Determination of molecular weight, particle size, and density of high number generation PAMAM dendrimers using MALDI-TOF-MS and nES-GEMMA

In this work we present the characterization of PAMAM dendrimers from generation two (G2) up to ten (G10) with a focus on the G5-G10 dendrimers with matrix-assisted laser desorption/ionization linear mass spectrometry (MALDI-MS) and nanoelectrospray gas-phase electrophoretic mobility molecular analysis (nES-GEMMA). For the first time the molecular masses of high-mass dendrimers G8-G10 were determined by MALDI-MS and nES-GEMMA, techniques which are based on different physicochemical principles. Obtained experimental data allows the determination of the molecular mass (up to 580 kDa with a precision below +/- 0.9%), of the spherical size (from 3.3 to 14.0 nm with a precision of +/- 0.2 nm) and the calculation of their densities. Amounts in the nanogramm range were sufficient for an analysis that could be performed within several minutes. The results based on these methods for high-generation dendrimers exhibited an excellent correlation and were compared with published data using techniques based on different principles.