Probing the molecular weight of poly(amidoamine) dendrimers and derivatives using SDS-PAGE

Abstract

As a simple and versatile technique, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to analyze the molecular weight (M_w) of poly(amidoamine) (PAMAM) dendrimers and their derivatives. By optimizing the gel concentration and electrophoretic voltage, we were able to probe the M_w of PAMAM dendrimers of different generations terminated with amine, acetyl, hydroxyl, and carboxyl groups. We show that for acetyl-, hydroxyl-, and carboxyl-terminated dendrimers with neutral, slightly positive, and negative surface charges, the protein standards can be directly used for the determination of their M_ws. However, for amine-terminated PAMAM dendrimers, one has to subtract the contribution of SDS molecules adsorbed onto the dendrimer surfaces. Our results clearly indicate that besides the utilization of other techniques, SDS-PAGE could be used as an alternative inexpensive, rapid, and reliable method to determine the M_w of PAMAM dendrimers with different surface functionalities.