Silica nanoparticles based label-free aptamer hybridization for ATP detection using hoechst33258 as the signal reporter

In this work, we have developed a simple and sensitive method for ATP detection using silica nanoparticles (NPs) as the platform and hoechst33258 as the signal reporter. The ATP-binding aptamers hybridize with the probe DNA (DNAp) immobilized NPs to form the aptamer/DNAp duplex on the NPs surface. The conformational change of the aptamer leads to the decrease of the aptamer/DNAp duplex on the NPs due to the ATP-binding aptamer switches its structure from the aptamer/DNAp duplex to the aptamer/target complex in the presence of ATP. ATP detection can be easily realized by separating the silica nanoparticles and adding the hoechst33258 of intercalating to aptamer/DNAp (dsDNA). Good selectivity between ATP and CTP, GTP or UTP has been demonstrated, which is due to the specific recognition between ATP aptamer and ATP. The Kd was estimated to be ∼1 mM from 0 to 4 mM and a liner response was observed from 0 to 0.2 mM with a detection limit of ∼20 μM. Compared with other methods, the carboxyl-modified silica nanoparticles (∼60 nm) prepared by the reverse microemulsion method can serve as a stable and sensitive sensor platform because of their smaller size and facile conjugation with amine-containing molecules. In addition, the high sensitivity and selectivity of hoechst33258 was employed for the ssDNA and dsDNA determination, which takes advantage of the label-free aptamer and lower cost.