Abstract
We presented a new strategy for ultrasensitive detection of DNA sequences based on the novel detection probe which was labeled with Ag+ using metallothionein (MT) as a bridge. The assay relied on a sandwich-type DNA hybridization in which the DNA targets were first hybridized to the captured oligonucleotide probes immobilized on Fe3O4@Au composite magnetic nanoparticles (MNPs), and then the Ag+-modified detection probes were used to monitor the presence of the specific DNA targets. After being anchored on the hybrids, Ag+ was released down through acidic treatment and sensitively determined by a coupling flow injection–chemiluminescent reaction system (Ag+–Mn2+–K2S2O8–H3PO4–luminol) (FI–CL). The experiment results showed that the CL intensities increased linearly with the concentrations of DNA targets in the range from 10 to 500pmolL−1 with a detection limit of 3.3pmolL−1. The high sensitivity in this work may be ascribed to the high molar ratio of Ag+–MT, the sensitive determination of Ag+ by the coupling FI–CL reaction system and the perfect magnetic separation based on Fe3O4@Au composite MNPs. Moreover, the proposed strategy exhibited excellent selectivity against the mismatched DNA sequences and could be applied to real samples analysis.
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