Effects of poloxamer on the gelation of silk sericin

Abstract

Effects of the concentration of poloxamer 407, temperature, and the concentration of sericin on the gelation of silk sericin (SS) were studied. Gelation of SS was accelerated with an increase in poloxamer concentration and temperature. The sol-gel transition of SS became irreversible with respect to the temperature in the presence of poloxamer, whereas the sol-gel transition of SS itself was reversible. Infrared (IR) and circular dichroism (CD) spectra show that the conformational change of SS in the presence of poloxamer was accelerated from random coil to β-structure. X-ray diffraction and differential scanning calorimetry (DSC) show that the crystalline structure of poloxamer in the mixture was affected by the presence of SS and that its melting temperature was shifted to lower temperature with increasing SS content, indicating an interaction between poloxamer and SS through hydrogen and hydrophobic bondings.