Natural Silk Nanofibril-Directed Mineralization for Biomimetic Scaffolds.

Nature organizes the extracellular matrix into hierarchical structures, inspiring the design of biomimetic mineralization scaffolds. Silk fibroin, a noncollagenous structural protein, is a potential template for biomineralization. Here, we show the mineralization behavior of silk nanofibril (SNF) and demonstrate tunable biomineralization through the SNF assembly. We demonstrate the deposition of amorphous calcium phosphate and its transformation into flower-like hydroxyapatite crystals on the SNF interface by exploiting individual SNFs as a model. On two-dimensional (2D) films and three-dimensional (3D) scaffolds, SNF assembly influences the mineralization process. The dense nanofibrils in the SNF film and scaffold undergo mineralization through the anchoring and deposition of hydroxyapatite, whereas the modified 3D scaffolds with fluffy SNF are comparable to individual SNF. Consequently, silk nanotechnology makes use of a controllable assembly to build one-dimensional, 2D, and 3D nanostructures. These results offer new insights into the mineralization mechanisms of silk mesoscopic units and provide pathways for the synthesis of biomineralized scaffolds.