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search.filters.applied.f.access: openAccess × Author: Jiang, Qiyang × End date: 2023 × DDC: 600 × Type: Article × WGL Institute: INM ×

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    Elastomeric Optical Waveguides by Extrusion Printing
    (Weinheim : Wiley, 2022) Feng, Jun; Zheng, Yijun; Jiang, Qiyang; Włodarczyk‐Biegun, Małgorzata K.; Pearson, Samuel; del Campo, Aránzazu
    Advances in optogenetics and the increasing use of implantable devices for therapies and health monitoring are driving demand for compliant, biocompatible optical waveguides and scalable methods for their manufacture. Molding, thermal drawing, and dip-coating are the most prevalent approaches in recent literature. Here the authors demonstrate that extrusion printing at room temperature can be used for continuous fabrication of compliant optical waveguides with polydimethylsiloxane (PDMS) core and crosslinked Pluronic F127-diacrylate (Pluronic-DA) cladding. The optical fibers are printed from fluid precursor inks and stabilized by physical interactions and photoinitiated crosslinking in the Pluronic-DA. The printed fibers show optical loss values of 0.13–0.34 dB cm–1 in air and tissue within the wavelength range of 405–520 nm. The fibers have a Young's Modulus (Pluronic cladding) of 150 kPa and can be stretched to more than 5 times their length. The optical loss of the fibers shows little variation with extension. This work demonstrates how printing can simplify the fabrication of compliant and stretchable devices from materials approved for clinical use. These can be of interest for optogenetic or photopharmacology applications in extensible tissues, like muscles or heart.
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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.