A bicyclo-hairpin probe mediated strand displacement amplification strategy for label-free and sensitive detection of bleomycin

Monitoring of bleomycin concentration is critical in clinical therapy. Here, a bicyclo-hairpin probe mediated strand displacement amplification strategy was developed for bleomycin detection. Firstly, bleomycin cleaved bicyclo-hairpin probe to release a trigger sequence. Then the trigger sequence initiated strand displacement amplification reaction to produce numerous G-quadruplex forming sequences. Finally, G-quadruplexes bound with N-methyl mesoporphyrin IX molecules and an enhanced fluorescent signal could be detected. In this strategy, a bicyclo-hairpin probe was ingeniously designed for bleomycin detection, which could silence the trigger sequence to reduce non-specific hybridization of detection method. In addition, based on bleomycin-induced DNA scission, a label-free fluorescent sensor for bleomycin detection was established. Our strategy could determine bleomycin sensitively with a detection limit of 0.34 nM. Fluorescent response of detection system toward four different anti-tumor drugs proved that this strategy had admirable selectivity. Satisfactory recoveries in human serum samples revealed that our method had a great potential in real sample assay.