Conformational changes of small PAMAM dendrimers as a function of their charge state: A combined electrospray mass spectrometry, traveling-wave ion mobility and molecular modeling study

Mass spectrometry was used in conjunction with ion mobility experiments and molecular modeling to study any conformational changes of two PAMAM dendrimers of different structure as a function of their protonation degree. Changes of molecular conformation conjectured from peculiar charge state distribution in the electrospray mass spectra were confirmed by collision cross section values derived from ion mobilograms and supported by theoretical calculations. Shape extension was significant for triply charged molecules of both dendrimers, but the extent of this swelling phenomenon was shown to strongly depend on the PAMAM dendrimers architecture.