Synthesis, characterization and in vitro evaluation of dendrimer-MWCNT reinforced SrHAP composite for bone tissue engineering

This study aimed to improve the mechanical, drug loading/release and bioactive characteristics of hydroxyapatite (HAP). The covalent functionalization of PAMAM dendrimer with MWCNT (d-MWCNT), and in situ synthesis of strontium substituted HAP (SrHAP) on d-MWCNT yielded a composite, d-MWCNT-SrHAP. The composite was characterized by FT-IR, XRD, HR-SEM, AFM, EDS, TGA and zeta potential. It was hydrophilic (water contact angle 25.25 +/- 4.21), porous (89.63 +/- 2.4%), bioresorbable, mechanically strong (0.415 +/- 0.04 GPa) and protein adsorbing. The d-MWCNT-SrHAP exhibited a 30-fold increase in curcumin loading and a 1.7 fold delay in burst release compared to SrHAP. Further, in vitro studies using human osteoblast-like MG-63 cells demonstrated that the curcumin-loaded composite, d-MWCNT-SrHAP-C, encouraged osteoblast survival, proliferation, differentiation and matrix mineralization. The desirable physico-chemical properties and in vitro bioactivity of the d-MWCNT-SrHAP-C composite strongly suggest its potential application as a drug delivery system in hard tissue engineering.