Optical waveguide-based biosensor for label-free monitoring of living cells

Here, we briefly discuss the past, present, and possible future of label-free optical biosensors in cell research, especially focusing on the kinetic monitoring of cellular adhesion. Currently available optical biosensors possess outstanding potentials still not rightfully recognized and still waiting to be fully exploited in the field of cell science. Thus, during the description we give special emphasis to the advantages that the state-of-the-art optical cell-based biosensors possess as compared to microscope- or force measurement-based techniques widely used to characterize cell adhesion. To name here only a few, they enable label-free detection close to a planar sensor surface, have high sensitivity, and generate superior quality kinetic data. Such information-rich kinetic data, in turn, can be analyzed in-depth and comparatively. To exemplify the importance of in-depth kinetic analysis, we review a recent study, in which the Epic BenchTop high-throughput optical biosensor was used to measure the dependence of cancer cell adhesion kinetics on the surface density of integrin ligands. Based on the kinetic data, a model enabling the label-free determination of the dissociation constant of the adhesion ligands bound to their native cell membrane receptors has been constructed. As an outlook, the perspectives of the technology is briefly discussed