Further Variations of the MALDI Theme

The properties of a surface may to a certain extent be tailored to optimize its performance for a particular field of application. Basically, the matrix-analyte pair is replaced by a customized surface-analyte pair that is subjected to laser irradiation. While this approach, on the one hand, simplifies sanple preparation, on the other it necessitates preparation of a set of delicate surfaces to be used for different needs. 

Silica gel can be derivatized in multiple ways, e.g., by covalently binding ligands via Si-O bonds to its surface. Both surface-enhanced laser desorption/ionization (SELDI) and material-enhanced laser desorption/ionization (MELDI) make use of the presence of metal complexes on a silica gel surface to selectively adsorb target compounds via conplex formation ftom solution to a target surface [197]. Besides silica gel, also cellulose or glyddyl methacrylate particles, and even diamond powder have been enployed as carriers for the metal conplex-fiinctionalized groups [198,199]. 

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