Glassy state of native collagen fibril?

• Published in: Europhysics letters Vol. 95; no. 2; p. 23001
• Main Authors: Gevorkian, S. G, Allahverdyan, A. E, Gevorgyan, D. S, Hu, C.-K
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01-07-2011; EPS, SIF, EDP Sciences and IOP Publishing
• Subjects: 05.20.Dd; 36.20.-r; 36.20.Ey; Collagens; Glassy; Heating; Indication; Internal friction; Modulus of elasticity; Quasicrystals; Softening
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/0295-5075/95/23001

Our micromechanical experiments show that viscoelastic features of type-I collagen fibril at physiological temperatures display essential dependence on the frequency and speed of heating. For temperatures of 20–30 °C the internal friction has a sharp maximum for a frequency less than 2 kHz. Upon heating the internal friction displays a peak at a temperature Tsoft(v) that essentially depends on the speed of heating v: Tsoft≈70 °C for v=1 °C/min, and Tsoft≈25 °C for v=0.1 °C/min. At the same temperature Tsoft(v) Young's modulus passes through a minimum. All these effects are specific for the native state of the fibril and disappear after heat-denaturation. Taken together with the known facts that the fibril is axially ordered as quasicrystal, but disordered laterally, we interpret our findings as indications of a glassy state, where Tsoft is the softening transition.