Abstract
This paper describes the development of a sensor for the determination of metronidazole using a simple method involving the creation of nanoporous structures on gold electrodes followed by modification with self-assembled monolayers (SAMs) of thiols. The initial formation of oxidized gold species at pH 7.0 was followed by potentiodynamic reduction in order to obtain a nanostructured surface that was then modified with a SAM of cysteine. The sensor was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and electrochemical techniques. Quantification of metronidazole was performed using optimized square wave voltammetry. Under the best analytical conditions, the sensor operated at -0.36 V showed a linear range of 50-300 µmol L-1 and a limit of detection (LOD) of 2.6 µmol L-1. Evaluation of selectivity demonstrated that the electrode provided higher sensitivity towards nitroimidazoles. The sensor responses showed that it could be used for detection of metronidazole in different types of matrix.
Highlights
It is well known that gold reacts with sulfur to form thermodynamically and kinetically stable self-assembled monolayers (SAM) that are widely used in the manufacture of sensors and biosensors, where they act as molecular electronic biointerfaces.[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16] Thiols[17,18] are used to improve the stability of these devices and to transfer analyte redox information to the metal surface
The present work describes a new and simple procedure for producing a nanostructured gold electrode modified with a cysteine self-assembled monolayers (SAMs) for the determination of metronidazole in pharmaceutical formulations and biological samples
When the gold electrode was treated by chronoamperometry (2.0 V for 180 s) in an alkaline medium (0.5 mol L−1 KOH), there was the formation of Au(OH)3/AuO2 species in equilibrium on its surface, as indicated in the Pourbaix diagram (Figure 1).[39]
Summary
It is well known that gold reacts with sulfur to form thermodynamically and kinetically stable self-assembled monolayers (SAM) that are widely used in the manufacture of sensors and biosensors, where they act as molecular electronic biointerfaces.[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16] Thiols[17,18] are used to improve the stability of these devices and to transfer analyte redox information to the metal surface. The present work describes a new and simple procedure for producing a nanostructured gold electrode modified with a cysteine SAM for the determination of metronidazole in pharmaceutical formulations and biological samples.
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