Fe3O4 magnetic nanoparticles (MNPs) were synthesized and silanized to form a core-shell (Fe3O4-SiO2) structure. Afterwards, surface modification with amino silane was carried out to produce amino groups on the MNPs for the biomolecule immobilization. In order to test the performance of amino functional MNPs as immobilization platform in biosensing applications, glucose oxidase was immobilized on the surface via glutaraldehyde. Obtained Bio-MNPs were then fixed onto the carbon paste electrode by the aid of magnetic force and used as the working electrode during the amperometric measurements at -0.7 V versus Ag/AgCl. After optimization of some parameters affecting the biosensor performance, analytical characterization was carried out. Linearity was found in the range of 0.25-2.0 mM glucose and defined by the equation of y = 8.366x + 1.819, (R (2) = 0.996). Proposed biosensor was then applied for the glucose analysis in various beverages. Finally, data were compared with a commercial enzyme assay kit based on spectrophotometric Trinder reaction as a reference method.