Electrostatic association complex of a polymer capped CdTe(S) quantum dot and a small molecule dye as a robust ratiometric fluorescence probe of copper ions

A ratiometric fluorescence probe for robust and rapid Cu 2+ detection was established based on an electrostatic association complex of polyallylamine capped CdTe(S) quantum dots (CdTe(S)@PAI QDs) and a small molecule dye 5-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-7-carboxylic acid (TPCA). Both of the components are easy to make. Strongly fluorescent CdTe(S)@PAI QDs could be simply prepared through a one-step UV irradiation while TPCA could be obtained directly through the hydrothermal method . The ratiometric probe was built through mixing of both components, neither organic solvent nor other harsh conditions is involved. The as-prepared probe shows dual-emission at 525 nm and 420 nm under excitation wavelength of 350 nm. The fluorescence ratio ( I 525nm /I 420nm ) remains constant with concentration changes of the complex up to ± 20% and a temperature variation from 20 to 50 °C, but shows significant change in the presence of Cu 2+ . The proposed probe exhibits excellent selectivity and sensitivity for Cu 2+ . The fluorescence ratio ( I 525nm /I 420nm ) show good linear relationship with the Cu 2+ concentration range from 0.05 to 1.6 μM and the limit of detection (S/N = 3) can reach 24 nM . Its applicability was demonstrated by detecting Cu 2+ ions in certified reference materials and real samples with recoveries in a range of 91.0–107.3%.