Mass Spectrometric Immunoassay Development for the Targeted Quantification of Protein Biomarkers and Their Variants

Project conducted by PhD candidate Jie Gao

Main content

Commonly used immunoassays such as enzyme-linked immunosorbent assay (ELISA) or radioimmunoassay (RIA) offer sensitive and fast quantification of common protein biomarkers. However, these techniques cannot differentiate among the diverse isoforms of protein biomarkers, which could be clinically important as the fingerprints for different pathologies and diseases. Matrix-assisted Laser Desorption/Ionization Time-of-Flight mass spectrometry (MALDI-TOF MS) is a powerful technique allowing quantification of proteins and their isoforms. In addition, the technique allows fast and simultaneous detection of multiple protein biomarkers from small sample volumes, which is paramount in epidemiological and clinical studies based on precious biobank material. Here, taking advantages of efficient affinity extraction using magnetic beads (MB) and simultaneous MALDI-TOF MS readout, we have developed a multiplex immunoassay for targeted quantification of four disease related serum markers (inflammation: C-reactive protein (CRP), serum amyloid A (SAA) and calprotectin (S100A8/A9 complex); kidney function: cystatin C). 

Our method demonstrates high performance for biomarker analysis with good linearity (R2 > 0.95), low sample consumption (20µl of human serum/plasma) and a throughtput of hundred samples per day. Moreover, our approach delivers direct and quantitative information about the protein diversity.