The majority of proteins are glycosylated: they possess oligosaccharide chains and are hence termed glycoproteins. Oligosaccharides, also called carbohydrate or sugar, are often quite large (as large as some protein domains for example) and they have many functions in molecular interactions.

Description of the advantages of combining the use of peptide chips with direct label-free detection as achieved by SPR imaging (SPRi).

This application note shows that the HORIBA Scientific SPRi platform is suitable for the analysis of aptamer-based molecular interactions. For this purpose, the interaction between human IgE protein, an antibody involved in allergic reactions, and a human IgE specific aptamer4 is presented as proof-of-concept.

Our SPRi technology (Surface Plasmon Resonance imaging), is able to measure multiplexed label-free biolo-gical interactions in a complex media such as serum.We will demonstrate the ability to monitor specific interactions between immobilized peptides and proteins issued from non purified immune sera, using a cystamine/glutaraldehyde SAM surface chemistry on the bio-chip surface. We chose to illustrate this ability by monitoring the interaction between an ovalbumin peptide fragment and an ovalbumin immunized serum.

The purpose of this proof of concept is to show that Surface Plasmon Resonance imaging (SPRi) is a suitable technique to detect allergens. Compared with other techniques, such as ELISA or Luminex, which are based on colorimetric or fluorescence detection, this technology does not require the labeling of antibodies.

HORIBA provides the pharmaceutical industry, biotech companies and academic research laboratories with high performance instrumentation based on SPRi technology (Surface Plasmon Resonance imaging). To demonstrate the power of this technology, we carried out an experiment based on an antibody-antigen interaction. Original surface chemistry combined with an electrochemical process allows the rapid coupling of biomolecules to the gold layer (polypyrrole co-polymerisation) on the top of a glass prism.