A carboxylate-terminated PAMAM dendrimer; ~48.3 Å in diameter in water and has 24 surface groups; binds to cytochrome c and decreases its hydrolysis by chymotrypsin by ~30% in a cell-free assay at 1 µM; when coupled to PEI, PAMAM G2.5 co-assembles with DNA into DNPs, which increase transfection efficiency and decrease DNA nuclease degradation in HeLa cells; when coupled to ADAC, PAMAM G2.5-ADAC inhibits forskolin-induced activation of adenylyl cyclase in CHO cells expressing the human adenosine A3 receptor (EC50 = 1.6 nM)