Water-soluble and luminescent ZnO quantum dots (QDs) capped by (3-aminopropyl) triethoxysilane
(APTES) are environment-friendly with strong photoluminescence (max. wavelength: 530 nm). Inter-
estingly, it was found that the fluorescence could be quenched by dopamine (DA) directly. On the basis
of above, a novel ZnO QDs based fluorescent probe has been successfully designed to detect DA with
high selectivity and sensitivity. Moreover, the possible fluorescence quenching mechanism was
proposed, which showed that the quenching effect may be caused by the electron transfer from ZnO
QDs to oxidized dopamine–quinone. Under optimum conditions, the relative fluorescence intensity was
linearly proportional to the concentration of DA within the range from 0.05 to 10 mM, with the
detection limit down to 12 nM (n¼3). Also, the selectivity experiment indicated the probe had a high
selectivity for DA over a number of possible interfering species. Finally, this method was successfully
used to detect DA in serum samples with quantitative recoveries (99–110%). With excellent selectivity
and high sensitivity, it is believed that the ZnO QDs based fluorescent probe has a potential for the
practical application in clinical analysis.