Dual-mode ultrasensitive detection of acute leukemia gene Pax-5a based on smart DNA programmed dendrimer

Accurate and sensitive detection of Pax-5a gene is the basis of early diagnosis and prediction of acute leukemia. This research aims to develop a universal dual-mode sensing method enables ultrasensitive gene detection based on smart control of DNA amplification by nucleic acid beacons e to form programmed dendrimer. The Pax-5a target gene triggers the opening of smart gate hairpin probe (Hp), exposing the stem sequence as the primer to bind with padlock probe for rolling circle amplification (RCA). The generated long strand RCA product contains a large number of functional regions that induce hybridization chain reaction (HCR) between two hairpin sequences and finally grow to form DNA dendrimer. For signal generation, the fluorescence sensing mode is based on the fluorescence recovery of the fluorophore during DNA dendrimer formation. The electrochemical sensing mode is based on the intercalation of electroactive methylene blue (MB) molecules into the DNA dendrimer which bind onto the electrode by capture probe. Comparing this novel approach to the conventional HCR and RCA, the signal can be enhanced multiple times. In addition, the dual-mode sensing strategy showed ultra-sensitivity, good selectivity, simple operation and could be used for complex substrate environment analysis offering a wide range of applications in clinical diagnosis and bioanalysis.