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Author: Blass, Johanna × DDC: 600 ×

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    Molecular stiffness cues of an interpenetrating network hydrogel for cell adhesion
    (Amsterdam : Elsevier, 2022) Li, Bin; Çolak, Arzu; Blass, Johanna; Han, Mitchell; Zhang, Jingnan; Zheng, Yijun; Jiang, Qiyang; Bennewitz, Roland; del Campo, Aránzazu
    Understanding cells' response to the macroscopic and nanoscale properties of biomaterials requires studies in model systems with the possibility to tailor their mechanical properties and different length scales. Here, we describe an interpenetrating network (IPN) design based on a stiff PEGDA host network interlaced within a soft 4-arm PEG-Maleimide/thiol (guest) network. We quantify the nano- and bulk mechanical behavior of the IPN and the single network hydrogels by single-molecule force spectroscopy and rheological measurements. The IPN presents different mechanical cues at the molecular scale, depending on which network is linked to the probe, but the same mechanical properties at the macroscopic length scale as the individual host network. Cells attached to the interpenetrating (guest) network of the IPN or to the single network (SN) PEGDA hydrogel modified with RGD adhesive ligands showed comparable attachment and spreading areas, but cells attached to the guest network of the IPN, with lower molecular stiffness, showed a larger number and size of focal adhesion complexes and a higher concentration of the Hippo pathway effector Yes-associated protein (YAP) than cells linked to the PEGDA single network. The observations indicate that cell adhesion to the IPN hydrogel through the network with lower molecular stiffness proceeds effectively as if a higher ligand density is offered. We claim that IPNs can be used to decipher how changes in ECM design and connectivity at the local scale affect the fate of cells cultured on biomaterials.
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    Nanomechanics of self-assembled DNA building blocks
    (Cambridge : RSC Publ., 2021) Penth, Michael; Schellnhuber, Kordula; Bennewitz, Roland; Blass, Johanna
    DNA has become a powerful platform to design functional nanodevices. DNA nanodevices are often composed of self-assembled DNA building blocks that differ significantly from the structure of native DNA. In this study, we present Flow Force Microscopy as a massively parallel approach to study the nanomechanics of DNA self-assemblies on the single-molecular level. The high-throughput experiments performed in a simple microfluidic channel enable statistically meaningful studies with nanometer scale precision in a time frame of several minutes. A surprisingly high flexibility was observed for a typical construct used in DNA origami, reflected in a persistence length of 10.2 nm, a factor of five smaller than for native DNA. The enhanced flexibility is attributed to the discontinuous backbone of DNA self-assemblies that facilitate base pair opening by thermal fluctuations at the end of hybridized oligomers. We believe that the results will contribute to the fundamental understanding of DNA nanomechanics and help to improve the design of DNA nanodevices with applications in biological analysis and clinical research.