Biolayer interferometry

Concepcion J, Witte K, Wartchow C et al (2009) Label-free detection of biomolecular interactions using biolayer interferometry for kinetic characterization. Comb Chem High Throughput Screen 12 791-800... 

Inhibition of Chemokine Binding to GAGs by Biolayer Interferometry (BLI)... 

HS is a GAG naturally expressed by mammalian cells and is therefore more representative of physiological GAGs that immobilize chemokines than heparin. It is commercially available as a sodium salt isolated from kidney extract. We report here the biotinylation of HS and its use in a biolayer interferometry (BLI) assay to monitor the binding of monoclonal antibodies to their chemokine target displayed on HS (Fig. 2). This assay has also been used successfully with chemokine-binding proteins. 

Figures Inhibition of chemokine binding to heparan sulfate by biolayer interferometry. Upper panel example of the signals obtained with various inhibitorrchemokine ratios. Lower panel linear regression analysis of the response obtained by biolayer interferometry as a function of the percentage of unbound chemokine, indicating that the antibody prevents the interaction of the chemokine with GAGs.

Independent confirmation of primary hits is performed by a variety of reliable secondary assays. We use a number of direct binding assays such as biolayer interferometry (BLI) or (for strongly binding inhibitors) ITC as well as indirect binding assays such as thermal shift assays for hit validation. 

SPR (surface plasmon resonance) has gained widespread popularity due to the fact that it can provide quantitative binding information in a high-throughput manner [44]. It can also measure the kinetics of binding, which can be useful in lead optimization [45]. However, it is best paired with another screening technique to weed out false positives - a practice that should be applied to any method described here whenever possible [46], Screening methods based on biolayer interferometry can be used to the same effect as SPR [47]. 

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