Voltammetric behavior of selenocystine at modified gold substrates

•The reduction of selenocystine at selenium-modified gold electrodes is reported.•Diffusionally controlled voltammetry is observed following surface modification.•The proposed gold–selenium film is readily achieved via electrochemical cycling under mild conditions.

The voltammetric response of seleno-l-cystine has been studied at gold substrates under physiological conditions. The reactivity of diselenides is utilized to generate a modified electrode surface, which in turn allows for electroanalysis of solution-based selenium species. Stable and reproducible voltammetry is observed for selenocystine reduction at pH 7 on selenium-modified gold substrates (Emid = − 486 mV vs. Ag/AgCl) and is consistent with a diffusionally controlled process. Modification of the gold surface is readily achieved via electrochemical cycling in the presence of a diselenide source at conventional scan rates. These studies afford voltammetric characterization of the selenocystine/selenocysteine redox couple under physiologically relevant conditions and highlight the potential utility of selenium-modified substrates for electroanalysis of chalcogen-containing species.