An eco-friendly colorimetric strategy based on gold nanoparticles modified with 3-pyridinylboronic acid for detecting copper ions

Abstract

Copper is an essential element in the human body. Excess accumulations of copper, however, would become a potential threat. Therefore, it is of great significance to detect copper ions. Owing to their controllable morphology, dispersal characteristics, high extinction coefficient, and easily functionalized surfaces, gold nanoparticles (AuNPs) have been highly employed as attractive sensing probes for environmental and biological analyses. We herein propose an eco-friendly colorimetric strategy based on AuNPs modified with 3-pyridinylboronic acid (PA) for sensitive and selective detection of copper ions (Cu2+) in water at trace level. The color changes of the system from wine-red to gray-blue with increasing amounts of copper ions is due to the binding of AuNPs modified with 3-pyridinylboronic acid to copper ions, which in turn leads to the aggregation of AuNPs with fine anti-interference. Strengths of the work: 1) rapid response time without complex pre-treatment; 2) high sensitivity with low limit of detection (LOD) and the good linear relationship (R2 = 0.98, LOD = 3.0 μM by the naked eye and 72 nM by ultraviolet-visible spectroscopy); 3) high selectivity under other interfering ions. In addition, the detection mechanism of this work has been successfully confirmed by density functional theory (DFT), transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), Zeta potential analysis and ultraviolet-visible spectroscopy (UV–vis).