Figure 1: Setup and principle of MST.
From: Protein-binding assays in biological liquids using microscale thermophoresis
(a) Experimental approach. With an additional dichroic mirror inserted into an epifluorescence microscope, a heating infrared-laser is focused into a fused silica capillary with an inner diameter of 100 μm. The sample fluorescence is imaged with a CCD camera. (b) Fluorescence images. Fluorescence images are acquired over time. Initially, fluorescently labelled molecules are distributed evenly. After switching on the heating with a focused infrared-laser, the molecules experience the thermophoretic force in the temperature gradient and typically move out of the heated spot. In the steady state, this molecule flow is counterbalanced by ordinary mass diffusion and a steady-state concentration profile is established. The colour code indicates the relative fluorescence in the sample. (c) Steady-state profiles. The steady-state profiles of human interferon-γ are plotted for various concentrations of a binding antibody (black ×: 0.1 nM, red plus sign: 80 nM, blue number sign: 500 nM). The depletion directly reflects the fraction of bound complex.
