Magnetic nanoparticulate systems based on polymeric materials such as poly (lactic-co-glycolic acid) (PLGA) are being studied for their potential applications in targeted therapy and imaging of malignant tumors. In the current study, superparamagnetic iron oxide nanocrystals (SPIONs) and doxorubicin (Dox) were entrapped in the PLGA-based nanoparticles via a modified multiple emulsion solvent evaporation method. Furthermore, SPIO/Dox-NPs were conjugated to anti-nucleolin AS1411 aptamer (Apt) and their targeting ability was investigated in high nucleolin-expressing C6 glioma cells compared to low nucleolin-expressing L929 cells. The NPs exhibited a narrow size distribution with mean diameter of 170nm and an appropriate SPION content (18% of total polymer weight) with a sufficient saturation magnetization value of 5.9emu/g which is suitable for imaging objectives. They manifested an increased Dox release at pH5.5 compared to pH7.4, with initial burst release (within 24h) followed by sustained release of Dox for 36days. The Apt conjugation to NPs enhanced cellular uptake of Dox in C6 glioma cells compared to L929 cells. Similarly, the Apt-NPs increased the cytotoxicity effect of Dox compared with NPs and Dox solution (f-Dox) alone. In conclusion, the Apt-NPs were found to be a promising delivery system for therapeutic and diagnostic purposes.