Stabilization of Collagen Fibrils by Gelatin Addition: A Study of Collagen/Gelatin Dense Phases

Abstract

Collagen and its denatured form, gelatin, are biopolymers of fundamental interest in numerous fields ranging from living tissues to biomaterials, food, and cosmetics. This study aims at characterizing mixtures of those biopolymers at high concentrations (up to 100 mg·mL) at which collagen has mesogenic properties. We use a structural approach combining polarization-resolved multiphoton microscopy, polarized light microscopy, magnetic resonance imaging, and transmission electron microscopy to analyze gelatin and collagen/gelatin dense phases in their sol and gel states from the macroscopic to the microscopic scale. We first report the formation of a lyotropic crystal phase of gelatin A and show that gelatin must structure itself in particles to become mesogenic. We demonstrate that mixtures of collagen and gelatin phase segregate, preserving the setting of the pure collagen mesophase at a gelatin ratio of up to 20% and generating a biphasic fractal sample at all tested ratios. Moreover, differential scanning calorimetric analysis shows that each protein separates into two populations. Both populations of gelatins are stabilized by the presence of collagen, whereas only one population of collagen molecules is stabilized by the presence of gelatin, most probably those at the interface of the fibrillated microdomains and of the gelatin phase. Although further studies are needed to fully understand the involved mechanism, these new data should have a direct impact on the bioengineering of those two biopolymers.

Processing of collagen based biomaterials and the resulting materials properties

“…If the gelatine sets, two melting temperatures can be measured. One reflects melting of gelatine gels, the other T D of collagen [238].…”

Native Collagen: Electrospinning of Pure, Cross-Linker-Free, Self-Supported Membrane

“…It builds up efficiently in highly anisotropic fibrillar collagen because of the tight unidirectional alignment (parallel) of peptide bonds along the collagen triple helix and within fibrils both in isolated collagen fibrils , and fibrillary networks . This makes SHG microscopy the gold standard technique for 3D characterization of collagen-rich tissues in ambient conditions and without exogeneous labeling, with a structural specificity that cannot be reached with any other optical and fluorescence microscope, being specific to (i) the native state of collagen (over gelatin) and (ii) the unidirectional alignment of collagen triple helices …”

“…41 This makes SHG microscopy the gold standard technique for 3D characterization of collagen-rich tissues in ambient conditions and without exogeneous labeling, with a structural specificity that cannot be reached with any other optical and fluorescence microscope, being specific to (i) the native state of collagen (over gelatin) and (ii) the unidirectional alignment of collagen triple helices. 42 Measurements on dry membranes showed a high SHG signal (Figure 2A1). This is a proof of the native state of collagen that corresponds to a noncentrosymmetric packing of the triple helices.…”

Injectable hydrogels for tendon and ligament tissue engineering

“…They can also repair T/L tissue to a certain extent. However, collagen hydrogels are easily degraded, gelatin denatures when water swells, and CS possesses low mechanical strength (Abraham, Zuena, Perez‐Ramirez, & Kaplan, 2008; Nettles, Elder, & Gilbert, 2002; Portier et al, 2017). Furthermore, HA, as a natural substance, frequently contains impurities or botulinum toxins, which easily cause allergic reactions and immune responses that are not conducive to tissue repair (Burdick & Prestwich, 2011; Friedman, Mafong, Kauvar, & Geronemus, 2002).…”