One-Pot Preparation of Collagen Tubes Using Diffusing Gelation

Abstract

One-pot gelation in capillary glass tubes with carbonate-based buffer solution allows the formation of hollow collagen gels (collagen tubes) with an outer diameter of 1 mm or less. The preparation conditions of collagen concentration, buffer concentration, and capillary diameter impacted the ratio and size of the hollow gel and allowed for morphological control of the cavity. The morphology of the hollows suggests that their vacancies are the result of macroscopic phase separation and pinning due to gelation. Mechanical strength measurements of the dried collagen gel tubes demonstrated that the collagen concentration determines their Young’s modulus and maximum stress and that the material is strong enough for practical use. In vitro seeding studies of vascular endothelial cells demonstrated the possible formation of endothelial cells in layers in the gel lumen.

Effect of UV Irradiation of Pre-Gel Solutions on the Formation of Collagen Gel Tubes

“…In our Teflon tube, the buffer solution diffusion as a gelling environment induces a morphology by phase in conjunction with a pinning effect, the entire process of macrophase separation being directed from the top to the bottom end of the tube vertically oriented. The gelated region contracts due to the charge cancelation of the collagen (as a result of the close values of the diffusing environment pH and the isoelectric point of collagen), leading to a space consisting of the aqueous phase close to the Teflon tube wall [ 29 ]. The gelation buffer solution penetrating through this crack leads to gelling and confining the collagen along the wall, lowering the collagen concentration at the center of the Teflon tube to form an aqueous phase.…”

“…This aqueous phase will become a single pore. From previous results, lower concentrations of collagen solution tend to undergo more quickly such a macroscopic phase separation, thus producing a macroscopic pore [ 29 , 31 ]. Non-UV-treated 0.5 wt% collagen solutions may fail to form complete cavities because the concentrated collagen wall is too thin.…”

“…High-density collagen tubes have useful in improving endothelial cell adhesion, and their growth is a potentially promising alternative to vein grafts [ 28 ]. We have found a one-pot method to obtain collagen tube gels [ 29 ] inspired by the multiple micropores formed by collagen gels prepared by anisotropic buffer diffusion [ 30 , 31 ]. These collagen tubes prepared by our method have a diameter of less than 1 mm.…”

Collagen Biocomposites Derived from Fish Waste: Doped and Cross-Linked with Functionalized Fe3O4 Nanoparticles and Their Comparative Studies with a Green Approach

“…Collagen is a structural protein and a biopolymer and considered as a versatile biomaterial due to its better biological properties, which lead to its profound use in biomedical applications . However, there are certain drawbacks of denaturation at temperatures above 37 °C and its inability to dissolve in neutral pH buffers that limit its application in tissue engineering and regenerative medicine. , Specifically, collagen extracted from bovine sources is the most common but increased reports on transmissible diseases in collagen-based products have led to the search for an alternate source. − Moreover, researchers have focused on the sustainable pathways to perform the conversion of bio-waste to value-added products such as catalysts useful for various industrial applications. − Fish scales, which are non-edible bio-waste, produce an obnoxious smell when kept aside for a longer duration and cause environmental pollution. , However, these fish processing wastes can be utilized for various industrial applications. − Additionally, collagen can be derived from fish scales, which become an excellent alternative to the bovine source and are free from transmissible diseases in the developed products. , Despite these benefits, the collagen extracted from fish scales, especially from marine origin has a low denaturation temperature. Also, the high rate of biodegradation and low mechanical stability of collagen are the major problems to be solved for its application. − A simple procedure usually adopted to overcome the above-mentioned problem is to crosslink collagen, which reduces the biodegradation and also enhances the mechanical stability of collagen in the native state.…”

Assembly of Rolled-Up Collagen Constructs on Porous Alumina Textiles

“…So far, collagen was already used as a biocompatible medium for cell encapsulation during bioprinting of tubular constructs, or it was molded into fibrous tubular constructs by vacuum thermoforming . Recently, fibrillar collagen tubes were prepared by gelation with carbonate buffers, and sheets of self-assembled collagen nanofibers and elastin-like proteins were rolled into tubes with a stainless steel mandrel . Despite their diversity, all these processes take advantage of collagen’s inherent ability to assemble into fibers, and combine it with different ways of postprocessing or - shaping.…”