CdTe quantum dot-based fluorescent probes for selective detection of Hg (II): The effect of particle size

Mercury ions-induced fluorescence quenching properties of CdTe quantum dots (QDs) have been studied using the fluorescence spectroscopic techniques. By using the hydrothermal method, the CdTe QDs with different particles sizes from 1.98 to 3.68nm have been prepared, and the corresponding fluorescence emission wavelength is changed from 518 to 620nm. The fluorescence of QDs is enhanced after linking Bovine serum albumin (BSA) onto the surface of the QDs. Experimental results show that the fluorescence intensity of BSA-coated CdTe QDs could be effectively quenched when Hg²⁺ react with BSA-coated CdTe QDs. Interestingly, both the sensing sensitivity and selectivity of this fluorescence probe could be improved when the particle size of the QDs decreases. Thus the BSA-coated CdTe QDs with green fluorescence emission have better advantages than the BSA-coated CdTe QDs with red fluorescence for Hg²⁺ detection. Interference experiment results indicate that the influence from other metal ions could be neglected in the detection, and the Hg²⁺ could be specifically detected. By using this BSA-coated CdTe QDs-based fluorescence probe, the Hg²⁺ could be detected with an ultra-low detection limit of nanomole level, and the linear range spans a scope from 0.001 to 1μmol/L.