title: Sea Cucumber-Inspired Autolytic Hydrogels Exhibiting Tunable High Mechanical Performances, Repairability, and Reusability.
abstract: Inspired by stimuli-responsive remarkable changes in consistency (hardening, softening, autolysis) of sea cucumbers, we synthesized a supramolecular polymer(SP) hydrogel directly by photoinitiated aqueous polymerization of N-acryloyl 2-glycine monomer bearing one amide and one carboxyl group on the side chain. The SP hydrogels doped with Ca(2+) demonstrated excellent mechanical properties-high tensile strength (∼1.3 MPa), large stretchability (up to 2300%), high compressive strength (∼10.8 MPa), and good toughness (∼1000 J m(-2)) due to cooperative hydrogen bonding interactions from amide and carboxyl together with Ca(2+) cross-linking. Responding to the change in pH and Ca(2+) concentration, the hydrogels could modulate their network stability and mechanical properties: at pH3.0 and higher Ca(2+) content, the hydrogel formed low swelling network which was stiff and stable; in alkaline or neutral buffer with lower content of or without Ca(2+), the hydrogel formed a highly swollen transient network, which was soft and eventually autolyzed. The reversible multiple noncovalent bonds enabled the hydrogels to achieve thermoplasticity, self-healability, and reusability. Notably, distinct formulations of hydrogels could be welded together under heating to form a gradient hydrogel. In vitro cytotoxicity assay and subcutaneous implantation indicated that the SP hydrogels were biocompatible and autolytic in vivo. The SP hydrogels may find applications as temporary biodevices for intestinal drug delivery or for injectable filling in assisting suturing small vessels.
authors.affiliation: School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University , Tianjin 300072, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Gao
authors.affiliation: School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University , Tianjin 300072, China.
authors.forename: Yinyu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University , Tianjin 300072, China.
authors.forename: Yongmao
authors.initials: Y
authors.lastname: Li
authors.affiliation: School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University , Tianjin 300072, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Xu
authors.affiliation: Department of Chemical Engineering and Materials Science, Wayne State University , Detroit, Michigan 48202, United States.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Cao
authors.affiliation: School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University , Tianjin 300072, China.
authors.forename: Wenguang
authors.initials: W
authors.lastname: Liu
mesh_terms: D000818:Animals; D001329:Autolysis; D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry / Q000627:therapeutic use; D016503:Drug Delivery Systems; D005998:Glycine / Q000138:chemical synthesis / Q000737:chemistry* / Q000627:therapeutic use; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000138:chemical synthesis / Q000737:chemistry* / Q000627:therapeutic use; D006860:Hydrogen Bonding; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry / Q000627:therapeutic use; D012616:Sea Cucumbers / Q000737:chemistry*; D013718:Tensile Strength / Q000187:drug effects; D014867:Water / Q000737:chemistry; D014945:Wound Healing / Q000187:drug effects
chemical_list: D001672:Biocompatible Materials; D011108:Polymers; D014867:Water; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D005998:Glycine
keywords: autolysis; calcium ion; high strength; hydrogel; hydrogen-bonding