Fabrication of an alternative regenerated silk fibroin nanofiber and carbonated hydroxyapatite multilayered composite via layer-by-layer

A novel multilayered composite consisting of regenerated silk fibroin (RSF) nanofiber and carbonated hydroxyapatite (CHA) was fabricated with the combination of electrospinning of RSF aqueous solution and soaking in CaCl₂ and Na₂HPO₄ solutions alternately. The chemical composition and morphologies of RSF/CHA composite were characterized by FT-IR, XRD, TGA, EDX, and SEM. The results showed that such an organic/inorganic composite had an alternate layered structure, while the CHA mineral partly penetrated into the porous RSF mats, which was similar to the structure of natural nacre. By tuning the CHA deposition procedure and RSF electrospinning condition independently, the thickness of each layer of CHA and RSF, as well as the layer numbers of composite, could be easily regulated. For example, the average thickness of CHA layers with 5 and 10 mineralization cycles were 1.63 and 3.19 μm, while 9.03 and 30.12 μm of porous RSF nanofiber layers could be formed with 7 and 24 h electrospinning process, respectively. Thus, it may provide an efficient and general approach to produce a series of inorganic/organic multilayered biomaterials for biomedical engineering.