Screen-Printed\nNanohybrid Palladium-Based Electrodes\nfor Fast and Simple Determination of Estradiol in Livestock

One of the main challenges in animal breeding systems\nis determining\nestradiol (E2) in livestock samples as simple and minimally invasive\nas possible, Thus, a nonenzymatic biosensor screen-printed electrode\n(SPE) was developed by modifying nanohybrid palladium nanoparticles\n(PdNPs), and carbon dots anchored on a nanosilica particle (PdNPs/C.dots/SiO<sub>2</sub>), denominated SPE/PdNPs/C.dots/SiO<sub>2</sub>, and successfully\ntested for the direct detection of estradiol in livestock samples.\nPdNPs were directly obtained by a one-step synthesis through carbon\ndot reduction. Hybrid nanomaterials were characterized by atomic force\nmicroscopy, high-resolution transmission electron microscopy, and\nelectrochemical impedance. The combination of PdNPs with C.dots resulted\nin a nonenzymatic biosensor supported on a screen-printed platform\nwith superior electrocatalytic properties regarding the oxidation\nof E2 when compared to unmodified sensors. Modifications in the working\nelectrode resulted in high sensitivity toward E2 determination within\na linear range from 0.005 to 14.0 μmol L<sup>–1</sup> with a limit of detection of 1.0 nmol L<sup>–1</sup>. The\nrecovery rate of E2 in bovine serum samples and urine samples ranged\nfrom 92 to 106%. Interference studies showed that peak current variation\n(Δ<i>i</i><sub>p</sub>) among all interferents evaluated\nand E2 did not exceed ±2%. The newly developed sensor stands\nout not only for its high sensitivity but also for its quick and simple\nway of production while also being disposable after analysis, providing\na simple, sensitive, and practical approach for the determination\nof reproductive hormones in livestock.