Dual-mode amplified detection of rabies virus oligonucleotide via Y-shaped DNA assembly

An innovative fluorescent and colorimetric dual-mode strategy based on Y-shaped DNA was proposed for the detection of rabies virus oligonucleotide. The cascade assembly of hairpin probes was initiated by the target, leading to the formation of Y-shaped DNA accompanied by freeing target to catalyze the next assembly process. The fluorescence recovery of the fluorophore FAM was accompanied by opening of hairpin probe. A colorimetric signal was generated by the proximity of glucose oxidase (GOx) and horseradish peroxidase (HRP), which was reflected by enhanced catalytic capability to TMB. Using this method, target DNA can be detected with a wide linear range from 0.1 to 6 nM with a detection limit of 15 pM, and from 0.5 to 60 nM with a detection limit of 60 pM for fluorescent and colorimetric readout, respectively. Moreover, the dual-mode detection strategy exhibited excellent selectivity towards the target compared with interference oligonucleotides. In addition, recoveries ranging from 96.0% to 106% with RSD values varying from 3.2% to 5.4%, and from 91.0% to 102% with RSD values varying from 3.3% to 7.1% for fluorescent and colorimetric studies, respectively, were obtained in diluted cerebrospinal fluid samples. The proposed dual-mode sensor is easy to operate with excellent detection performance. It would be superior to single mode detection and more practicable for quantitative detection of nucleic acid-related biomarkers due to the self-correction capability.