Fluorescence polarization gene assay for HIV-DNA based on the use of dendrite-modified gold nanoparticles acting as signal amplifiers

The authors describe a fluorescence polarization assay for HIV-DNA. It is based on the use of gold nanoparticles (AuNPs) modified with DNA dendritic macromolecules that act as signal amplifiers. In the presence of HIV-DNA, the AuNP-DNA dendritic macromolecules and fluorescently labeled DNA probe combine with HIV-DNA in a sandwich format to form a conjugate. This reaction slows down the rotational speed of the labeled DNA probe because of the increase of molecular weight and volume. This increases fluorescence polarization and the sensitivity of the system. The relative fluorescence polarization values increase linearly in the 150 pM to 6 nM HIV-DNA concentration range, with a 73 pM detection limit. The results show this amplification strategy to be most useful for ultrasensitive determination of oligonucleotides by means of fluorescence polarization. Graphical abstract Schematic of a novel fluorescence polarization assay for the HIV-DNA. Ultrasensitive detection is accomplished by using AuNP-DNA dendritic macromolecules as signal amplification factor.