title: Increasing mechanical strength of gelatin hydrogels by divalent metal ion removal.
abstract: The usage of gelatin hydrogel is limited due to its instability and poor mechanical properties, especially under physiological conditions. Divalent metal ions present in gelatin such as Ca(2+) and Fe(2+) play important roles in the gelatin molecule interactions. The objective of this study was to determine the impact of divalent ion removal on the stability and mechanical properties of gelatin gels with and without chemical crosslinking. The gelatin solution was purified by Chelex resin to replace divalent metal ions with sodium ions. The gel was then chemically crosslinked by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). Results showed that the removal of divalent metal ions significantly impacted the formation of the gelatin network. The purified gelatin hydrogels had less interactions between gelatin molecules and form larger-pore network which enabled EDC to penetrate and crosslink the gel more efficiently. The crosslinked purified gels showed small swelling ratio, higher crosslinking density and dramatically increased storage and loss moduli. The removal of divalent ions is a simple yet effective method that can significantly improve the stability and strength of gelatin hydrogels. The in vitro cell culture demonstrated that the purified gelatin maintained its ability to support cell attachment and spreading.
authors.affiliation: Stem Cell and Tissue Engineering Lab, Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931.
authors.forename: Qi
authors.initials: Q
authors.lastname: Xing
authors.affiliation: Stem Cell and Tissue Engineering Lab, Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931.
authors.forename: Keegan
authors.initials: K
authors.lastname: Yates
authors.affiliation: Stem Cell and Tissue Engineering Lab, Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931.
authors.forename: Caleb
authors.initials: C
authors.lastname: Vogt
authors.affiliation: Stem Cell and Tissue Engineering Lab, Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931.
authors.forename: Zichen
authors.initials: Z
authors.lastname: Qian
authors.affiliation: Polymer and Biomaterial Lab, Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931.
authors.forename: Megan C
authors.initials: MC
authors.lastname: Frost
authors.affiliation: Stem Cell and Tissue Engineering Lab, Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhao
mesh_terms: D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D003432:Cross-Linking Reagents / Q000737:chemistry; D055119:Elastic Modulus; D005780:Gelatin / Q000737:chemistry*; D006801:Humans; D020100:Hydrogels / Q000737:chemistry* / Q000494:pharmacology; D007477:Ions / Q000737:chemistry; D008670:Metals / Q000032:analysis / Q000737:chemistry* / Q000302:isolation & purification; D011137:Polystyrenes / Q000737:chemistry; D011145:Polyvinyls / Q000737:chemistry; D013053:Spectrophotometry; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D003432:Cross-Linking Reagents; D020100:Hydrogels; D007477:Ions; D008670:Metals; D011137:Polystyrenes; D011145:Polyvinyls; C006960:chelex; D005780:Gelatin
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