Cancer is still one of the major reasons of illness and death throughout the world. Wide range of cancer types occur in many organs like breast, liver, lung, colon etc. The surface characteristics of these cells change, when normal cells transform into cancerous cells. Then, they display unique expression and/or over expression of certain receptors and antigens. Overexpression of these cells compare to normal cells makes them attractive for targeted therapy. Conjugation of monoclonal antibodies and/or small molecules like aptamers to the magnetic nanoparticles is a beneficial method for cancer diagnosis and treatment in terms of targeted therapy. Nanoparticles have a high surface area to volume ratio. Several types of nanoparticles including quantum dots, magnetic iron oxide, gold and polymer based nanoparticles have been developed for cancer applications in the last few years. In this study, developing of an early diagnosis nanoparticular system in order to detect and image human breast cancer cell line of MDA MB 231 was aimed. In this reason, it has been thought to target cell surface receptors of epidermal growth factor which expressed by breast tumor cells of MDA MB 231. To this end, gold coated magnetic nanoparticles were designed and characterized. Average size of synthesized SPIONs and gold-coated SPIONs which were determined by Transmission Electron Microscopy (TEM) were detected as 5.62 +/- 1.49 nm and 57.04 +/- 8.58 nm, respectively. Fluorescein isothiocyanate (FITC)-labelled aptamer and antibody molecules were immobilized onto gold-coated superparamagnetic iron oxide nanoparticles (SPIONs) and then developed carrier system was applied to MDA MB 231 breast cancer cells in the cell culture medium. The estrogen positive human fibroblast cells were chosen as control cells. Proliferation and differentiation of cells were investigated and cytotoxicity of nanoparticular carrier system was examined. The results indicated that various forms and concentrations of SPION were influenced the cytotoxicity results. Moreover, SPIONs were almost nontoxic to both cell lines without any modifications. Apoptosis and necrosis rates were quantified by double-staining of cells. The different forms of SPION formulations applied to MDA MB 231 breast cancer cells resulted in high incidence of apoptosis rather than necrosis. Additionally, the apoptotic and necrotic effects were found to be concentration dependent. Cancer cell selectivity and cell surface receptor based targeting was imaged by the Fluorescent Microscopy imaging technique and quantified by flow cytometry assay. Real time cell analyser (RTCA) was utilized to determine the dynamic cell proliferation on a periodic time intervals. In conclusion, cancer cell surface receptor based targeting by aptamer and monoclonal antibody conjugated SPIONs was successfully achieved.