A potential-gated molecularly imprinted smart electrode for nicotinamide analysis

Abstract

Triggered surface responsiveness paves the way for smart sensor technologies that not only have tunable retention, but also provide sensing through a ‘built-in’ programming of electrode material. In this study, we report a potential-gated electrochemical sensor for determination of nicotinamide (NAM) based on a molecularly imprinted overoxidised polypyrrole electrode. The sensitive layer was prepared by electropolymerisation of pyrrole on a glassy carbon electrode in the presence of NAM as a template molecule, followed by alkali extraction. Electrochemical methods were used to monitor the processes of electropolymerisation, template removal and binding in the presence of a [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻ redox couple as an electrochemical probe. Several factors affecting the performance of the MIP-modified electrode were investigated and optimized. The peak current of the ferro/ferricyanide couple decreased linearly with successive addition of NAM in the concentration range 0.9 × 10⁻⁶ to 9.9 × 10⁻³ M with a detection limit of 1.7 × 10⁻⁷ M (S/N = 3). The molecularly-imprinted polymer (MIP) electrode had excellent recognition capability for NAM compared to structurally related molecules. Moreover, the reproducibility and repeatability of the NAM-imprinted electrode were all found to be satisfactory. The results from sample analysis confirmed the applicability of the NAM-imprinted electrode to reusable quantitative analysis in commercial pharmaceutical samples.