Aptameric molecular switch for cascade signal amplification.

BACKGROUND: High sensitivity of analysis is constantly in demand in biomedical research and clinical diagnosis. In recent years aptamer-based analytical methods have been developed for protein detection. We developed a cascade signal amplification strategy based on molecular switches and aptamers to improve protein detection. METHODS: Our cascade signal amplification strategy based on molecular switches and aptamers consisted of 2 steps, including the recognition and the triggering of a polymerase reaction. The procedure was designed to simplify the analysis by detecting trace amounts of target isothermally, in real time, and in a homogeneous solution. We applied this method to measure thrombin in human serum samples. RESULTS: This cascade signal amplification strategy exhibited a linear response in thrombin concentration from 0.3 to 10 nmol/L, with a detection limit of 1.7 × 10(-10) mol/L within 60 min. Results of the analysis of thrombin in human serum diluted 1:1 appeared to be linear, as was observed in buffer, in the tested concentration range of 0.3-10 nmol/L. CONCLUSIONS: The aptameric sensor provides promising potential for detecting and screening trace concentrations of biomarkers in complex matrices for clinical applications.