Quantum dots and ionic liquid-sensitized effect as an efficient and green catalyst for the sensitive determination of glucose

• Introduce a novel catalyst for monitoring H2O2 and glucose in QDs-based fluorometric method.
• The use of ionic liquid/copper complex as an efficient and green catalyst.
• The determination of glucose in human serum and urine samples with low detection limit.
• The PL emission intensity of CdSe QDs increased in the presence of ionic liquid and ionic liquid/copper complex.

A novel fluorescence (FL) method using water-soluble CdSe quantum dots (QDs) is proposed for the fluorometric determination of hydrogen peroxide and glucose. Water-soluble CdSe QDs were synthesized by using thioglycolic acid as stabilizer in aqueous solutions. The nanoparticles were structurally and optically characterized by X-ray powder diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), UV–Vis absorption spectroscopy, photoluminescence (PL) emission spectroscopy and transmission electron microscope (TEM). Ionic liquid-sensitized effect in aqueous solution was then investigated. In the presence of ionic liquid as catalyst, H2O2 was decomposed into radical that could quench the fluorescence of CdSe QDs more efficiently and rapidly. Then the oxidization of glucose by glucose oxidase was coupled with the fluorescence quenching of CdSe QDs by H2O2 producer with ionic liquid catalyst, which can be used to detect glucose. Therefore, a new FL analysis system was developed for the determination of glucose. Under the optimum conditions, there is a good linear relationship between the relative PL emission intensity and the concentration of glucose in the range of 5.0 × 10−7–1.0 × 10−4 M of glucose with a correlation coefficient (R2) of 0.9973. The limit of detection of this system was found to be 1.0 × 10−7 M. This method is not only simple, sensitive and low cost, but also reliable for practical applications.

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