Mass-amplifying quantum dots in a fluorescence polarization-based aptasensor for ATP

We report on a fluorescence polarization assay for the detection of the target analyte ATP by making use of an aptasensor and of mass-amplifying CdTe-CdS quantum dots. The ATP aptamer was modified with digoxin antigen and hybridized with its complementary DNA that was modified with the CdTe-CdS quantum dots. Following the addition of digoxin antibody, the mass-amplifying aptasensor probe is formed as a result of the immuno reaction. In the presence of ATP, the polarization of fluorescence decreases because the digoxin antibody becomes dissociated due to the recognition of the ATP by the ATP aptamer. Under optimized conditions, the method has a linear response to ATP in the 10 to 350 mu M concentration range, and the limit of detection is 3.7 mu M. The method combines the specific recognition capability of aptamers with the sensitivity of an immunoreaction. It has good selectivity and sensitivity, and can be used to detect ATP in serum samples.