Investigations of Processing–Induced Structural Changes in Horse Type-I Collagen at Sub and Supramolecular Levels

Abstract

The aim of this work is to evaluate the effects of different extraction and material processing protocols on the collagen structure and hierarchical organization of equine tendons. Wide and Small Angle X-ray Scattering investigations on raw powders and thin films revealed that not only the extraction and purification treatments, but also the processing conditions may affect the extent of the protein crystalline domain and induce a nanoscale “shield effect.” This is due to the supramolecular fiber organization, which protects the atomic scale structure from the modifications that occur during fabrication protocols. Moreover, X-ray analyses and Fourier Transform Infrared spectroscopy performed on the biomaterial sheds light on the relationship between processing conditions, triple helical content and the organization in atomic and nanoscale domains. It was found that the mechanical homogenization of the slurry in acidic solution is a treatment that ensures a high content of super-organization of collagen into triple helices and a lower crystalline domain in the material. Finally, mechanical tensile tests were carried out, proving that the acidic solution is the condition which most enhances both mechanical stiffness and supramolecular fiber organization of the films.

Wide Angle X-Ray Scattering to Study the Atomic Structure of Polymeric Fibers

“…The pattern is centered, calibrated and integrated along the meridional and equatorial directions, and the corresponding 1D WAXS profiles are displayed in the same figure (yellow curves). As shown in Table 1, as well as in our recent WAXS studies performed on type I collagen [44,45], we found a meridional diffraction peak at q1 = 2.22 ± 0.075 Å −1 (marked as 1 in Figure 3a), corresponding to the distance between amino acidic residues along the c-axis of the helix (d = 2.8 ± 0.1 Å, helical axial periodicity). A further diffraction signal was found orthogonally to it: the equatorial peak at q2 = 0.6 ± 0.05 Å −1 (marked as 2 in Figure 3a), corresponding to the lateral packing (d = 10.65 ± 1 Å) of triple helices which varies with the hydration state of the material.…”

“…The type I collagen here analyzed was derived by commercially available raw flakes extracted from equine tendons through a chemical protocol. The protein was provided by Typeone Srl (Lecce, Italy) [44,45].…”

Collagen/PCL Nanofibers Electrospun in Green Solvent by DOE Assisted Process. An Insight into Collagen Contribution

“…To better investigate this aspect for the here selected electrospinning conditions, WAXS spectra were recorded for native freeze-dried collagen, before and after acidic dissolution in acetic acid 90% v/v ( Figure 7 ), after electrospinning treatment ( Figure 8 A), and in blend with PCL in collagen/PCL nanofibers ( Figure 8 B,C). Indeed, in recent works [ 42 , 43 , 44 ] the successful applicability of this technique on multiscale structural characterization of collagen, starting from raw macromolecules to the final biomaterials, was demonstrated.…”

Sea Cucumber Derived Type I Collagen: A Comprehensive Review

“…Different lengths of the helix, presence of non-helical components, interruptions in the helix, variations in the assembly of the basic polypeptide chains, and differences in the terminations of the helical domain directly lead to distinct types of collagens. Its general groups include fibrillar collagens, FACIT (Fibril Associated Collagens with Interrupted Triple Helices), FACIT-like collagen, beaded filament collagen, basement membrane collagen, short-chain collagen, transmembrane collagen, and unclassified collagen [ 29 , 33 ]. The length of the helix and portions of non-helical components are different depending on the type of collagen.…”

“…In addition, due to various religious constraints, porcine or mammalian collagen for the development of kosher and halal products is limited [ 10 , 21 , 22 ]. Apart from the widely used species, several studies ( Table 2 ) have extracted collagen from chicken [ 43 ], kangaroo tail [ 44 ], rat tail tendon [ 45 ], duck feet [ 46 ], equine tendon [ 33 ], alligators bone [ 47 ], birds’ feet [ 48 , 49 , 50 ], sheep tendon [ 51 , 52 , 53 , 54 , 55 ], and frog skin [ 56 ], while some studies have focused on using recombinant human collagen [ 20 ]. The high pathological risk for transmitted diseases and complicated extraction process have limited the applicability of using land animal collagen and created a growing concern towards finding alternative sources for collagen.…”