Synthesis and characterization of porous β-cyclodextrin/manganese ferrite nanoparticles and their application as an electrochemical sensor of dopamine

Superparamagnetic manganese ferrite nanoparticles stabilized with β-cyclodextrin (βCD-MFO) were prepared by co-precipitation at room temperature and hydrothermal methods using temperatures of 120 and 140 °C. Similar samples, without βCD, were prepared for comparison (MFO). Samples called βCD-MFO140 and MFO140, heated at 140 °C during the synthesis, showed the best characteristics. The βCD-MFO140 is formed by nanoparticles of 5 nm and it presents the highest surface area, the highest porosity, and a hydrophilic surface. Alternatively, the MFO140 presented a crystallite size near 25 nm and a hydrophobic surface. Both nanocomposites were applied to modify carbon paste electrodes and evaluated using differential pulse voltammetry for the determination of dopamine. They showed promising responses such as sensitivities of 0.09 and 0.23 µA µmol⁻¹ L and low detection limit of 2.28 and 0.39 µmol L⁻¹ for MFO140 and βCD-MFO140, respectively, in a linear range between 11.97 and 39.68 µmol L⁻¹ for MFO140 and between 3.99 and 15.95 µmol L⁻¹ for βCD-MFO140. Both sensors demonstrated good reproducibility with a relative standard deviation of 12.7%. The CPE βCD-MFO140 exhibits better selectivity for dopamine. According to these results, the βCD-MFO140 electrode demonstrated better electrochemical performance with potential for application in real samples, which can be ascribed to its higher surface area and porosity, as well as its hydroxylated surface that makes this electrode more hydrophilic.