A label-free biosensor-based cell attachment assay for characterization of cell surface molecules

A photonic crystal optical biosensor is incorporated into standard format 96-well microplates for the purpose of detecting the attachment of cells to the biosensor surface without the use of fluorescent labels or any other type of marker. We show that the attachment of cells to the biosensor can be modulated by the immobilization of cognizant ligands to the sensor surface that selectively recognize expressed outer membrane proteins. Jurkat T cells were used as a model system for demonstrating the biosensor-based assay. The attachment of two Jurkat cell lines were compared versus surface-immobilized monoclonal antibodies, where the expression level of cell surface antigens correlated well with the level of cell attachment to sensors with the corresponding antibody. The biosensor system was able to distinguish nearly identical Jurkat cell lines, which only differed by the presence of one expressed surface marker. These results suggest that the biosensor detection system can be used to identify cell surface molecules and to screen ligands that interact with cell surface molecules.