Various types of biomolecules are used in diagnosis assays: protein, antibodies, enzymes, oligonucleotides,… In certain cases, batch-to-batch discrepancies of these biomolecules affect the performance and the results of the assay. Therefore, a quick tool that requires a very small amount of material, (nearly) no preparation of the samples and that could predict good and bad batches, would be most helpful. We have recently demonstrated that FTIR spectroscopy may fulfill these requirements. FTIR spectroscopy provides a precise fingerprint of the chemical composition of the sample and also reports changes in molecular conformations.

In the example below, we have analysed 10 batches of a protein product used as blocking agent in ELISA kit. These batches present variations in their efficiency in the assay but could not be discriminated using common analytical methods such as electrophoresis, size exclusion chromatography, fatty acid content,… . FTIR spectra were recorded for each batch and spectra submitted to principal component analysis (PCA). Huge differences were observed for batches presenting reduced performance in the diagnosis assays. Batches were provided by three suppliers.

Figure BSA batches+legend2

In addition, recognition models can be calibrated to predict the performance of the future batches. We have performed similar studies on oligonucleotides used as primers in other types of diagnosis assays.