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Lipoamido-dPEG®₁₂-TFP ester (QBD-10814)



Lipoamido-dPEG®12-TFP ester, product number QBD-10814, is a single molecular weight, discrete PEG (dPEG®) modification reagent. The product consists of alpha-lipoic acid and a 2,3,5,6-tetrafluorophenyl (TFP) ester on opposite ends of a medium-length (48 atoms) dPEG® spacer. The lipoic acid group forms two (2) coordinate covalent bonds (dative bonds) with metal, especially gold and silver. The TFP ester reacts with free amines to form amide bonds. Applications for this product include peptide or protein immobilization on metal surfaces, the formation of self-assembled monolayers (SAMs) on metal surfaces, and sensor development.

Lipoic acid, also known as α-lipoic acid and thioctic acid, is a naturally occurring antioxidant that functions as a cofactor in several enzyme systems. It consists of a dithiolane ring (a five-membered ring containing a disulfide) attached to a pentanoic acid group. As a bidentate thiol ligand, lipoic acid forms two stable dative bonds per lipoic acid group with gold, silver, and other metals. These dative bonds form with oxidized lipoic acid or reduced dihydrolipoic acid (DHLA). Because it forms two dative bonds on metal surfaces, lipoic acid is more stable than PEGylation reagents containing a single thiol. This increased stability prevents lipoic-acid-functionalized dPEG® products from being oxidized off the metal surface.

When using this product, it is typical to begin with the conjugation of the carboxyl end of the dPEG® to an amino group to form an amide bond. TFP esters optimally react with amines at pH 7.5 – 8.0. As documented in the scientific literature, TFP esters react more readily with amines and possess better hydrolytic stability than N-hydroxysuccinimidyl (NHS) esters.

After reacting the TFP ester end of the molecule, the lipoic acid end of the dPEG® linker can be reacted with metals such as gold or silver. The lipoic acid group forms dative bonds with metals with or without reduction to DHLA. If reduction to DHLA is preferred, Tris(2-carboxyethyl)phosphine (TCEP) will reduce lipoic acid to DHLA rapidly.

Lipoamido-dPEG®12-TFP ester dissolves in water or aqueous buffer and organic solvents. Stock solutions in water or aqueous buffer do not have long-term stability and should be used immediately. For stock solutions with long-term stability, we recommend dry (over 3 Å molecular sieves) water-miscible solvents such as N,N-dimethylacetamide (DMAC) or acetonitrile. Unused stock solutions in dry organic solvents should be stored at -20°C or colder.


Unit Size100mg, 1000mg
Molecular Weight954.09
Chemical formulaC₄₁H₆₇F₄NO₁₅S₂
Purity> 98%
SpacersdPEG® Spacer is atoms 48 and 52.0 Å
Typical solubility properties (for additional information contact Customer Support)Methylene chloride, DMAC, DMSO or Acetonitrile.
Storage and handling-20°C; Always let come to room temperature before opening; be careful to limit exposure to moisture and restore under an inert atmosphere; stock solutions can be prepared with dry solvent and kept for several days (freeze when not in use). dPEG® pegylation compounds are generally hygroscopic and should be treated as such. This will be less noticeable with liquids, but the solids will become tacky and difficult to manipulate, if care is not taken to minimize air exposure.


Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Applicable patents and legal notices are available at legal notices.

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