Swelling and mechanical behaviors of chemically cross-linked hydrogels of elastin-like polypeptides.
Genetically engineered elastin-like polypeptides consisting of Val-Pro-Gly-X-Gly repeats, where X was chosen to be Lys every 7 or 17 pentapeptides (otherwise X was Val), were synthesized and expressed in E. coli, purified, and chemically cross-linked using tris-succinimidyl aminotriacetate to produce hydrogels. Swelling experiments indicate hydrogel mass decreases by 80-90% gradually over an approximate 50 degrees C temperature range. Gels ranged in stiffness from 0.24 to 3.7 kPa at 7 degrees C and from 1.6 to 15 kPa at 37 degrees C depending on protein concentration, lysine content, and molecular weight. Changes in gel stiffness and loss angle with cross-linking formulation suggest a low-temperature gel structure that is nearly completely elastic, where force is transmitted almost exclusively through fully extended polypeptide chains and chemical cross-links, and a high-temperature gel structure, where ELP chains are contracted and force is transmitted through chemical cross-links as well as frictional contact between polypeptide chains.
Trabbic-Carlson
Kimberly
K
Department of Biomedical Engineering, Box 90281, Duke University, Durham, North Carolina 27708-0281, USA.
Setton
Lori A
LA
Chilkoti
Ashutosh
A
D003432:Cross-Linking Reagents / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry*; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry*; D013314:Stress, Mechanical; D013696:Temperature; D013816:Thermodynamics
D003432:Cross-Linking Reagents; D020100:Hydrogels; D010455:Peptides; C033943:elastin polypentapeptide