title: Cryo-Imaging of Hydrogels Supermolecular Structure.
abstract: Gelatin, derived from collagen, has both the mechanical properties required for tissue growth, as well the functional domains required for cell binding. In its natural state, gelatin derives its properties from a network of structured, intertwined, triple helical chains, which is stabilized by hydrogen bonds at temperatures below 37 °C. The mechanical properties of such a structure can be further controlled by additional enzymatic cross-linking. But, in contrast to simple polymer systems, the response to an imposed deformation is here determined by two competing factors: the establishment of the cross-linked mesh vs. the self-assembly of the fibrils into larger and stronger hierarchical structures. Therefore, properties deduced from the response to measurements such as rheology or swelling, are a combination of these two very different factors, hence a modeling is impossible unless more precise knowledge regarding the internal structure is available. The cryogenic-temperature scanning electron microscopy (cryo-SEM) was adopted to image the fully hydrated gelatin network in which distinct chain folding was observed at low densities, while cross-linked networks were observed at higher densities. Based on these images, a theoretical model which results in good agreement between the mesh sizes of both networks and their mechanical properties was developed.
authors.affiliation: Department of Materials Science and Engineering, Stony Brook University, New York, USA.
authors.forename: Clement
authors.initials: C
authors.lastname: Marmorat
authors.affiliation: Department of Mechanical Engineering, Technion, Haifa, Israel.
authors.forename: Arkadii
authors.initials: A
authors.lastname: Arinstein
authors.affiliation: The Wolfson Department of Chemical Engineering, Technion, Haifa, Israel.
authors.forename: Naama
authors.initials: N
authors.lastname: Koifman
authors.affiliation: The Wolfson Department of Chemical Engineering, Technion, Haifa, Israel.
authors.forename: Yeshayahu
authors.initials: Y
authors.lastname: Talmon
authors.affiliation: Department of Mechanical Engineering, Technion, Haifa, Israel.
authors.forename: Eyal
authors.initials: E
authors.lastname: Zussman
authors.affiliation: Department of Materials Science and Engineering, Stony Brook University, New York, USA.
authors.forename: Miriam
authors.initials: M
authors.lastname: Rafailovich
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry; D020285:Cryoelectron Microscopy; D004548:Elasticity; D005780:Gelatin / Q000737:chemistry* / Q000648:ultrastructure; D020100:Hydrogels / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D012212:Rheology; D013696:Temperature; D011503:Transglutaminases / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D020100:Hydrogels; D005780:Gelatin; D011503:Transglutaminases