Figure 1.

Schematic illustration of the DMR detection principle (adapted from Schröder et al.³¹). (A) Cells are grown in microplates that contain a resonant waveguide grating biosensor within the bottom of each well. The biosensor is illuminated by a broadband light source and the wavelength that is in resonance with the system is propagated and reflected. The resonance wavelength is a function of the refractive index near the surface of the biosensor. Stimulation of the cells can lead to a dynamic mass redistribution (DMR) of cellular constituents and subsequently a change in refractive index. This leads to a shift of the resonant wavelength in the pm range (Δλ), representing the readout of the DMR assay. (B) DMR that increases the optical density in proximity to the sensor surface results in a positive signal (P-DMR), whereas a decrease in optical density results in a negative signal (N-DMR), relative to the baseline³¹.