Highly sensitive and multiplexed mass spectrometric immunoassay techniques and clinical applications.

Immunoassay is one of the most important clinical techniques for disease/pathological diagnosis. Mass spectrometry (MS) has been a popular and powerful readout technique for immunoassays, generating the mass spectrometric immunoassays (MSIAs) with unbeatable channels for multiplexed detection. The sensitivity of MSIAs has been greatly improved with the development of mass labels from element labels to small-molecular labels. MSIAs are also expended from the representative element MS-based methods to the laser-based organic MS and latest ambient MS, improving in both technology and methodology. Various MSIAs present high potential for clinical applications, including the biomarker screening, the immunohistochemistry, and the advanced single-cell analysis. Here, we give an overall review of the development of MSIAs in recent years, highlighting the latest improvement of mass labels and MS techniques for clinical immunoassays.