The practicability of application of single wall carbon nanotubes doped with iron oxide nanoparticles (Fe3O4-iSWNTs) and coated with Poly (lactic acid)-co-methoxy polyethylene glycol copolymeric (PLA-comPEG) micelles as a smart drug delivery systems based on hybrid nanomaterials (HNDDSs) for the puissant chemotherapy agent Docetaxel (DTX) were studied. The SWNTs treatment in the acidic medium leads to formation of carboxylate groups on the surface of SWNTs and functionalization by iron oxide nanoparticles, Then PLA-co-mPEG was synthesized by ring-opening polymerization and prepared in the form of micelles and coated the Fe3O4-iSWNTs.The surface functionalization of nanomaterials and the type of surface-interaction were characterized by Fourier transform spectroscopy (FT-IR), proton nuclear magnetic resonance (H-NMR), X-ray powder diffraction (XRD), vibrating sample magnetometers (VSM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), field-emission gun scanning electron microscope and energy dispersive X-ray (FE-SEM-EDX). The particle size of nanocomposites examined by FE-SEM was in the range of 15-50 nm. The in-vitro drug release and cytotoxicity investigations of DTX loaded on Fe3O4-iSWNTs/PLA-co-mPEG nanocomposites were also studied. Docetaxel release in tumor environment simulated conditions showed sustained release manner (43.7% was released during 348.5 h) And kinetic mechanism of release according to log-probability equation. The designed nanocomposite showed no apparent evidence of toxicity to MCF7 cancer cells while DTXloaded nanocomposites indicated enhanced antitumor activity in comparison to free DTX, 59% and 36% of the cells were viable after incubation, respectively. It was concluded that these findings may open the possibilities for targeted and sustained delivery of DTX to the cancerous tissues under external magnetic fields. (C) 2017 Elsevier Ltd. All rights reserved.