A novel core-satellite CdTe/Silica/Au NCs hybrid sphere as dual-emission ratiometric fluorescent probe for Cu2+

• A novel core-satellite CdTe/Silica/Au NCs hybrid sphere was successfully fabricated.
• The hybrid spheres have been developed as a ratiometric fluorescence probe.
• The ratiometric fluorescent probe was applied in the determination of Cu2+ in vegetable samples.

Herein, we synthesized a novel core-satellite CdTe/Silica/Au NCs hybrid sphere by covalently linking the separately synthesized highly fluorescent bovine serum albumin (BSA) stabilized gold nanoclusters (Au@BSA NCs) to the surface of the amino functionalized CdTe@SiO2 spheres by using the EDC chemistry. Numerous “satellites” of Au NCs were linked on the surface of the CdTe@SiO2 by the way of amide bonding. The synthesized dual-emission hybrid spheres were further characterized by the transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), UV–vis absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy, photoluminescence (PL), etc. Finally, the CdTe/Silica/Au NCs hybrid spheres were developed as ratiometric fluorescence probe for the determination of Cu2+ with high sensitivity and selectivity. The fluorescence intensity ratio (F545 nm/F655 nm) of the probe against the concentration of Cu2+ showed a good linear relationship from 6.0×10−7 mol L−1 to 100.0×10−7 mol L−1. It showed an excellent reproducibility (0.67% relative standard deviation for 10 replicate measurements of Cu2+ at 40.0×10−7 mol L−1) and low detection limit (4.1×10−7 mol L−1). Furthermore, the ratiometric fluorescent probe was successfully applied in the determination of Cu2+ in vegetable samples with satisfactory results.