Biotinylation of Amine-Dendrimers

A similar type of biotin-dendritic multimer also was used to boost sensitivity in DNA microarray detection by 100-fold over that obtainable using traditional avidin-biotin reagent systems (Stears, 2000 Striebel et al., 2004). With this system, a polyvalent biotin dendrimer is able to bind many labeled avidin or streptavidin molecules, which may carry enzymes or fluorescent probes for assay detection. In addition, if the biotinylated dendrimer and the streptavidin detection agent is added at the same time, then at the site of a captured analyte, the biotin-dendrimer conjugates can form huge multi-dendrimer complexes wherein avidin or streptavidin detection reagents bridge between more than one dendrimer. Thus, the use of multivalent biotin-dendrimers can become universal enhancers of DNA hybridization assays or immunoassay procedures. 

Biotinylated dendrimers also have been used to develop targeting conjugates for therapeutic use in targeting cancer cells. Wilbur et al. (1998) studied several different PAMAM 

Dendrimer-biotin-carbonyl metallo immunoassay detection reagent 

The biotinylation of amine-dendrimers may be accomplished using either an organic reaction environment or an aqueous medium. For modification of PAMAM dendrimers with a biotinidase resistant biotin compound, Wilbur et al. (1998) performed the reaction in DMF with triethylamine as catalyst (proton acceptor). The following protocol illustrates this type of procedure using the biotinylation reagent NHS-PEG/pbiotin, which closely compares to the biotinidase insensitive compound used in the published procedure. 

In a fume hood, dissolve an amine-containing dendrimer in DMF at a concentration of at least lOmg/ml with mixing. For the modification of a G-3 dendrimer, Wilbur et al. (1998) used approximately 240mg of dendrimer dissolved in 10ml of DMF. Other concentrations will work well in this procedure. 

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