A high-sensitivity amperometric glucose biosensor was developed using iron oxide nanoparticles (IONPs), glucose oxidase (GOx) enzyme, and Nafion layer immobilized on screen-printed carbon electrode (SPCE) (Nafion/GOx/IONPs/SPCE). IONPs were synthesized through precipitation and functionalized with citric acid (CA) to provide a hydrophilic surface and functional groups for immobilization of the GOx enzyme. The transmission electron microscopy image showed that size of the obtained IONPs is similar to 20 nm. The X-ray diffraction pattern showed the presence of spinel cubic lattice of maghemite (gamma-Fe2O3). Under the optimal condition, the amperometric responses of the resulting bioelectrode Nafion/GOx/CA-IONPs/SPCE presented high sensitivities of 175 and 5.31 mu AmM (1)cm (2) for the detection of 0.02-0.25 and 0.25-8.00 mM glucose, respectively. The biosensor exhibited low limit of detection of 7 mu M, good repeatability by maintaining 93% of the initial peak current after 10 cycles of cyclic voltammetry measurement, and sufficient reproducibility of 4.2% (number of sensors n = 7). The fabricated amperometric biosensor features high sensitivity, disposability, low cost, and simple procedure for glucose detection. (C) 2017 Elsevier Ltd. All rights reserved.