Biotin-dPEG®₇-NH₂

Biotin-dPEG®7-NH2 (Biotin-dPEG®7-amine), product number QBD-10826, is a short (25 atoms, 29.8 Å), hydrophilic, water-soluble, discrete PEG biotinylation product that reacts with carboxylic acids and their activated esters [N-hydroxysuccinimidyl (NHS), 2,3,5,6-tetrafluorophenyl (TFP)] to form stable amide bonds. Additionally, Biotin-dPEG®7-NH2 forms amide bonds directly with carboxylic acids using 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) chemistry. Furthermore, the product can react with carbonyl groups (aldehydes or ketones) to form a labile Schiff base, which can be reduced to a secondary amine using sodium cyanoborohydride for additional conjugate stability.

Amphiphilic biotin-dPEG®7-NH2 dissolves equally well in both aqueous buffer and organic solvent. It is not necessary to dissolve this product in an organic solvent before using it in aqueous reaction media. Furthermore, biotinylation of biomacromolecules with QBD-10826 will not cause aggregation and precipitation. Eliminating aggregation should consequently improve the signal-to-noise ratio of applications developed with this product. Aldehydes are uncommon in biomacromolecules. However, the oxidation of reducing sugars in glycosylated proteins (for example, using sodium periodate) forms aldehydes on the carbohydrate coats of glycoproteins. Reacting Biotin-dPEG®7-amine with aldehydes will produce labile imines or Schiff bases that can be reduced under mild conditions with sodium cyanoborohydride to form more stable secondary amines.

Any application that can take advantage of the strong biotin-avidin/ streptavidin affinity can use Biotin-dPEG®7-NH2. The terminal amine of QBD-10826 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®7-NH2 expands the range of molecules and nanoparticles for which dPEG®-biotin is useful.