Fig. 1.

Synthesis of aptamer-paclitaxel conjugates. Note for reagents and conditions: (i) PABOH, EEDQ, CH₂Cl₂/CH₃OH; (ii) PNP chloroformate, pyridine, THF; (iii) PTX, DMAP, CH₂Cl₂; (iv) piperidine, DMF; (v) succinic anhydride, DIPEA, THF; (vi) Sulfo-NHS, EDCI, aptamer, dd-H₂O, DMF, 0.5 M Na₂CO₃/NaHCO₃. Fmoc = 9-Fluorenylmethoxycarbonyl, PABOH = 4-Aminophenylmethanol, EEDQ = N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline, PNP = p-Nitrophenyl, DMAP = 4-Dimethylaminopyridine, Bz = Benzoyl, Ac = Acetyl, DMF = Dimethylformamide, DIPEA = N,N′-Diisopropylethylamine, THF = Tetrahydrofuran, Sulfo-NHS = N-hydroxysulfosuccinimide sodium salt, EDCI = 1-Ethyl-3-(3-dimethyllaminopropyl)carbodiimide hydrochloride, NucA = Nucleolin aptamer, CRO = Cytosine-rich oligonucleotide