Figure 5.

SE-HPLC and gel electrophoresis of green emitting CdSe/ZnS nanocrystals coated with three peptides of different charge. (a) Theoretical net charge of peptides 5, 4, and 6 in TBE buffer pH 8.3. The charges were calculated from the pK values of the amino acids’ functional groups in each sequence⁶¹ as a function of cysteine contribution to the charge and assuming a charge of about +0.5 for the non-acetylated N-terminal amine of peptide 4 (pK between 8.0 and 9.0) and −1.0 for the succinylation of peptide 6 (pK between 3.0 and 5.0). (b) Nanocrystals coated with peptides 5 (dash), 4 (dot), or 6 (solid) have similar retention times on an SE-HPLC column. (c) The same nanocrystals migrate at different positions on a 0.5% agarose gel, in good agreement with the theoretical charge of each peptide. (right facing solid triangle): loading wells. −: anode.