A nanosol SERS/RRS aptamer assay of trace cobalt(ii) by covalent organic framework BtPD-loaded nanogold catalytic amplification

Abstract

The determination of heavy metal ions has always been a hot topic in the field of environmental analysis. In this study, a new covalent organic framework-loaded gold nanoparticle (AuCOF) nanocatalytic amplification signal strategy was developed to determine trace Co²⁺ in water. The COF of BtPD was synthesized from 1,3,5-benzene tricarboxaldehyde and p-phenylenediamine, and a new kind of AuBtPD nanosol was prepared by reduction of HAuCl₄ to AuNPs on the BtPD carrier. It has strong catalysis of the new indicator reaction of sodium formate reducing HAuCl₄ to AuNP sol with strong resonance Rayleigh scattering (RRS) at 370 nm and surface enhanced resonance Raman scattering (SERS) activity at 1614 cm⁻¹ in the presence of a Victoria blue 4R (VB4R) molecular probe. Combining the nanocatalytic reaction to amplify the dual-scattering signals and specific aptamer (Apt) of cobalt ions, a new, fast, stable, sensitive and specific dual mode method for detecting Co²⁺ was established; the RRS signal I_370nm and SERS signal I_1614cm⁻¹ show a linear relationship with the concentration of 0.033–1 nmol L⁻¹ Co²⁺ and with a limit of detection (LOD) of 0.02 nmol L⁻¹. The two methods have been applied to the determination of Co²⁺ in industrial wastewater, tap water and river water, and the results are satisfactory.