A colorimetric biosensor for ultrasensitive detection of the gene based on a dual DNA-induced cascade hybridization reaction.

In this work, a simple and ultrasensitive colorimetric biosensor for detection of gene fragments (Leigh syndrome) has been developed based on a dual DNA-induced cascade hybridization reaction. Firstly, a biotin labeled capture probe was immobilized on a streptavidin labeled 96-well transparent plate surface. Then the target fragment and auxiliary probe S1 were added into the reaction system to form a "Y" structure with the capture probe. Furthermore, to achieve a highly efficient signal amplification strategy, digoxin labeled P1, P2, P3 and P4 probes were used to cause a dual DNA-induced cascade hybridization reaction on the "Y" structure of the 96-well plate surface. As a detection probe, the HRP anti-digoxin antibody was combined on the surface to produce a colorimetric response to the fragment in the presence of TMB. Under the optimal conditions, the established method exhibited a wide linear range from 1.0 × 10 M to 1.0 × 10 M and a detection limit to as low as 1.73 × 10 M. In addition, the strategy has been successfully applied to the detection of in spiked human serum samples. Therefore, the established biosensor has potential application prospects in gene fragment analysis and early diagnosis of clinical diseases.