Related Experiment Video
Updated: Mar 23, 2026

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight MALDI-TOF Mass Spectrometry
Published on: June 10, 2018
Characterization of Polyamidoamino (PAMAM) Dendrimers Using In-Line Reversed Phase LC Electrospray Ionization Mass
John R Lloyd1, P Suresh Jayasekara2, Kenneth A Jacobson1
1Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Abstract:
Generation 3 (G3) PAMAM dendrimers are symmetrical, highly branched polymers widely reported in the scientific literature as therapeutic agents themselves or as carrier scaffolds for various therapeutic agents. A large number of analytical techniques have been applied to study PAMAM dendrimers, but one that has been missing is in-line reversed phase LC electrospray ionization mass spectrometry (RP/LC/ESI/MS). To translate PAMAM dendrimers into therapeutic agents, a better understanding of their purity, stability and structure is required, and in-line RP/LC/ESI/MS is widely applied to all three of these analytical questions. In this study, we developed a robust in-line RP/LC/ESI/MS method for assessing stability, purity and structure of the G3 PAMAM dendrimers, and we also examined the reasons why previous attempts at method development failed. Using the RP/LC/ESI/MS method we uncovered several unique aspects of the chemistry of G3 PAMAM dendrimers. They are interconverted between two isomeric forms by dialysis, and under higher concentration levels there is an inter-molecular displacement reaction resulting, which degrades PAMAM dendrimers. Purification of G3 dendrimers by RP/LC was also previously unreported; so we slightly modified the LC/MS method for isolating individual components from a complex dendrimer mixture. Thus, we have developed a robust, comprehensive method for characterizing PAMAM dendrimers and their degradation.
Related Concept Videos
Peptide Identification Using Tandem Mass Spectrometry
This technique helps gather information regarding the protein from which the peptide was obtained and to study the peptides’ amino acid sequence. Identifying peptides from a complex mixture is an important component of the growing field of...
Mass Spectrometry of Amines
Electrospray Ionization (ESI) Mass Spectrometry
ESI utilizes electrical energy to transfer ions from the liquid phase of the sample into the...
Tandem Mass Spectrometry
Mass Spectrometry: Amine Fragmentation
In amines, the number of nitrogen atoms affects the mass of the molecular ion, which is described by the nitrogen rule of mass spectrometry. This rule states that a compound containing a single...
Matrix-Assisted Laser Desorption Ionization (MALDI)

