Cadmium Tellurium Quantum Dots in Sol-Gel-Derived Silica Spheres Coated with Calix[6]Arene as an Optical Probe for Dalapon

This paper reports a new optical probe for detect dalapon. We have synthesized the luminescent and stable CdTe quantum dots(QDs) capped with calix[6]arene(C[6]/SiO2/CdTe) via the sol-gel technique in aqueous media. These hybrid organic-inorganic compounds are characterized by IR spectroscopy, ultraviolet-visible spectroscopy (UV-vis), transmission electron microscopy (TEM), and fluorescence. We found that the C[6]/SiO2/CdTe were more stable and had higher fluorescence than the SiO2/CdTe nanoparticles (NPs). The C[6]/SiO2/CdTe show selectivity and sensitivity to dalapon via significant fluorescence intensity decrease. It can be ascribed to the Stern-Volmer equation. Under the optimal conditions, the relative fluorescent intensity was decreased linearly with increasing dalapon concentration in the range of 1.0–25.0 nmol/L with a detection limit of 0.262 nmol/L of dalapon. The possible underlying mechanism is discussed by Langmuir binding isotherm.