Upconversion nanoparticles/carbon dots (UCNPs@CDs) composite for simultaneous detection and speciation of divalent and trivalent iron ions

Abstract

In this study, the application of carbon dots (CDs) modified NaYF₄:Yb, Er nanoparticles (UCNPs@CDs) as the fluorescent nanoprobe for simultaneous detection of Fe²⁺ and Fe³⁺ was investigated. Fe³⁺ quantification (5-80 μmol L^-1) was achieved, as a result of Fe³⁺ induced fluorescence quenching of UCNPs@CDs at 434 nm (under the 336 nm excitation). The chelate (Fe²⁺-phen) formed by Fe²⁺ and 1,10-phenanthroline had a broad absorption centered at 510 nm, due to inner filter effect (IFE), Fe²⁺ quantification (4-120 μmol L^-1) was achieved as a result of (Fe²⁺-phen) induced fluorescence quenching of UCNPs@CDs at 545 nm (under the 980 nm excitation). The resultant UCNPs@CDs probe, with excellent anti-interference capability, favorable fluorescence stability, and convincing performance in real sample analysis, showed promising application in simultaneous detection of Fe²⁺ and Fe³⁺.

Keywords: Composite nanomaterials; Fe(2+); Fe(3+); Simultaneous detection; Speciation.