Synthetic scheme for the preparation of a DNA-linked cluster of G5-FITC and G5-FA dendrimers. (1) triethylamine, MeOH, 16h; (2) DMSO; (3) EDC in DMF:DMSO (3:1; v/v); (4) 0.1M EDC/0.1 M Imidazole (pH 6.0) in 0.5 M LiCl; (5) 10 mM phosphate buffer (pH 7.4), 150 mM NaCl, annealed at 90°C for 10 min, then cooled to room temperature over 3 h.