SKM 2021 – scientific programme
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BP: Fachverband Biologische Physik
BP 4: Posters Biological Physics
BP 4.2: Poster
Thursday, September 30, 2021, 11:15–12:15, P
Nonlinear viscoelastic behavior and hysteresis in hydrated collagen fibrils — •Martin Dehnert, Paul Zech, and Robert Magerle — Fakultät für Naturwissenschaften, Technische Universität Chemnitz, Germany
We study the nanomechanical properties of hydrated collagen fibrils with AFM-based nanoindentation measurements. Force–distance (FD) data measured with tip velocities < 1 µm/s and different indentation protocols (force relaxation, creep, and cyclic loading) display nonlinear viscoelastic and elastoplastic behavior: (a) stress relaxation with a time constant τR ∼ 0.1 s, (b) creep with a time constant τC ∼ 5 s, and (c) approximately rate-independent hysteretic behavior with return point memory at intermediate time scales. The main cause of the hysteresis is the elastoplastic deformation of collagen fibrils in the leathery regime. We explore the variations of these nanomechanical properties in sets of unfixed hydrated collagen fibrils isolated from native chicken achilles tendon and compare it with collagen fibrils embedded in the natural tendon. AFM imaging in air with controlled humidity preserves the tissue’s native water content and allows for high-resolution imaging the assembly of collagen fibrils beneath an approximately 5 to 10-nm-thick layer of the fluid components of the interfibrillar matrix. This sheds new light on the role of interfibrillar bonds, the mechanical properties of the interfibrillar matrix, and the biomechanics of native tendon.