Reversible Stiffening of Biopolymeric Hybrid Networks by Dynamically Switching Cross-Links In Situ

High Resolution Image Download MS PowerPoint Slide Achieving reversible stiffening of biopolymer networks in a controlled manner remains a challenging topic in materials science, especially when trying to assess the following changes in mechanical material properties in real time. To address these challenges, we here utilize a custom-made measurement setup that allows us to manipulate the cross-linking state of alginate-based hydrogels in situ while quantifying the achieved alterations in the viscoelastic response of the biopolymer networks. Interpolymer connections in the biopolymer networks are created by a combination of light-induced, covalent cross-links, ionic cross-links, and DNA-based cross-links, where the latter two can be successfully removed again by employing either chelating agents ( e . g ., ethylenediaminetetraacetic acid and citrate) or suitable displacement DNA strands. In part, this range of the different cross-linking options mentioned is inter alia made possible by incorporating the glycoprotein mucin into the alginate system, which also allows for a range of different starting (∼0.2–400 Pa), intermediate (∼25 Pa–1.6 kPa), and final stiffnesses (∼4 Pa–1.2 kPa) of the mixed hydrogel matrix. At the same time, the presence of mucins (1–4% (w/v)) in the biopolymer mixture enhances the properties of the cytocompatible hydrogel by improving its antibacterial characteristics. Such well-controllable alginate/mucin networks with dynamically switchable mechanical properties will likely find broad applications in cell cultivation studies or tissue engineering applications.