title: Double-network acrylamide hydrogel compositions adapted to achieve cartilage-like dynamic stiffness.
abstract: Since articular cartilage has a limited potential for spontaneous healing, various techniques are employed to repair cartilage lesions. Acrylate-based double-network (DN) hydrogels containing ~90% water have shown promising properties as repair materials for skeletal system soft tissues. Although their mechanical properties approach those of native cartilage, the critical factor-stiffness-of DN-gels does not equal the stiffness of articular cartilage. This study investigated whether revised PAMPS/PAAm compositions with lower water content result in stiffness parameters closer to cartilage. DN-gels containing 61, 86 and 90% water were evaluated using two non-destructive, mm-scale indentation test modes: fast-impact (FI) and slow-sinusoidal (SS) deformation. Deformation resistance (dynamic modulus) and energy handling (loss angle) were determined. The dynamic modulus increased with decreasing water content in both testing modes. In the 61% water DN-gel, the modulus resembled that of cartilage (FI-mode: DN-gel = 12, cartilage = 17; SS-mode: DN-gel = 4, cartilage = 1.7 MPa). Loss angle increased with decreasing water content in fast-impact, but not in slow-sinusoidal deformation. However, loss angle was still much lower than cartilage (FI: DN-gel = 5, cartilage = 11; SS: DN-gel = 10, cartilage = 32°), indicating somewhat less ability to dissipate energy. Overall, results show that it is possible to adapt DN-gel composition to produce dynamic stiffness properties close to normal articular cartilage.
authors.affiliation: Laboratory of Biomechanics and Biocalorimetry (LOB2), Biozentrum/Pharmazentrum, Faculty of Medicine, University of Basel, Klingelbergstrasse 50-70, 4056, Basel, Switzerland. sarah.ronken@gmail.com
authors.forename: S
authors.initials: S
authors.lastname: Ronken
authors.forename: D
authors.initials: D
authors.lastname: Wirz
authors.forename: A U
authors.initials: AU
authors.lastname: Daniels
authors.forename: T
authors.initials: T
authors.lastname: Kurokawa
authors.forename: J P
authors.initials: JP
authors.lastname: Gong
authors.forename: M P
authors.initials: MP
authors.lastname: Arnold
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry* / Q000494:pharmacology*; D000818:Animals; D001696:Biomechanical Phenomena / Q000187:drug effects; D002356:Cartilage / Q000187:drug effects* / Q000502:physiology*; D055119:Elastic Modulus / Q000187:drug effects; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry* / Q000494:pharmacology*; D011108:Polymers / Q000737:chemistry; D013451:Sulfonic Acids / Q000737:chemistry; D034421:Sus scrofa; D014867:Water / Q000737:chemistry; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D011108:Polymers; D013451:Sulfonic Acids; D014867:Water; D000099166:Polyacrylamides; C077118:poly(2-acrylamido-2-methyl-1-propanesulfonic acid)