treated wounds, with three patients achieving complete re-epithelialization, in addition to significantly decreasing pruritus and pain scores.

Reference

59. Gorell ES, Leung TH, Khuu P, et al. Purified type I collagen wound matrix improves chronic wound healing in patients with recessive dystrophic epidermolysis bullosa. Pediatr Dermatol2015; 32(2): 220–225.