Keynote Talk  - Wednesday, 15 September I 13:35 PM (CEST)

We have investigated the mechanical properties of molecular linkers which mediate cell attachment on biomaterial surfaces by means of single-molecule force spectroscopy. Attachment and spreading of cells on poly(ethylene glycol diacrylate) (PEGDA) hydrogels depend on their mechanical properties, for examples when Young’s modulus E of a hydrogel is varied. A factor of ten in the elastic modulus E corresponded to a factor of five in the effective spring constant k of single crosslinks, indicating a transition in scaling with the mesh size ξ from the macroscopic E ∝ ξ⁻³ to the molecular k ∝ ξ⁻²  [1]. The effective stiffness of single linkers was also measured for a second polymer network based on four-arm star-PEG molecules which interpenetrated the PEGDA hydrogel.

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When linkers are connected to a light-driven molecular motor, an optoregulated force can be applied to cellular receptors [2]. The force is produced by an increasing entanglement of linkers and was quantified by flow force microscopy, where the molecular motors pull tethered beads against the flow in a microfluidic cell.

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[1] A. Colak, B. Li, J. Blass, K. Koynov, A. del Campo, R. Bennewitz, The mechanics of single cross-links which mediate cell attachment at a hydrogel surface, Nanoscale, 11 (2019) 11596-11604.

[2] Y. Zheng, M.K.L. Han, R. Zhao, J. Blass, J. Zhang, D.W. Zhou, J.-R. Colard-Itté, D. Dattler, A. Colak, M. Hoth, A.J. García, B. Qu, R. Bennewitz, N. Giuseppone, A. del Campo, Optoregulated force application to cellular receptors using molecular motors, Nature Communications, accepted (2021).