A simple strategy for signal amplification based on DNA hybridization chain reaction for thrombin detection

A simple signal amplification strategy based on DNA hybridization chain reaction for the detection of thrombin was developed. Two conjugates based on gold nanoparticles were used. The first conjugates (Ap1-GNP-HRP) were prepared by functionalizing gold nanoparticles with thrombin aptamer 1 (Ap1) and horseradish peroxidase. They were immobilized on the electrode surface through a sandwich type reaction. The second conjugates (LDNA-GNP-HRP) were prepared by functionalizing gold nanoparticles by linking DNA (LDNA) and horseradish peroxidase. They were immobilized on the electrode surface through hybridization chain reaction. These two ways of introducing numerous HRPs onto the surface of the electrode resulted in significantly amplified electrochemical signal. Using the proposed strategy, we detected thrombin within the range from 0.001 to 20 nM with a detection limit of 0.6 pM based on S/N = 3. The proposed aptasensor had a good specificity and reproducibility. Moreover, the detection strategy could be easily extended to the detection of other biomolecules.