To elucidate the whereabouts of the caged nucleotides, we continued our study with colocalization experiments. It was previously reported that PAMAM-NH2 localize in the mitochondria and nuclei preferentially, due to the surface positive charges. It was also reported that guanidinium-rich molecular transporters are able to traverse the nuclear membrane and accumulate in the nucleus, leading to interesting applications in drug delivery. We conducted Another potential destination of the caged nucleotides are lysosomes. Therefore, LysoTracker ® Deep Red was used for staining in colocalization experiments. The images from lysosome colocalization were analyzed and showed that 77% of (G1-NH2-) 19, 43% of (G2-NH2-) 21, and 34% of (G2-guanidine-) 22 localize to lysosomes (Figure ). Thus, a considerable number of dendronized DEAC450 caged ATPs were scavenged by lysosomes. This might be due to the acidic nature of lysosomes, where the lipophilic basic amine and guanidine moieties of dendronized DEAC450 caged ATPs are partially trapped.