A carboxylate-terminated PAMAM dendrimer; has been used in a drug delivery system; ~87.9 in diameter in water and has 96 surface groups; Unlike PAMAM G5.0, it does not rupture bilayer lipid membranes at 50 µM; PAMAM G4.5 carboxylate disulfur-linked aggregates encapsulating ferulic acid and paclitaxel induce apoptosis and decrease the mitochondrial membrane potential in multidrug-resistant KB-8-5 cancer cells at 10 UG/ml; complexes of PAMAM G4.5 carboxylate with the active component of cisplatin are cytotoxic to A2780 cancer cells (IC50 = 620 nM); a fluorescently labeled form of PAMAM G4.5 carboxylate selectively accumulates in tumors and kidneys over liver, spleen, heart, and lungs in a 4T1 murine mammary carcinoma model