Chelate Derivatives for Imaging Applications

NHS ester on the dye and prevent conjugation to the dendrimer. For reactions done in organic solvent, add triethylamine to a final concentration of 1.25 times greater than the amount of reactive dye to be added to the solution. 

Add a quantity of the DyLight 649 dye to the dendrimer solution to provide at least a 1.25-fold molar excess of dye over the amount of dendrimer present (for nonaqueous reactions) or a 6-15-fold molar excess for aqueous reactions. Mix well to dissolve. The optimal amount of dye added should be determined experimentally by preparing a series of conjugates using different molar ratios of dye-to-dendrimer. 

React for 1 hour at room temperature with mixing. 

Remove unreacted dye and reaction by-products from the modified dendrimer by gel filtration or dialysis, using a molecular weight cutoff suitable for the size of the dendrimer. 

The polyvalent nature of dendrimers has been investigated as vehicles for carrying multiple chelator groups to enhance signals in various imaging applications (Barthand Soloway, 1994 Yoo et al., 1999 Kobayashi et al., 2000, 2001 Sato et al., 2001). In addition, in certain chelate-dendrimer constructs, excess amines on the dendrimer surface can aid in the cellular uptake process through charge-mediated endocytosis. 

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