The common methods for testing the validity of potential diagnostic bio-markers, ELISAs and Western blots, are both subject to problems and are not conveniently automated for high throughput.

Mark L. Stolowitz, Stratos Biosytems LLC, Seattle, WA, USA, and colleagues have demonstrated a new way of trapping an antigen by using a patterned gold Biochip surface and immunoaffinity mass spectrometry (MS). The surface consists of concentric immunocapture zones ranging from highly hydrophilic to moderately hydrophilic. 

The antigen solution is mixed with a matrix-assisted laser desorption/ionization (MALDI) matrix solution and dried down over the pattern printed on the MALDI plate. As the mixture dries, the antigen within an outer ring is concentrated on the center spot of the target where the matrix also crystallizes. This discrete spot is suitable for MALDI-TOF-MS (Matrix-Assisted-Laser-Desorption/Ionization-Time-Of-Flight-Mass-Spectrometry).

The technique was demonstrated by quantifying transthyretin in human serum.

• Biochips that sequentially capture and focus antigens for immunoaffinity MALDI-TOF MS: A new tool for biomarker verification
  H. A. Brauer, P. D. Lampe, Y. Y. Yasui, N. Hamajima, M. L. Stolowitz,
  Proteomics 2010, 10, 3922–3927.
  DOI: 10.1002/pmic.201000219