ELECTROSTATIC IMMOBILIZATION OF ssDNA ON NANOSTRUCTURED NIOBIUM OXIDE FOR ELECTROCHEMICAL GENOSENSOR APPLICATION

Niobium-based oxides have been suggested for several applications, including biosensors [1]. Genosensors are a class of biosensors that has attracted interest in the sensing field because they are considered low-cost, highly specific, and have rapid target recognition. Furthermore, nanostructured materials can enhance these attributes. Usually, in a genosensor, the bioreceptor is a single nucleic acid strand, which will hybridize with the target nucleic acid. Therefore, the main goal of this work was to evaluate the electrostatic immobilization procedure of a bioreceptor (single strands of DNA (ssDNA)) on a nanostructured niobium oxide surface. For this purpose, 20 µL of 100 µM of ssDNA was immobilized on a nanostructured niobium oxide electrode [2] with the support of tris-EDTA buffer (TE; pH 8.0). The electrochemical response of the electrode was conducted by cyclic voltammetry tests performed using 1 M Na₂SO₄ as electrolyte, Ag/AgCl (3.5 M KCl) reference electrode, platinum counter electrode, scan rate of 50 mV.s^-1 in the potential window from -0.2 V to -1 V. It was possible to detect different peak current results at -1 V between the non-immobilized electrode (-30 µA.cm^-2) and the immobilized electrode (-79.5 µA.cm^-2). Therefore, these results demonstrated the effectiveness of the proposed electrostatic immobilization of ssDNA on the surface of the electrode made of nanostructured niobium oxide.