Gold–deferrioxamine nanometric interface for selective recognition of Fe(III) using square wave voltammetry and electrochemical impedance spectroscopy methods

Deferrioxamine, a bacterial hydroxamic siderophore having high binding affinity for Fe(III), is used in its immobilized form, as self-assembled monolayer on Au, for accumulation and recognition of Fe(III) from the solution phase. The accumulated Fe(III) is detected via both active mode based on faradaic reduction current of Fe(III), and inactive mode based on impedimetric effect of accumulated Fe(III) against redox reaction of a suitable probe. Appropriate electrochemical techniques, square wave voltammetry and electrochemical impedance spectroscopy, are used for the transduction of analytical signals obtained by this sensor. Then, the parameters influencing the sensor response are optimized. In the best conditions, a linear response, from 1.0×10−10 to 1.0×10−7 M Fe(III) in logarithmic scale with a detection limit of 2.0×10−11 M, and mean relative standard deviation of 1.7% for n=4 is observed. The results show that the sensor can be used for determination of Fe(III) in the presence of various inorganic ions and biological species. Validity of the method and applicability of the sensor are successfully tested by determination of Fe(III) in various real samples including plant tissue (corn leaves), industrial alloy (Ferrotitanium), and pharmaceutical samples (Venofer® ampoule, Ironorm® capsule, and V.M. Protein® powder).

► A new biosensor using Deferrioxamine, a bacterial siderophore, fixed on Au is explained for Fe(III). ► The sensor is characterized by voltammetry and electrochemical impedance spectroscopy. ► Merits of the method include easy fabrication, wide response range, high selectivity and stability. ► The sensor is successfully tested for Fe(III) in pharmaceutical, industrial, and plant samples.