Creation of Chemically Tri-Layered Collagen Crosslinked Membranes and Their Comparison with Ionically Tri-Layered Chitosan Crosslinked Membranes to Study Human Skin Properties.

In 2009, a new European regulation came into force that forbade the use of animals in the cosmetics industry. As a result, new alternatives were sought, taking into account the new ethical considerations. The main objective of this article is to continue a line of research that aims to build a physical model of skin from a biomaterial scaffold composed of collagen, chitosan or a combination to investigate whether they offer similar behavior to human skin. Collagen, the major component in the dermis, was crosslinked with glutaraldehyde (GTA) to develop three formulations for studying some properties of the skin through rheological tests like swelling index, elasticity or water loss. In addition, this article makes a comparison with the results obtained in the previous article where the membranes were made of chitosan and tripolyphosphate (TPP). The results obtained highlight that the tri-layered membranes scaffold better than the mono-layered ones to increase the elastic modulus (G') and the permeability. Furthermore, they offer a protective effect against water loss compared to mono-layered membranes. As regards chitosan membranes, these have a higher G' modulus than collagen membranes when the degree of deacetylation (DDA) is 85%. However, collagen membranes are more elastic when the DDA of chitosan is 76%, and their linear viscoelastic limit (LVL) doubles that of chitosan membranes, both for the degree of acetylation of 76 and 85%.

Study of Elastin, Hydrolyzed Collagen and Collagen-like Products in a Tri-Layered Chitosan Membrane to Test Anti-Aging Skin Properties.

The use of animal testing in the cosmetic industry is already prohibited in more than 40 countries, including those of the EU. The pressure for it to be banned worldwide in the future is increasing, so the need for animal alternatives is of great interest today. In addition, using animals and humans in scientific research is ethically reprehensible. This study aimed to prove some of the anti-aging properties of elastin (EL), hydrolyzed collagen (HC), and two vegan collagen-like products (Veg Col) in a tri-layered chitosan membrane that was ionically crosslinked with sodium tripolyphosphate (TPP). In the first approach, as a way of representing different layers of a biological system, such as the epidermis and the two dermis sublayers, EL, HC, or Veg Col were independently introduced into the two inner layers (2L(i+b)). Their effects were compared with those of their introduction into three layers (3L). Different experiments were performed on the membrane to test its elasticity, hydration, moisture retention, and pore reduction at different concentrations of EL, HC, and Veg Col, and the results were normalized vs. a blank membrane. This new alternative to animal or human testing can be suitable for proving certain efficacy claims for active ingredients or products in the pharmaceutical, nutritional, and cosmetic fields.

Creation of Ionically Crosslinked Tri-Layered Chitosan Membranes to Simulate Different Human Skin Properties.

In 2023, new legislation will ban the use of animals in the cosmetic industry worldwide. This fact, together with ethical considerations concerning the use of animals or humans in scientific research, highlights the need to propose new alternatives for replacing their use. The aim of this study is to create a tri-layered chitosan membrane ionically crosslinked with sodium tripolyphosphate (TPP) in order to simulate the number of layers in human skin. The current article highlights the creation of a membrane where pores were induced by a novel method. Swelling index, pore creation, and mechanical property measurements revealed that the swelling index of chitosan membranes decreased and, their pore formation and elasticity increased with an increase in the Deacetylation Grade (DDA). Additionally, the results demonstrate that chitosan's origin can influence the elastic modulus value and reproducibility, with higher values being obtained with seashell than snow crab or shrimp shells. Furthermore, the data show that the addition of each layer, until reaching three layers, increases the elastic modulus. Moreover, if layers are crosslinked, the elastic modulus increases to a much greater extent. The characterization of three kinds of chitosan membranes was performed to find the most suitable material for studying different human skin properties.