Ultrasensitive atomic fluorescence spectrometric detection of DNA with quantum dot-assemblies as signal amplification labels

Abstract

Hydride generation atomic fluorescence spectrometry (HG-AFS) has been widely used for highly sensitive determination of more than 10 elements that are capable of hydride generation in geological, environmental and biological samples, but its bioanalytical potential has not been well-exploited yet. With CdS quantum dots (QDs) as both the signal labels for DNA sandwiching and analytes for HG-AFS (acid-released Cd²⁺ from QDs), here we proposed an ultrasensitive indirect method for HIV DNA analysis by HG-AFS. After a conventional sandwich-type hybridization reaction between capture DNA, target DNA and signal DNA labelled with CdS QD assembled silica microspheres, nitric acid was added to dissolve QDs and release Cd²⁺ from the QD-labels, which were then detected by HG-AFS. This efficient signal amplification strategy, coupled with the highly sensitive HG-AFS detection, gave rise to an impressive limit of detection of 0.8 aM and a wide dynamic concentration range (1 aM to 1 fM). This HG-AFS-based DNA biosensing platform holds great promise in future tumor marker detection and early cancerous diseases diagnosis.