(a) Competitive inhibition of the cluster agent (40 nM) by free FA (5 mM). (b) The cluster failed to bind to the folate receptor down-regulated KB cells (FAR-) (c) Control groups (2: G5-FITC-cON34; 3: mixture of G5-FA-sON34 and G5-FITC-cON34 with no annealing process) showed no non-specific binding, suggesting a clustering of dendrimer-DNA conjugates did not occurin vitrowithoutin situDNA hybridization reaction. (d) Comparison of the mean fluorescence intensity of the cluster and the cluster antagonized by free FA, with controls (G5-FITC-cON34 and the mixture of the DNA-dendrimer conjugates.