A novel fluorescent probe for adenosine 5′-triphosphate detection based on Zn2+-modulated l-cysteine capped CdTe quantum dots

In this work, we have designed a simple and sensitive fluorescence probe for adenosine 5′-triphosphate (ATP) detection. A series of l -cysteine capped CdTe quantum dots (QDs) with different sizes were synthesized in aqueous phase. The effects of Zn2+ on different sizes of l -cysteine capped CdTe QDs were investigated and the fluorescence of CdTe with small size QDs could be effectively quenched due to the binding of Zn2+ to the l -cysteine on the surface of the QDs and the electron transfer from the photoexcited QDs to Zn2+. The phosphate groups of ATP have a high affinity for zinc ions through Zn O P bonds, with the addition of ATP, Zn2+ could bind with ATP based on the metal–ligand coordinative effect and the modulation of Zn2+ to CdTe QDs would be inhibited. Hence the quenched fluorescence of the CdTe QDs can be recovered. The recovered fluorescence of QDs was proportional to the concentration of ATP in the range of 5–50 μmol L−1 and the detection limit for ATP was 2.07 μmol L−1. The proposed sensing assay showed a good selectivity for ATP over other biologically important phosphates, and it was applied to the determination of ATP in human serum sample with satisfactory results.