In another study, the functionalization of screen-printed carbon electrodes with Iridium oxide nanoparticles (IrO2 NPs) resulted in a sensing system that exhibited high performance for the detection of ApoE protein at LOD of 68 ng/mL [66], which is much lower than the ApoE level found in the CSF of AD model (9.09 μg/mL) [75]. This evidence concerns the gene APOE and Alzheimer disease.