One-pot synthesis of novel water-dispersible fluorescent silicon nanoparticles for selective Cr2O72− sensing

Abstract

Chromium (Cr(VI)), a highly toxic metal-oxyanion which is carcinogenic and mutagenic to humans, is a severe environmental pollutant. Developing simple methods for sensitive and selective detection of Cr(VI) is of great significance. In this work, fluorescent silicon nanoparticles (SiNPs) with good water solubility were facilely synthesized via a one-step hydrothermal method by using (3-aminopropyl)triethoxysilane (APTES) as the silicon source and natural antioxidant quercetin as the reducing agent. The obtained SiNPs displayed good thermostability, salt-tolerance and photo-stability. The as-prepared SiNPs exhibited bright blue emission at 437 nm under excitation at 362 nm, allowing them to be developed as a fluorescent probe for detection of Cr₂O₇²⁻. Significantly, the fluorescence of the SiNPs could be remarkably quenched by Cr₂O₇²⁻via the internal filtering effect (IFE). Based on this phenomenon, a novel fluorescence method for detection of Cr₂O₇²⁻ was established. A good linear relationship was obtained from 0.5 to 100 μM with a limit of detection (based on 3 s/k, LOD) of 180 nM. The proposed fluorescence method was successfully applied to the detection of Cr₂O₇²⁻ in tap water. Moreover, a fluorescent filter paper sensor was developed for the visual detection of Cr₂O₇²⁻, providing a valuable platform for Cr₂O₇²⁻ sensing in a convenient way.