Backscattering Interferometry for Low Sample Consumption Molecular Interaction Screening

Backscattering interferometry (BSI), which uses a simple optical train comprising a He–Ne laser, a microfluidic channel, and a position sensor, has now enabled the measurement of both tethered and free-solution, label-free, molecular interactions within just nanoliters of sample. The simple macro-to-micro interface allows for a highly efficient assay work flow, which has been used to interrogate molecular binding interactions between proteins, ions and protein, and small molecules and proteins, with a high dynamic range of dissociation constants (KD) and unmatched sensitivity. With this technique, the equilibrium KD for several different binding partners was determined, typically using just picomole–micromole quantities of the binding pair at physiologically relevant concentrations.