Insight into the rheological behaviors of a polyanionic collagen fabricated with poly(γ‐glutamic acid)‐NHS ester

Abstract

The rheological behaviors of a polyanionic collagen, fabricated using poly(γ -glutamic acid)-N-hydroxysuccinimide (γ -PGA-NHS) as a novel modifier, were investigated in this study. It was found that both of the native and modified collagen solutions were pseudoplastic fluids, as shown from the steady-shear tests. While the storage modulus and loss modulus of collagen increased with increasing the amount of γ -PGA-NHS, or with increasing the degree of esterification of γ -PGA-NHS; meanwhile, the dynamic denaturation temperature determined by dynamic temperature sweep was also increased, indicating an improved thermal stability of collagen solution modified by γ -PGA-NHS. The creeprecovery measurements showed that the resistance to deformation was enhanced for modified collagen, probably due to the cross-linking occurred between the ε-amino groups of collagen molecules and α-COOH groups of γ -PGA-NHS, as well as the electrostatic interaction and hydrogen-bond interactions between the two molecules. Furthermore, the aggregation of collagen fibers was promoted due to these interactions between collagen and γ -PGA-NHS as observed by atomic force morphology. In addition, the modified collagen exhibited good cytocompatibility as demonstrated by cell growth culturing. The obtained information was expected to give valuable clues to the design and fabrication of controlled stable collagen-based products for applications in various biomedical fields.

Effect of pH on the Structure, Functional Properties and Rheological Properties of Collagen from Greenfin Horse-Faced Filefish (Thamnaconus septentrionalis) Skin

“…When the pH (2,4,6) is lower than the pI, the dominant role of elastic behaviour gradually decreases, viscous behaviour becomes dominant, and the solution exhibits liquid-like behaviour. The unique viscoelastic properties of collagen facilitate its use in tissue engineering and drug delivery applications, such as injectable biomaterials and wound dressings [43][44][45]. The complex viscosity of the pH-treated collagen solutions decreased with increasing sweep frequency (Figure 8c), suggesting that all pH-treated collagen solutions exhibited non-Newtonian shear thinning behaviour, which is generally suitable for practical applications, such as those requiring syringeability and easy spreadability [46].…”