Enzyme-free signal amplified Au nanoparticle fluorescence detection of thrombin via target-triggered catalytic hairpin assembly

摘要

Herein, we proposed an enzyme-free target-triggered catalytic hairpin assembly (CHA) for signal amplified fluorescence thrombin detection. In the detection system, two hairpin oligonucleotides (HP1, HP2) were used. The HP1 containing complimentary units forms a closed stem structure which brings the fluorescein (FAM) near the gold nanoparticle (AuNP) surface where they will be quenched. Upon addition of thrombin, the CHA could be initiated to form HP1-HP2-thrombin complex, which then through strand displacement process, the complex transforms into double-strand HP1-HP2 with a rod-like structure with the release of thrombin and also sequestering fluorophore from quencher surface, resulting in fluorescence recovery. The released thrombin further participated in subsequent reaction cycles, hence, the signal of the detection system significantly amplified. The method showed a limit of detection (LOD) of 165 pM with a linear range from 0.2 to 100 nM. The proposed method could be used as a potential application in complex biological matrices.