Monday, 21 July, 2014
Thermophoresis in Nanoliter Droplets to Quantify Aptamer Binding
S. Seidel, N. Markwardt, S. Lanzmich, and D. Braun -
Angew. Chem. Int. Edition, Vol. 53 (30), pp 79487951 (2014)
Biomolecule interactions are central to pharmacology and diagnostics. These interactions can be quantified by thermophoresis, the directed molecule movement along a temperature gradient. It is sensitive to binding induced changes in size, charge, or conformation. Established capillary measurements require at least 0.5L per sample. We cut down sample consumption by a factor of 50, using 10nL droplets produced with acoustic droplet robotics (Labcyte). Droplets were stabilized in an oilsurfactant mix and locally heated with an IR laser. Temperature increase, Marangoni flow, and concentration distribution were analyzed by fluorescence microscopy and numerical simulation. In 10nL droplets, we quantified AMP-aptamer affinity, cooperativity, and buffer dependence. Miniaturization and the 1536-well plate format make the method high-throughput and automation friendly. This promotes innovative applications for diagnostic assays in human serum or label-free drug discovery screening.