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

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(w)s. 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.