Carbon nanotube-gelatin-hydroxyapatite nanohybrids with multilayer core–shell structure for mimicking natural bone

Abstract

We attempted to mimic collagen fibrils bearing apatite crystals in natural bone, using gelatin, carboxylic acid functionalized carbon nanotubes (f-CNTs), and hydroxyapatite (HA). Gelatin molecules were covalently grafted on the surface of f-CNTs by the formation of amide linkages. HA crystals were then assembled onto the gelatin-grafted f-CNTs in a highly concentrated CaP solution, resulting a multilayered core–shell structure, consisting of a f-CNT core and gelatin-HA shells (as a fibrous multilayered f-CNT/Gel/HA nanohybrid), and in a similar formation to the collagen fibers of natural bone. The tensile strength, elastic modulus, and elongation rate of the new hybrid material were significantly improved compared to both pure (f-CNT free) gelatin and a mixture of f-CNT and gelatin, by 4.6–8.8, 9–10, and 28–42 times, respectively. Cell viability studies of the f-CNT/Gel/HA nanohybrid also suggest a higher degree of biocompatibility compared to pure gelatin.