Stimuli response behaviors of cystamine-core dendrimer in the presence of several reducing agents including vitamin C, sodium bisulfite, and DL-Dithiothreitol are described. A competitive redox cleavage and suprarnolecular aggregate formation model is proposed based on PFG NMR and H-1 NMR titration experiments. Furthermore, reduction-responsive release of guest molecules from interior pockets of the cystamine-core dendrimer is confirmed by NOE studies. The results suggest that cystamine-core dendrimer is a versatile scaffold or precursor in the design of reduction-sensitive polymeric nanocapsules for biomedical purposes.