To a solution of DAB-dendr(NH2)32 (306 mg, 43 mol) in DMF (25 mL) was added pentafluorophenyl 3-(10-phenothiazinyl)propionate (1.32 g, 3.0 mmol). The reaction mixture was stirred at room temperature overnight. The flask was covered with aluminium foil to protect the reaction mixture against light. Next day, 1 M NaOH (2 mL) was added in order to hydrolyse any remaining pfp-ester, and stirring was continued for a couple of hours. Further addition of 1 M NaOH precipitated the crude product as a gum, which was isolated by decantation. The gum was redissolved in DMF (50 mL) and precipitated by slow addition of 1 M NaOH (50 mL). After