Biochips that sequentially capture and focus antigens for immunoaffinity MALDI-TOF MS: a new tool for biomarker verification.

A novel approach to immunoaffinity MS is described wherein antibodies are appended to a patterned gold Biochip surface. The Biochip surface is patterned with an array of concentric immunocapture zones composed of highly hydrophilic central zones surrounded by moderately hydrophilic zones that reside on a non-wetting background, with protein attachment via electrochemically cleavable linkers. After linker cleavage, matrix application forms a discrete spot suitable for MALDI-TOF-MS. Use of the Biochip to purify transthyretin from human serum allowed a distinct resolution of four disulfide conjugates and one truncated form isoforms with good mass resolution and sensitivity.