Future Trends in SPR Technology

Abstract

Krone et al. [3] first combined SPR and mass spectrometry (MS), which created a unique approach for protein investigations. This technique was adapted and modified in several laboratories [4][5][6][7] and some of the commercial instruments are now also equipped with basic analyte recovery capability for MS. The basic idea is to follow up the characterization of interactions between proteins and surface-immobilized ligands by SPR with the determination of the identity of the bound proteins or peptides using MS. This has applications in protein interaction discovery in proteomics, and also the characterization of protein modifications critical for the interaction. Considering the SPR sensor surface as a miniaturized chromatographic matrix, SPR-MS is reminiscent also of the traditional affinity chromatographic purification preceding MS in protein discovery, but obviously with added real-time quantification of the capturing and elution process, in addition to exhibiting different elution behavior due to the much smaller scale matrix. Several fundamentally different interface approaches have been developed by different groups, for example (1) direct use of the SPR chip surface for MS by mounting the preloaded SPR chip on a MALDI platform [3] or analyzing the surface with a SELDI protein chip reader [7]; (2) on-chip digestion followed by microfluidic elution, recovery in a reversed-phase microcapillary column and ESI-MS/MS sequencing of peptides from the digest [5]; and (3) analyte dissociation, microfluidic elution and collection followed by external digestion and MALDI-TOF sequencing [4,9]. Recent progress in SPR-MS includes improved methods and operations, increased limits of detection, multi-protein analysis and protein-complex delineation. With the subsequent design of SPR protein arrays, SPR-MS enters into the field of high-throughput protein interaction discovery and miniaturized diagnostics.Below we briefly highlight an example of SPR detection of an enrichment and elution process of specifically bound analyte as an application of SPR-MS by Visser et al. (Heck's group) at the University of Utrecht (The Netherlands) [8]. In this work, an SPR-based chemical proteomics approach in combination with nano-liquid chromatography/electrospray tandem mass spectrometry (nanoLC/ESI-MS/MS) was used to obtain both semi-quantitative and qualitative data on enriched proteins obtained from SPR sensor surfaces. The aim of the research was the characterization and identification of autoimmune antibody-antigen complexes present in RA patient sera. The autoimmune antibodies can be enriched using a citrullinated peptide (i.e. a specific peptide where the arginine is replaced by citrulline) as a ligand which is immobilized on a geltype G-COOH sp IBIS sensor chip. The work is connected to the research described in Chapter 7, which should be consulted for details and references. 357 Future Trends in SPR Technology

Surface Plasmon Resonance: A Versatile Technique for Biosensor Applications

“…SPR biosensors provide excellent analytical performance in terms of high sensitivity, fast response, LOD and reproducibility with its label-free, real-time approach. However, one challenge for SPR technology, which was raised in 2008 by Schasfoort and Schuck about its suitability for point-of-care (POC) diagnostics [ 139 ], has not been completely solved. The inherent drawback of SPR lies in the interference of non-specific bindings to the outcome signals.…”

Nitride-Based Microarray Biochips: A New Route of Plasmonic Imaging

“…The assay precision can be improved with specific strategies for signal sampling and data management . Note that the detecting wavelength (∼446 nm) is in the blue regime, being shorter than those used in most current SPRi biosensors. − As the minimum resolvable length is proportional to the detecting wavelength, the nitride-based SPRi system can deliver the images with superior resolutions. Figure b shows the microarray of 9 × 8 spots prepared on a 0.8 × 0.8 cm 2 wafer.…”

“…Surface plasmon resonance imaging (SPRi) is one of the most promising high-throughput biosensing techniques. Compared with their fluorescent counterparts, SPRi biosensors not only render the label-free process, but further expedite the assay by simultaneously visualizing numerous biomolecular interactions with a multiarray format. − Most of the current SPRi instruments are realized through the Kretschmann arrangement, wherein a prism coupler is adopted to increase the momenta of incident photons, so that SP polaritons can be launched along the metal/dielectric interface. , To record the resonance signals (intensity or wavelength), precise optical tracking components have to be implemented, − plus the indispensable refractive-index-matching oil to ensure efficient coupling between the prism and the metal-coated glass slide needs to be used . These onerous designs/procedures make on-site and personal diagnoses exceedingly difficult.…”

Recent Advances in Surface Plasmon Resonance Imaging Sensors

“…In 2008, Schasfoort and Schuck took on the challenge for SPR to be taken as a technology suitable for point-of-care (POC) diagnostics [116]. Since then, efforts have been made to build more portable, affordable and accessible SPR sensor products for POC applications.…”