Direct Detection of Low-Molecular-Weight Compounds in 2D and 3D Aptasensors by Biolayer Interferometry

The direct biolayer interferometry (BLI) measurement of low-molecular-weight (LMW) analytes (<200 Da) still represents a challenge, in particular, when low receptor densities are used. BLI is a powerful optical technique for the label-free, real-time characterization and quantification of biomolecular interactions at interfaces. We demonstrate herein that the quantification of biomolecular recognition is possible by BLI using either 2D-like or 3D platforms for aptamer ligand immobilization. The influence of the aptamer density on the interaction was evaluated and compared for the two sensor architectures. Despite the LMW of the analyte, BLI monitoring led to signals that are exploitable for affinity and kinetic studies, even at low aptamer density. We demonstrate that the immobilization format as well as the aptamer density has a crucial influence on the determination of the recognition parameters.