Contributed Talk  - Friday, 17 September I 10:00 AM (CEST)

Collagen fibrils (CF) are the main component of the extra cellular matrix (ECM) and provide the biomechanical framework for cell mechanotransduction. Understanding spatiotemporal mechanical properties of individual CFs is crucial for understanding mechanical cues that cells experience. However, state-of-the-art instrumentation only allows for investigation of monotonic tensile properties of individual CFs. We developed a novel instrument for nano-tensile testing of individual CFs. These tests are not limited only to collagen fibrils but can also be applied on tissue-engineered fibers. In short, single magnetic beads are fixated on CFs by help of a custom magnetic tweezer. The magnetic bead along with the CF is lifted by magnetic force and picked-up by a microgripper mounted on a cantilever. We used an error-corrected 2-degrees-of-freedom controller and conducted for the first time true force-controlled tensile tests at 10s of nN resolution. Coupled with AFM nano-indentation tests on the same CFs, we investigate transient and steady-state creep of CFs. The technique has been applied, beyond just collagen fibrils, to investigate viscoelasticity of individual electrospun fibers. Fig.1 Entire experimental process of sample preparation (a)-(d) over AFM contact mode imaging (f) and nano-indentation (g)-(h) to tensile testing of individual CFs (j)-(m).

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