A fluorescent aptasensor for analysis of adenosine triphosphate based on aptamer-magnetic nanoparticles and its single-stranded complementary DNA labeled carbon dots

A new fluorimetric aptasensor was designed for the determination of adenosine triphosphate (ATP) based on magnetic nanoparticles (MNPs) and carbon dots (CDs). In this analytical strategy, an ATP aptamer was conjugated on MNPs and a complementary strand of the aptamer (CS) was labeled with CDs. The aptamer and its CS were hybridized to form a double helical structure. The hybridized aptamers could be used for the specific recognition of ATP in a biological complex matrix using a strong magnetic field to remove the interfering effect. In the absence of ATP, no CDs-CS could be released into the solution and this resulted in a weak fluorescence signal. In the presence of ATP, the target binds to its aptamer and causes the dissociation of the double helical structure and liberation of the CS, such that a strong fluorescence signal was generated. The increased fluorescence signal was proportional to ATP concentration. The limit of detection was estimated to be 1.0 pmol L-1 with a dynamic range of 3.0 pmol L-1 to 5.0 nmol L-1. The specific aptasensor was applied to detect ATP in human serum samples with satisfactory results. Moreover, molecular dynamic simulation (MDS) studies were used to analyze interactions of the ATP molecule with the aptamer.