Taking into consideration both the number of positive charges provided by dendrons and their associated cytotoxicity, we initiated our study from PAMAM generations G0-G2. Azidefunctionalized PAMAM dendrons G0-G2 7, 11, 13 were synthesized according to previously reported synthetic routes via repetition of Michael addition and amidation starting from 7. To convert the surface amino groups of the PAMAM dendrons to guanidinium groups, 1H-pyrazole-1-carboxamidine hydrochloride was applied as guanidinylation reagent. It was reported that different alkyl spacers with guanidine functionalization can lead to different subcellular localizations. Thus, terminal amine 9 and guanidine 10 with a longer alkyl chain containing six carbons were synthesized from 1,6-dibromohexane. 9 was synthesized according to a previously reported procedure. Afterwards, guanidinylation of the terminal amine group was conducted to obtain 10. In total, eight potential transporter modifications of various size and functionalized with different terminal groups were synthesized (Scheme 1C).