Stoichiometry-Dependent Structural Defects in Low-Generation PAMAM Dendrimers

RP-HPLC-UV was used as an orthogonal semi-quantitative chromatographic fingerprinting technique to compare sample heterogeneity under identical analytical conditions. SEC provided apparent hydrodynamic-size information, and SEC-derived molecular-weight-related descriptors were interpreted cautiously due to the compact architecture of dendrimers and calibration with linear polymer standards, while ¹H NMR gave semi-quantitative information on branched and bridged amide environments.

The fraction of non-bridged species (<i>f</i>₀) showed a trend consistent with theoretical expectations, although the limited number of stoichiometric conditions precludes rigorous statistical validation. These findings highlight the critical role of stoichiometric control in minimizing defects and reducing structural heterogeneity in low-generation PAMAM products, and emphasize the value of complementary analytical techniques for semi-quantitative assessment of dendrimer heterogeneity.