Naked Eye Detection of Cr³⁺ and Ni²⁺ Ions by Gold Nanoparticles Modified with Ribavirin

Abstract

This paper reports the synthesis of ribavirin-modified gold nanoparticles (ribavirin-AuNPs) in aqueous media, characterized by FTIR spectroscopy, ultraviolet–visible spectroscopy (UV–vis), and transmission electron microscopy (TEM). Ribavirin-AuNPs were employed as colorimetric probes to detect Cr³⁺ and Ni²⁺ in the pH range of 3–8 and 25 ^∘C in aqueous solutions by the color change of the system. In the solution, ribavirin-AuNPs were red in color and the surface plasmon absorption band was centered at 530 nm. In the presence of Cr³⁺ and Ni²⁺, ribavirin-AuNPs induced the aggregation of nanoparticles, and the surface plasmon absorption changed to 540 nm. Upon aggregation, the surface plasmon absorption band red-shifted and, thus, the nanoparticle solution appeared blue. The sensitivity of ribavirin-AuNPs toward other metal ions, i.e. Mg²⁺, Mn²⁺, Cr⁶⁺, Na⁺, Ni²⁺, Ag⁺, Al³⁺, Ca²⁺, Cd²⁺, K⁺, Cd²⁺, Cu²⁺, Fe²⁺, Fe³⁺, Hg²⁺, Co³⁺, Ni²⁺, Pb²⁺, and Zn²⁺, was negligible. This highly selective sensor allowed for the direct quantitative assay of Ni²⁺ and Cr³⁺. The limits of detections were found to be 25.2 and 30.5 nM for Ni²⁺ and Cr³⁺ on the basis of the signal-to-noise ratio of 3:1 and correlation coefficients (R²) of 0.9813 and 0.99489 for Ni²⁺ and Cr³⁺, respectively.