MALDI-TOF MS analysis of a library of polymerizable cyclodextrin derivatives

Polymerizable cyclodextrin derivatives (PCDs) have been proposed as candida tes for use in dental therapeutics (Bowen, 1996; Bowen and Reed, 1997). Her e, PCD "libraries" were synthesized by quasi-random reactions of 6 moles of methacrylic anhydride plus 6 moles of cyclic glutaric anhydride per mole o f beta-cyclodextrin (BCD) in solution. BCD has 21 reactive sites on each of its molecules. These proportions were based on probability calculations, w hich predicted that the products should have a minimum of 2 polymerizable s ubstituents and acidic ligand groups on practically every one of the divers e product molecules. Matrix-assisted laser desorption/ionization (MALDI) ti me of flight (TOF) mass spectrometry (MS) gave valuable information regardi ng the masses of molecular ions representing the molecules that made up the PCD libraries. For the MALDI-TOF MS analyses, small samples were analyzed by the successive application of 3 solutions to the sample holder: the matr ix in acetone, the products in water, and sodium trifluoroacetate in water. The resulting spectra had > 40 envelopes of mass peaks above background. T he ionic-abundance peak heights had quasi-Gaussian configurations, with cen tral peaks having masses in the neighborhood of 2000 g/mol (Daltons). Regar dless of structural permutations within each peak, the range of these peaks was between about 1500 g/mol and 2900 g/mol. This range of masses was in a ccord with, but perhaps somewhat more narrow than, that predicted by the st atistical method, which was based on equal reactivity of all hydroxyl group s. Analysis by MALDI-TOF MS gave valuable data regarding the masses, struct ures, and characteristics of the products formed and provided unanticipated information to facilitate improvements in future PCD syntheses.