Nucleation and Assembly of Silica into Protein-Based Nanocomposites as Effective Anticancer Drug Carriers Using Self-Assembled Silk Protein Nanostructures as Biotemplates

Bombyx mori (B. mori) silk fibroin and sericin can act as a great candidate in delivering drugs or other bioactive substances. Silica also has a great application in the field of drug delivery. To the best of our knowledge, there has been no report on the design of a nanocomposite made of silk protein and silica for drug delivery. Here, for the first time, we used B. mori silk fibroin (SF) and sericin (SS), self-assembled into nanospheres and nanofibers in situ in the aqueous solution, respectively, as a biotemplate to regulate the nucleation and self-assembly of silica for designing anticancer drug delivery. SF and SS mediated the nucleation and assembly of silica into monodispersed nanospheres (termed Si/SF) and nanofibers (termed Si/SS), respectively. The size and topography of the silica assemblies were dependent on the concentration of SF or SS as well as reaction conditions. Both Si/SF nanospheres and Si/SS nanofibers showed a high loading capability and sustained release profile of an anticancer drug, doxorubicin (DOX), in vitro. Si/SF nanospheres were found to be efficiently internalized in human cervical carcinoma (HeLa) cells and accumulate around the cell nuclei. Si/SS nanofibers could only adhere to the surface of the cancer cells. This indicates that DOX-loaded Si/SF nanospheres and Si/SS nanofibers are more effective in cancer therapy than free DOX. Our results suggest that the self-assembled Si/SF spheres and Si/SS nanofibers are potential effective anticancer drug carriers.