Abstract
Summary: Novel protein‐based hydrogels have been prepared by blending gelatin (G) with amorphous Bombyx mori silk fibroin (SF) and subsequently promoting the formation of β‐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 °C in blends prior to the formation of β‐sheet crystals. Introducing the β‐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.
Thermally reversible helix‐coil conformational transition of gelatin in mixed gelatin/silk fibroin hydrogels.
magnified imageThermally reversible helix‐coil conformational transition of gelatin in mixed gelatin/silk fibroin hydrogels.