Real-time analysis of biomolecular interactions in Surface Plasmon Resonance imaging

Real time imaging of macro molecular interactions is a challenging issue in life science. Among different developed techniques, the emerging SPR (Surface Plasmon Resonance) approach is one of the most promising: no molecular labeling is necessary to reveal molecular interactions, especially since extension of microarray allow multiple interactions to be observed at the same time. Such a real time monitoring of various biomolecular interactions raises several challenges in terms of image segmentation of the spotted material, extraction and interpretation of the mean hybridization signal of each spot. This paper develops an automated approach for SPR image analysis tackling the above-mentioned issues. First, a spatio-temporal anisotropic filtering removes the random noise of large amplitude present in the SPR data. The pre-filtered signal supplies an image segmentation module in charge with the automated detection of the material deposited on the spots. Microarray spot segmentation is performed by combining advanced gray-level morphological operators and a priori knowledge on the spotting geometry. Non-uniform hybridization within a spot can thus be detected and the spot excluded from analysis. In the same manner, the presence of image artefacts (chip scratch, deposit leakage) can be notified during experimentation. The mean signal over each valid spot is then extracted and its temporal behavior provides the kinetic parameters characterizing the biological interaction (hybridization/dehybridization speed, end-point state). The preliminary results obtained on test biomolecular interactions confirmed our expectations in sensitivity improvement with respect to fluorescence-based techniques. A larger validation of the proposed approach in terms of maximum sensitivity allowed for biological interactions discrimination is currently in progress.