A nanostructured label-free platform based on an ultrathin film for ultrasensitive detection of a secosteroid hormone

Abstract

We report the electrocatalytic activity of perovskite-type LaNiO₃-nanoxide (LN-NO) on secosteroid hormone oxidation in alkaline solution. LN-NO was synthesized by the Pechini method and calcined at 973 K for 2 h under air atmosphere. Subsequently, the LN-NO material was studied by high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffractometer (XRD) and electrochemical techniques such as cyclic voltammetry (CV), square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS). The Rietveld refinement by the XRD pattern indicated the presence only the LN-NO. Optimized electrocatalytic activity was achieved using the LN-NO architecture, on a label-free platform, and nanostructures with sizes ranging between 50 and 100 nm were well distributed throughout the nanoxide. The detection of the secosteroid was performed at a low potential (0.46 V vs. Ag/AgCl) in a range between 0 and 2.6 × 10⁻⁵ mol L⁻¹, with a detection limit of 8.3 × 10⁻⁷ mol L⁻¹, which is considerably competitive with similar devices. The application of the LN-NO nanostructured label-free platform as a voltammetric sensor showed a good sensitivity of 17.75 A M⁻¹. Finally, the use of LN-NO as a low-cost alternative to carbon nanomaterials (nanotubes and graphene) has the potential to be an excellent approach to sensor development.