Surface Plasmon Resonance Imaging-Mass Spectrometry Coupling on Antibody Array Biochip: Multiplex Monitoring of Biomolecular Interactions and On-Chip Identification of Captured Antigen

The coupling of surface plasmon resonance imaging (SPRi) with mass spectrometry (MS) offers a very promising multidimensional analysis. This system takes advantage of the two well-established techniques: SPR, which allows for the analysis of biomolecular interactions through the determination of kinetic and thermodynamic constants, and MS, which can characterize biological structures from mass measurements and fragmentation experiments. Here, a protocol for the coupling of SPRi with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is described using a biochip grafted by antibodies in an array format. Interaction between β-lactoglobulin antibodies and the protein antigen is detected and analyzed by SPRi. Then, the arrayed biochip which fitted a commercially MALDI target was inserted in a MALDI source, and mass spectra were recorded directly from the biochip surface from each antibody spot, showing protein ions attributed to the corresponding specific protein antigens.