Figure 3
Synthesis of PEGylated QD conjugates 6 and 7, coupled through a PEG-linked thioctic acid moiety. Reagents and conditions: (a) DCC, DMAP, DCM; (b) PPh3, THF, H2O; (c) CGS21680 1a, DIEA, PyBOP, DMF; (d) Solid-supported BH4+ bead, DMF, EtOH, H2O; (e) CdS/ZnS QD (toluene-soluble), DMSO, EtOH, 60-80°C. The number of adenosine moieties attached per QD was approximately 100-180 for conjugate 7 and 50-110 for conjugate 6.