Biotin-dPEG®₇-NH₂

Biotin-dPEG®7-NH2 (Biotin-dPEG®7-amine), product number 10826, is one of several biotinylation products offered by Quanta BioDesign, Ltd. The product reacts with activated esters (N-hydroxysuccinimide, 2,3,5,6-tetrafluorophenol) 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. Additionally, the product can react with carbonyl groups (aldehydes or ketones) to form a Schiff base. The Schiff base can be reduced to a secondary amine using sodium cyanoborohydride if additional conjugate stability is necessary.

Biotinylation
Biotinylation is the process of covalently attaching biotin to a molecule such as a peptide, protein, or nucleic acid, or a surface such as glass or gold. Biotinylation is used in bioconjugation research, product development, and a broad range of clinical applications.

Biotin usually is poorly soluble in water, but the amphiphilic dPEG® linker imparts excellent solubility in water and aqueous buffer and organic solvents. In the past, there have not been many choices for carbonyl- and carboxylic acid-reactive biotinylation reactions. The most popular choices were biotin-hydrazide, biocytin-hydrazide (biotin-lysine hydrazide), and biotin-LC-hydrazide (biotin-aminocaproic acid hydrazide), but all of these choices are unfortunately quite hydrophobic. Insoluble, or at least poorly soluble, in water these older, hydrophobic reagents are dissolved in organic solvents such as N,N'-dimethylformamide (DMF) or dimethylsulfoxide (DMSO) before using in an aqueous buffer. When conjugated to proteins or other biomacromolecules, the hydrophobic interactions caused or exacerbated by these reagents triggered aggregation and precipitation of conjugated molecules and increased background noise through non-specific binding.

Amphiphilic biotin-dPEG®7-NH2 dissolves equally well in both aqueous buffer and organic solvent. It is not necessary to dissolve this product in organic solvents before using it in aqueous reaction media. Furthermore, biotinylation of biomacromolecules with Biotin-dPEG®7-amine will not cause aggregation and precipitation. Eliminating aggregation consequently improves the signal-to-noise ratio of 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 not commonly found in biomacromolecules but can be formed by oxidizing reducing sugars in glycosylated proteins. Reactions with aldehydes will produce imines that can be reduced under mild conditions to secondary amines with sodium cyanoborohydride.

This product is useful in any application that requires or benefits from the biotin-avidin/streptavidin affinity. The terminal amine of Biotin-dPEG®7-amine offers the opportunity to biotinylate (1) the carbohydrate coat of glycoproteins by oxidizing reducing sugars to aldehydes, and (2) consisting of carboxylic acids or their active esters. Thus, Biotin-dPEG®7-amine expands the useful range of molecules and nanoparticles for dPEG®-biotin applications.

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