Synthesis and characterization of multifunctional CdTe/Fe2O3@SiO2 core/shell nanosensors for Hg2+ ions detection

Abstract

Novel multifunctional magnetic-photoluminescent Hg²⁺ ion sensing nanocomposites were developed by applying SiO₂ as the encapsulation agent to package Fe₂O₃ NRs and CdTe QDs, resulting in CdTe/Fe₂O₃@SiO₂ core/shell nanostructures. The core/shell structural nanocomposites were confirmed by field-emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDXA), X-ray diffraction (XRD) patterns, high-resolution transmission electron microscopy (HRTEM) and selective-area electron diffraction (SAED) patterns. Photoluminescence (PL) spectroscopy and superconducting quantum interference device (SQUID) were used to investigate the optical and magnetic properties of the core/shell structural nanocomposites, respectively. The fluorescence of the obtained nanocomposites could be quenched effectively by Hg²⁺ ions without obvious changes of spectral widths and optical shift of PL emission. The quenching mechanism was studied and the results showed the existence of both static and dynamic quenching processes. The modified Stern–Volmer equation showed a linear response in the range of 1 to 10 μM with a quenching constant (K_sv) of 3.5 × 10⁴ M⁻¹. This hydrophilic, biocompatible, multifunctional, easy to separate and sensitive fluorescence nanosensor may find applications in Hg²⁺ ion determination in the biological and environmental areas.