Octopus-like DNA nanostructure coupled with graphene oxide enhanced fluorescence anisotropy for hepatitis B virus DNA detection

Fluorescence Anisotropy (FA) is an effective biochemical detection method based on molecular rotations. Graphene oxide (GO) has been extensively used as an FA amplifier. However, the enhancement of FA by GO alone is limited and the strong scattering of GO will easily make the measurement of FA inaccurate. In order to address these problems, an octopus-like DNA nanostructure (ODN) was designed and coupled with GO to enhance the FA together in this work. By mimicking the multi-clawed structure of the octopus, the ODN can be adsorbed on GO tightly, which not only could improve the sensitivity because of the double FA enhancement abilities of GO and ODN, but also could improve the specificity due to the decrease of the nonspecific interaction in complex samples. Furthermore, ODN could maintain a certain distance between the fluorophore and GO to reduce the fluorescence quenching efficiency of GO, which could improve the accuracy. This method has been applied for the detection of hepatitis B virus DNA (HBV-DNA) in a range of 1-50 nmol/L and the limit of detection (LOD) was 330 pmol/L. In addition, the proposed method has been successfully utilized to detect HBV-DNA in human serum, indicating that this method has a great practical application prospect.