ovalbumin and cadmium-telluride

Chemically denatured ovalbumin (dOB) was used to modify the surface of 3-mercaptopropionic acid (MPA) stabilized CdTe quantum dots (QDs), which resulted in a great enhancement of the synchronous fluorescence intensity. Moreover, dOB shell layer can effectively prevent the binding of other cations onto the QDs core and enhance the selective binding ability of Hg(2+) to dOB coated CdTe QDs (CdTe-dOB QDs). A simple method with high sensitivity and selectivity was developed for the determination of Hg(2+) with the CdTe-dOB QDs as fluorescence probe based on the merits of synchronous fluorescence spectroscopy (SFS). When scanning with excitation and emission wavelengths of 250 nm and 470 nm (Δλ=λ(em)-λ(ex)=220 nm), respectively, the maximum synchronous fluorescence peak of the CdTe-dOB QDs was located at 328 nm. Under optimal conditions, the change of the synchronous fluorescence intensity was in good linear relationship with the Hg(2+) concentration in the range of 0.08×10(-7) to 30.0×10(-7) mol L(-1) and the detection limit was 4.2×10(-9) mol L(-1) (S/N=3). The relative standard deviation of seven replicate measurements for the concentration of 2.0×10(-7) mol L(-1) and 20.0×10(-7) mol L(-1) were 2.8% and 2.3%, respectively. Compared with general fluorescence methods, the proposed method, which combined the advantages of high sensitivity of synchronous fluorescence and specific response of Hg(2+) to CdTe-dOB, had a wider linear range and higher sensitivity. Furthermore, the proposed method was applied to the determination of trace Hg(2+) in water samples with satisfactory results.

Topics: Cadmium Compounds; Fluorescent Dyes; Hydrogen-Ion Concentration; Mercury; Ovalbumin; Protein Denaturation; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Water

Water-soluble CdTe quantum dots (QDs) and their conjugates with antibodies and antigenes were prepared by optimized procedures for applications in CE immunoassays. The QD size of 3.5 nm, excitation spectrum in the range of 300-500 nm, the maximum wavelength of the emission spectrum at 610 nm, quantum yield of 0.25 and luminescence lifetimes in the range of 3.6-43 ns were determined. The 0.1 M solution of TRIS/TAPS (pH 8.3) was found to be the optimum buffer for the separation of the antiovalbumin-ovalbumin immunocomplex from the free conjugates of QDs.

Topics: Cadmium Compounds; Electrophoresis, Capillary; Immunoassay; Luminescent Measurements; Ovalbumin; Particle Size; Quantum Dots; Tellurium