Label-free silver nanoparticles for visual colorimetric detection of etimicin

Abstract

A simple, rapid and ultrasensitive method for visual colorimetric detection of etimicin based on label-free silver nanoparticles (AgNPs) has been developed in this paper. Etimicin can induce the aggregation of AgNPs owing to the electrostatic attraction and hydrogen-bonding interaction, causing changes in absorption spectra and color of the AgNPs suspension. The concentration of etimicin can be determined by a UV-Vis spectrophotometer or even the naked eye. The effect of different factors such as pH, the concentration of AgNPs, reaction temperature and reaction time was investigated. Under the optimum conditions, this analytical method showed an ultralow detection limit of 3.59 × 10⁻⁷ mol L⁻¹ for etimicin. Furthermore, as low as 4 × 10⁻⁷ mol L⁻¹ etimicin can be visualized by the naked eye without the requirement of any complicated or expensive instruments. The AgNPs sensor also showed good selectivity in the presence of potential interfering substances. The proposed method has been successfully applied to determine the concentration of etimicin in human urine, and may provide new opportunities in the development of sensors for clinical monitoring of etimicin in the future.