Figure 2
A. Synthesis of QD conjugate of (R)-thioctic acid 3. Reagents and conditions: (a) NaBH4, EtOH, H2O; (b) CdS/ZnS QD (2a, toluene-soluble), DMSO, EtOH, 60-80°C. B. Synthesis of QD-nucleoside conjugates 4 and 5 linked through amide chains that are anchored on the QD surface through the thiol groups of thioctic acid. (a) N-Boc-ethylenediamine, DCC, DMAP, DCM; (b) TFA:DCM (1:1); (c) CGS21680 1a, DIEA, PyBOP, DMF; (d) Solid phase NaBH4 bead, DMF, EtOH, H2O; (e) CdS/ZnS (QD) (2a, toluene-soluble), DMSO, EtOH, 60-80°C. The number of adenosine moieties attached per QD was approximately 100-180 for conjugate 5 and 50-110 for conjugate 4.