Magnetic nanoparticles (MNPs), in comparison with traditional drug solutions or suspensions, represent a promising vehicle to achieve the controlled drug delivery to targeted cell/tissue regions in cancer treatment. In this study, the biodegradable chitosan-modified magnetite (Fe3O4) NPs (CS-MNPs) are firstly synthesized using as nanocarriers, and then encapsulated with anti-tumor drug doxorubicin (DOX) to construct DOX-loaded CS-MNPs (DOX-CS-MNPs), which are further applied to assay apoptosis of glioblastoma multiforme U251 cells. The properties of the DOX-CS-MNPs including particle size, shape and magnetization, are characterized. The stability, drug release, magnetic response and redispersion of the DOX-CS-MNPs within an external magnetic field are evaluated. Furthermore, the biological effects of the DOX-CS-MNPs on U251 glioblastoma cells, particularly cytotoxicity, cell viability, actin cytoskeleton and apoptosis rate, are subsequently investigated. The data show that the prepared DOX-CS-MNPs are spherical in shape with average diameter of 60 nm approximately. The fabricated DOX-CS-MNPs also exhibit specific properties including low aggregation, high saturation magnetization, satisfactory magnetic-responsive aggregation, and redispersion in water, etc. The biological assays show that the DOX-CS-MNPs can efficiently enter the cells, reduce cell viability, and inhibit cell proliferation in a dose-dependent manner, and a high rate of cell apoptosis is induced in U251 glioblastoma cells after DOX-CS-MNPs treatment. Therefore, the present results indicate that the constructed DOX-CS-MNPs may be a promising vehicle for efficiently inhibiting proliferation of human U251 glioblastoma cells. (C) 2014 Elsevier Inc. All rights reserved.