Evaluation of Poly(amidoamine) Dendrimer Surface Modification with Poly(ethylene glycol) on Cytotoxicity Reduction

Generation 5 poly (amidoamine) dendrimers are promising multipotent gene delivery vectors that provide favorable DNA condensation properties; however, their high toxicity limits their applications. Toxicity of PAMAM dendrimers depends on their type, generation and applied dosage in a way that lower generations (lower than G5 dendrimers) and anionic dendrimers have lower toxicity than higher generations and cationic dendrimers. The aim of this study is to evaluate the effect of PEGylation on toxicity of G5 PAMAM dendrimers. In this study, to improve their characteristics as gene delivery carriers, G5 PAMAM dendrimers were conjugated to polyethylene glycol molecules (PEG, molecular weight 3500) at three different molar ratios of 10, 20 and 30. Also the number of conjugated PEG chains was quantified using TNBSA and Ellman assays. The effect of different degrees of PEGylation on cytotoxicity and transfection efficiency of modified PAMAM dendrimers toward BT-474 and MCF-10A cell lines were assessed. Compared to unconjugated, PEG conjugated PAMAM dendrimers had lower in vitro cytotoxicity, particularly at higher PEG to PAMAM molar ratios. Among all prepared PEG-PAMAM dendrimers, G5 PAMAM dendrimers that conjugated to PEG at a molar ratio of 10/1 had the highest in vitro transfection rate in both cell lines. Our results showed that these PEG-conjugated PAMAM dendrimers possess a great potential for in vitro gene delivery.