Effect of beta-sheet crystals on the thermal and rheological behavior of protein-based hydrogels derived from gelatin and silk fibroin.
Novel protein-based hydrogels have been prepared by blending gelatin (G) with amorphous Bombyx mori silk fibroin (SF) and subsequently promoting the formation of beta-sheet crystals in SF upon exposure to methanol or methanol/water solutions. Differential scanning calorimetry of the resultant hydrogels confirms the presence and thermoreversibility of the G helix-coil transition between ambient and body temperature at high G concentrations. At low G concentrations, this transition is shifted to higher temperatures and becomes progressively less pronounced. Complementary dynamic rheological measurements reveal solid-liquid cross-over at the G helix-coil transition temperature typically between 30 and 36 degrees C in blends prior to the formation of beta-sheet crystals. Introducing the beta-sheet conformation in SF stabilizes the hydrogel network and extends the solid-like behavior of the hydrogels to elevated temperatures beyond body temperature with as little as 10 wt.-% SF. The temperature-dependent elastic modulus across the G helix-coil transition is reversible, indicating that the conformational change in G can be used in stabilized G/SF hydrogels to induce thermally triggered encapsulant release.
Gil
Eun S
ES
Fiber and Polymer Science Program, North Carolina State University, Raleigh, NC 27695, USA.
Spontak
Richard J
RJ
Hudson
Samuel M
SM
D000818:Animals; D012831:Bombyx / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D005349:Fibroins / Q000737:chemistry*; D005780:Gelatin / Q000737:chemistry*; D006358:Hot Temperature; D020100:Hydrogels / Q000737:chemistry*; D019476:Insect Proteins / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013552:Swine
D020100:Hydrogels; D019476:Insect Proteins; D005780:Gelatin; D005349:Fibroins