dPEG®₁₂-biotin acid

Product number 10197, dPEG®12 biotin acid, is a biotinylation reagent containing a single molecular weight polyethylene glycol (PEG) spacer. This product is a free acid rather than an active ester. The terminal propionic acid group couples to amines directly using a carbodiimide such as EDC. Also, the terminal carboxylic acid can be functionalized as an N-hydroxysuccinimidyl (NHS) or 2,3,5,6-tetrafluorophenyl (TFP) ester for reaction with amines.

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 finds extensive use in bioconjugation research and product development. Biotin usually is poorly soluble in water, but the amphiphilic dPEG® linker imparts excellent solubility in water or aqueous buffer and organic solvent. In the past, many experiments have coupled aminocaproic acid to biotin to use as a spacer between biotin and the surface to be modified. Unfortunately, aminocaproic acid (often abbreviated as LC, for "long chain") is highly hydrophobic. Insoluble in water, LC-biotin must be dissolved in an organic solvent such as DMF or DMSO before using it in an aqueous buffer. When conjugated to proteins or other biomacromolecules, LC-biotin can trigger aggregation and precipitation of conjugated molecules due to hydrophobic interactions. In assays, the hydrophobicity of LC-biotin also increases background noise through non-specific binding.

Amphiphilic dPEG®12 biotin acid can be dissolved both in water or aqueous buffer and in organic solvents. It does not cause aggregation or precipitation of biomolecules. Using 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) chemistry, PN10197 can be coupled directly to free primary amines in aqueous media. These free amines can be on a protein, peptide, or the treated surface of a nanoparticle. Moreover, the functionalization of the carboxylic acid with other reactive groups permits coupling directly to surfaces such as glass, gold, or magnetic nanoparticles. The linker length of dPEG®12 biotin acid (50.7 – 51.7 Å) is longer than the linker length of LC-biotin and longer than the linker length of LC-LC-biotin. The performance characteristics of dPEG®12-biotin acid are quite superior to both LC-biotin and LC-LC-biotin.

Product number 10197 is the precursor product of our popular products PN10198, NHS-dPEG®12-biotin, and PN10008, Biotin-dPEG®12-TFP ester. Many applications use this product to take advantage of the strong avidin-biotin binding interaction. Such applications include single-cell imaging of protein secretion, developing biosensors, isolating specific cell types by separation with magnetic beads, characterizing and understanding the streptavidin-biotin interaction, creating affinity-based probes, and assembling supramolecular nanostructures.

Application References:

Hermanson, G. T. Chapter 11, (Strept)avidin-Biotin Systems. Bioconjugate Techniques, 3rd edition. Academic Press: New York, 2013, 465-505.
Hermanson, G. T. Chapter 18, PEGylation and Synthetic Polymer Modification. Bioconjugate Techniques, 3rd edition. Academic Press: New York, 2013, 787-838.

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