Carbon nanotube-reinforced chitosan (CNT-CS) biomaterials with in vivo and in vitro bioactivity and mechanical strength. (A) MTT assay of the viability of an MG-63 osteoblast-like cell; (b) protein estimation; and (c) Alkaline phosphatase (ALP) activity of an osteoblast-like MG-63 cell on different CS–MWCNT composite scaffolds as a function of time. (B) The surgical implantation of (a) rhBMP-2 adsorbed MWCNT–CS scaffolds into the subcutaneous muscular pocket of a mouse; (b) optical microscope micrograph of regenerated bone tissue; (c,d) optical micrograph in detail of regenerated bone tissue (blue–green), the remaining scaffold (black), and plenty of fibroblasts (purple colored) after major disassembly of the MWCNT/CS scaffold, surrounded by muscle tissue (pink). (C) MC3T3-E1 cells spreading on interconnected porous HA ceramic (a,c) and 3D-porous CNT (b,d) scaffolds (actin filaments: red; nucleus: blue). Reproduced with permission from [159,163,164]. Elsevier, 2012, 2008; MDPI: Open Access, 2017.