Reducing Measurement Deviation by Metastable DNA Probes for Aptamer Thermodynamic Characterization.

DNA reaction equilibrium-based calculations have great potential in thermodynamic characterization, but their widespread applications are hindered by significant measurement deviation of equilibrium concentration. Here, we report the advantages of metastable DNA hybridization in reducing quantification deviation of equilibrium concentration and propose a universal and standardized strategy for measuring aptamer binding energy, termed metastable DNA reference calorimetry (MDRC). We built different MDRC-based algorithms tailored to different aptamer binding models, enabling the calculation of thermodynamic parameters for aptamers with one or more binding sites. Our correlative model, considering the cross-effects between different binding sites, showed that for ATP aptamers with two binding sites, binding of the first ATP molecule would decrease its affinity for the second at low temperatures and even completely inhibit this binding at high temperatures. Moreover, the thermodynamic parameters of protein-specific aptamers were calculated to elucidate the universality of the method. The successful analysis of cell-specific aptamers further demonstrated MDRC's applicability in complex biological systems.