In this research, oligoamino-ester grafted magnetite nanoparticles (AEMNPs) with dendritic and linear architecture were synthesized and the effect of morphology and chemical structures of these modified MNPs on the secondary structure of adsorbed protein have been investigated. In the first step, the synthesized magnetic nanoparticles were modified with 3-(triethoxysily1) propylamine (APTES). The sequential reaction of these silica coated nanoparticles with acryloyl chloride and diethanolamine will produce the first (G1), second (G2) and third (G3) generations of fluffy shaped nanoparticles. Three generations of these nanoparticles with linear structure were obtained in the presence of 2-(diethylamino) ethanol instead of diethanolamine. FT-IR, thermal gravimetric analysis (TGA), dynamic light scattering (DLS) and zeta potential techniques were used to identify the final structure of all dendrimers. Antibiofouling properties of AEMNPs were analyzed in two different concentrations of fetal bovine serum and the effect of various factors such as zeta potential, density and the surface hydroxyl groups were evaluated by DLS, UV-vis and fluorometric methods. Circular dichroism spectra of FBS in the presence of various amounts of nanoparticles provided information about protein secondary structures. (C) 2014 Elsevier Ltd. All rights reserved.