In this study, a highly sensitive, fast, and selective enzyme-free electrochemical sensor based on the deposition of Ni cavities on conductive glass was proposed for insulin detection. Considering the growing prevalence of diabetes mellitus, an electrochemical sensor for the determination of insulin was proposed for the effective diagnosis of the disease. Colloidal lithography enabled deposition of nanostructured layer (substrate) with homogeneous distribution of Ni cavities on the electrode surface with a large active surface area. The morphology and structure of conductive indium tin oxide glass modified with Ni cavities (Ni-c-ITO) were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The diameter of the resulting cavities was approximately 500 nm, while their depth was calculated at 190 ± 4 nm and 188 ± 18 nm using AFM and SEM, respectively. The insulin assay performance was evaluated by cyclic voltammetry. Ni-c-ITO exhibited excellent analytical characteristics, including high sensitivity (1.032 μA μmol-1 dm3), a low detection limit (156 μmol dm-3), and a wide dynamic range (500 nmol dm-3 to 10 μmol dm-3). Finally, the determination of insulin in buffer with interferents and in real blood serum samples revealed high specificity and demonstrated the practical potential of the method.

Department of Biochemistry Faculty of Science Masaryk University Kamenice 5 625 00 Brno Czech Republic

Department of Physical Chemistry University of P J Šafárik in Košice Moyzesova 11 040 01 Košice Slovak Republic

Institute of Materials Research Slovak Academy of Sciences Watsonova 47 040 01 Košice Slovak Republic

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