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Fabrication of nonenzymatic biosensors based on the nanomaterials for highly sensitive and selective detection of single or multiple molecules coexisting in one biological sample is extremely challenging. Design of the hierarchical nanohexagonal Fe2O3 platelets (HFP) via one-pot hydrothermal treatment was employed for selective signaling of dopamine (DA) and uric acid (UA) in the presence of ascorbic acid (AA) with high sensitivity. Electrode design with the nanosized structure of parallel hexagonal platelets (20-40 nm), high surface area, multiactive site, smooth surface, and pore distribution inside/outside the surfaces renders excellent sensitivity and selectivity of DA and UA during the catalytic oxidation process. Simultaneous monitoring and selective signaling of DA and UA were successfully achieved by HFP with detection limits as low as 16 nM and 0.218 μM with a wide linear range from 1 to 200 μM and from 20 to 400 μM for DA and UA, respectively. HFP provides high stability and reproducibility with relative standard deviations in the range of 2.5-5.29% to monitor DA and UA. Furthermore, continuous monitoring of DA and UA in real human saliva/serum samples was realized with high sensitivity and selectivity. The designed HFP can be employed as a nonenzymatic biosensor for simultaneous detection of mono-bioactive molecules in the biological samples.The electrooxidation of DA and UA at the surfaces of Fe2O3.The electrocatalytic active sites bind with the DA and UA through hydrogen bonds at the surface of Fe2O3. Through the DPV or CV scanning, the electrooxidation of DA and UA proceeded and the oxidized form quinolone-DA and keto-UA were obtained with losing of 2e−/2H+. [ABSTRACT FROM AUTHOR]