New Ionic bis-MPA and PAMAM Dendrimers: A Study of Their Biocompatibility and DNA-Complexation.

Herein, the synthesis of five novel ionic dendrimers and their evaluation as biological carriers is reported. The compounds include an ionic bis-MPA dendrimer and four PAMAM dendrimers of different generations decorated with negatively charged hydrophilic chains of 2-[2-(2-methoxyethoxy)ethoxy]acetic acid as counter ions in order to increase their biocompatibility. The ionic dendrimers derived from bis-MPA have a low cytotoxicity at 0.5mgmL(-1) against U251MG and are even less toxic against mesenchymal stem cells; however, the PAMAM derivatives show high cytotoxicity at the same concentration. The five compounds are able to form complexes with plasmid DNA at different N/P ratios. The cytotoxicity and complexation ability of the new dendrimers were also compared with jetPEI, a linear polyethylenimine derivative commercially available as transfection reagent. The results indicate that the cytotoxicity of the ionic PAMAM dendrimers remains as an important drawback, whereas the ionic I-bis-MPA compound exhibits a high ability to complex pDNA and very low toxicity compared with jetPEI.