A bone mimic based on the self-assembly of hydroxyapatite on chemically functionalized single-walled carbon nanotubes

We report the use of chemically functionalized single-walled carbon nanotubes (SWNTs) as a scaffold for the growth of artificial bone material. The mineralization of SWNTs functionalized with phosphonates and poly(aminobenzene sulfonic acid) (PABS) was investigated in the solution phase and as films on substrates. Microscopy studies showed that hydroxyapatite (HA) nucleated and crystallized on the surface of the functionalized SWNTs. The negatively charged functional groups on SWNTs attract the calcium cations and lead to self-assembly of HA. The thickness of the HA layers was found to be a function of the mineralization time. Mineralization of SWNT-PABS films led to well-aligned plate-shaped HA crystals and the thickness of the crystals reached 3 mu m after 14 days of mineralization. The PABS- and phosphonates-functionalized SWNTs can be applied as supporting scaffold for bone therapy.