Here, we report the fabrication of a
curcumin-releasing porous
silk fibroin scaffold by simple mixing of
fibroin solution (aqueous) with
curcumin solution (organic) followed by freeze-thaw of the mixture. The scaffold has a uniform pore distribution with an average pore size of ~115 μm and a degree of swelling of 2.42% and water uptake capacity of 70.81%.
Fibroin showed thermal stability up to ~280°C, whereas encapsulated
curcumin disintegrated at ~180°C. Fourier transform infrared,
powder X-ray diffraction, and nuclear magnetic resonance studies together with UV-visible and fluorescence spectroscopy investigations revealed the
solvent (which was used to dissolve
curcumin) induced conformational transition of
fibroin from
silk-I to
silk-II that led to the formation of water-stable structure. Fluorescence spectroscopy data also suggested the presence of hydrophobic domains in
fibroin and encapsulation of
curcumin in such domains through hydrophobic interactions. Release kinetics and mathematical modeling studies indicated a slow and sustained release profile with diffusion as the predominant mode of release. Further, in vitro anticancer,
antioxidant, and antimicrobial assays suggested that the
biological activity of encapsulated
curcumin remains unaltered. The fabrication process is simple, reproducible, and does not require any sophisticated instruments or toxic crosslinking agents. It is anticipated that the
curcumin-loaded
fibroin scaffold could be used in soft tissue replacements including localized postsurgical
chemotherapy against
tumors, dressing material for quick healing of
wounds and
burns, and other related applications.