Biotin-dPEG®₃-NH₃+TFA-

Biotin-dPEG®3-NH3+TFA– (Biotin-dPEG®3-ammonium trifluoroacetate), product number QBD-10193, is one of several biotinylation (biotin-labeling) products offered by Vector Laboratories, Inc. The product reacts with activated esters (N-hydroxysuccinimide, 2,3,5,6-tetrafluorophenyl) of carboxylic acids under mildly basic conditions. It can be coupled directly to a carboxylic acid using 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) chemistry. Also, the product can react with carbonyl groups (aldehydes or ketones) to form a Schiff base that can be reduced to a secondary amine using sodium cyanoborohydride if additional conjugate stability is necessary.

Amphiphilic biotin-dPEG®3-NH3+TFA– dissolves equally well in aqueous buffers and organic solvents. Unlike traditional, hydrophobic biotin-labeling products, this product does not need to be dissolved in an organic solvent before being used in an aqueous reaction medium. Furthermore, biotinylation of biomacromolecules with QBD-10193 will not cause aggregation and precipitation. Eliminating aggregation should consequently improve signal-to-noise ratios in applications developed with this product. Reaction with a carboxylic acid or active ester of a carboxylic acid will yield a stable amide bond. Aldehydes are uncommon in biomacromolecules but form by oxidizing reducing sugars in glycosylated proteins. Reactions with aldehydes produce imines that can be reduced under mild conditions to secondary amines with sodium cyanoborohydride.

Any application that can utilize the powerful biotin-avidin/streptavidin affinity can use Biotin-dPEG®3-NH3+TFA–. The terminal amine of QBD-10193 offers the opportunity to biotinylate (1) the carbohydrate coat of glycoproteins and (2) surfaces consisting of carboxylic acids or their active esters. Thus, Biotin-dPEG®3-NH3+TFA– expands the range of molecules and nanoparticles for which dPEG®-biotin is useful.