Synergistic effect of bimetallic Ag@Cu nanorods modified electrode for enhanced electrochemical sensing of thiocyanate ions

摘要

The thiocyanate (SCN-) level in human saliva, serum, and blood has been considered as a biomarker for analyzing the practice of cigarette smokers. Here, we have developed a highly sensitive and selective electrochemical sensor for SCN- in phosphate buffer using an Ag@Cu bimetallic nanorods (NRDs) modified glassy carbon electrode (GCE). The bimetallic Ag@Cu NRDs were grown on the GCE surface by a simple seed-mediated growth method. Initially, Ag seeds were deposited on the Nafion coated GCE. The deposited Ag-seeds in turn accelerate the growth of bimetallic Ag@Cu NRDs in the presence of cetyltrimethyl ammonium bromide, which acts as a soft template for the one-dimensional growth of NRDs. The synthesised NRDs were characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy measurements. The Ag@Cu NRDs modified electrode shows an excellent response towards the electrochemical oxidation of SCN-. Cyclic voltammetry was used to study the linear correlation of SCN- oxidation between 1 and 10 mM, and, subsequently, 10 nM was achieved as the detection limit with a signal to noise ratio (S/N = 3) for Ag@Cu bimetallic NRDs modified GCE. This unique sensor shows a high selectivity towards trace amounts of SCN- in the presence of various interfering cations and anions. It satisfactorily recognized the generated SCN- in a real-time application such as in human saliva. Finally, the fingerprint of SCN- existence in the saliva samples of cigarette smokers and non-smokers were differentiated in a short span of time with ease.