A general method for producing bioaffinity MALDI probes

A bioaffinity probe based on the idea of immobilizing avidin on the probe s urface to extract biotinylated oligosaccharide is described. The probe is p roduced by taking advantage of the natural affinity of proteins for hydroph obic polymer films. The avidin is immobilized by simply drying the solution on a polymer film surface. This produces a bioaffinity probe that shows en hanced activity for biotin-labeled oligosaccharides. The probe is produced in a matter of minutes but is highly effective for concentrating biotinylat ed oligosaccharide on the surface. The best matrix for the analysis is DHB, and the best him for the probe is a polyester material commonly used for t ransparency film. The efficacy of the probe is illustrated with neutral and anionic oligosaccharides. Oligosaccharides derivatized with biotin are ret ained while those that are unlabeled are washed away. No trace of the unlab eled oligosaccharide is observed in the mass spectrum.