Issue Date: August 11, 2008
Multiplexed Magnetic Nanoparticle Assay
Antibody-functionalized magnetic nanoparticles coupled with matrix-assisted laser desorption ionization (MALDI) mass spectrometry have allowed chemists in Taiwan to assay multiple human serum antigens and unravel their variant glycosylated structures in one fell swoop (Anal. Chem., DOI: 10.1021/ac800354u). The multiplexed method relies on iron oxide nanoparticles modified with antibodies to magnetically isolate antigens for MS analysis. The technique trumps the traditional single-analyte ELISA immunoassay method by rapid quantitative screening of the antigens and, knowing their respective sequences beforehand, pinpointing the structures with accurate mass information. By contrast, ELISA, the most commonly used immunoassay method for antigen-antibody detection in disease diagnosis, achieves about the same accuracy in identifying target biomarkers but leaves molecular structures unclear. The hardest part of the study, according to Yu-Ju Chen of Taiwan’s Academia Sinica, one of the study’s lead authors, was to obtain stable MALDI MS readouts. To that end, the researchers applied a seed-layer method that uses a fast-evaporating solution to promote homogeneous nanoparticle deposition on the MALDI sample plate. The research team is currently using the technique to explore inhibitor screening and protein drug analysis.
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