Electrochemical biosensing of DENV nucleic acid amplified with triplet nanostructure-mediated dendritic hybridization chain reaction

A universal and highly sensitive electrochemical biosensing strategy was developed by using a triplet nanostructure-mediated dendritic hybridization chain reaction (HCR) for the analysis of Dengue virus (DENV) nucleic acid. A locked dsDNA was firstly recognized by the target DENV nucleic acid fragment to release the initiator, which was then captured by a capture DNA modified gold electrode to initiate the HCR in the presence of biotin labeled substrates A and B, and two helpers. After the recognition reactions of the captured initiator with substrate A and then helper 1, one DNA structure was formed to react with substrate B, which produced a triplet nanostructure to trigger the dendritic HCR by the toehold of the hybridization structure. After the dendritic product was bound with avidin labeled horseradish peroxidase (avidin-HRP), an amperometric signal could be obtained to achieve ultrasensitive electrochemical detection of DENV. The non-enzymatic isothermal amplification was driven only by entropy. The stable three-dimensional dendritic nanostructure with rigid double helix could assure the excellent performance of the designed electrochemical biosensing strategy. The proposed method showed a detection range of 1.6-1000 pM with a detection limit of 188 fM and ability to distinguish single-base mutation. By changing the recognition sequence of the initiator, the detection of different DENV nucleic acid fragments could be achieved with the same performance. Thus, this method had good extendability for other nucleic acids, providing a promising candidate for nucleic acid detection in early clinical diagnosis.