PAMAM dendrimer G3.5 carboxylate (PAMAM G3.5) is a polyamidoamine (PAMAM) dendrimer with carboxylate termini that has been used as a drug delivery system in vitro and in vivo.1,2 It is approximately 66.1 Å in diameter in water and has 48 surface groups.3 PAMAM G3.5 is active against E. coli (IC50 = 22 mg/ml) and increases the mitochondrial membrane potential of isolated rat liver mitochondria when used at concentrations ranging from 10 to 50 µM.4,5 Unlike amine-terminated PAMAM G4.0, PAMAM G3.5 (20 µM) is not toxic to zebrafish embryos.6 A fluorescently labeled form of PAMAM G3.5 enters Caco-2 cells via dynamin-, clathrin-, and caveolin-mediated endocytosis.7 Conjugates of PAMAM G3.5 with the active fragment of the DNA cross-linking agent oxaliplatin (Item No. 13106) are cytotoxic to A2780 ovarian, MCF-7 breast, and Caco-2 colon cancer cells and BJ fibroblasts (IC50s = 0.08, 4.1, 0.39, and 3 µM, respectively).1 PAMAM G3.5 in complex with the topoisomerase I inhibitor camptothecin (Item No. 11694) increases the oral bioavailability of camptothecin in mice.2WARNING This product is not for human or veterinary use.