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Carboxy-PEG-Thiol Compounds

A carboxylate, monodentate thiol polyethylene glycol compound for pegylating metal surfaces.

Pierce CT(PEG)12

Thermo Scientific Pierce CT(PEG)12, or carboxy-PEG12-thiol, is a carboxyl- and sulfhydryl-terminated compound that contains a 12-unit polyethylene glycol (PEG) spacer and is used to modify surfaces such as quantum dots, monolayers and magnetic particles.

CT(PEG)12 is monodentate thiol-terminated and carboxylic acid pegylation reagent. The PEG compound has a defined molecular weight and spacer length and is useful for modifying surfaces such quantum dots, self-assembled monolayers and magnetic particles. Functionalization of solid surfaces with this polyethylene glycol reagent provides carboxylate "handles" for protein immobilization via EDC crosslinking and significantly reduces nonspecific protein binding and provides.


  • Metal-binding – terminal monodentate thiol reacts spontaneously with gold surfaces through dative binding
  • Carboxylate – terminal carboxylic acid group allows conjugation to amine-containing affinity ligands using carbodiimide (EDC) and Sulfo-NHS crosslinking chemistry
  • Polyethylene glycol – PEG groups are flexible, non-immunogenic, hydrophilic, and significantly reduce nonspecific binding of surfaces for protein methods
  • Spacer arm – 12-unit PEG spacer is nearly 48 angstroms long, minimizing steric hindrance for protein immobilization and binding assays

Product Details:

Carboxy-PEG12-thiol; CT(PEG)12

Chemical structure and properties of CT(PEG)12:

  • Alternative name: Carboxy-PEG12-Thiol
  • Chemical name: 1-mercapto-3,6,9,12,15,18,21,24,27,30,33,36-dodecaoxanonatriacontan-39-oic acid
  • Chemical formula: C27H54O14S
  • Molecular weight: 634.77
  • Spacer arm: 47.8 angstroms
  • Form: colorless to pale yellow liquid
  • Solubility: dissolve in DMSO or DMF for use

The use of MT(PEG)4 with CT(PEG)12 in surface modification can form a hydrophilic “lawn” of methyl ether-terminated PEGs with periodic exposed carboxylic acid-containing PEGs. The exposed carboxylic acid groups can be coupled to affinity ligands using the carbodiimide coupling reaction with EDC and sulfo-NHS.

Metal surface pegylation with carboxy-PEG-thiol
Modification of metal surfaces with MT(PEG)4 and CT(PEG)12 pegylation reagents.

General References:

  1. Prime, K.L. and Whitesides, G.M. (1991). Self-assembled organic monolayers: model systems for studying absorption of proteins at surfaces. Science 252:1164.
  2. Bentzen, E.L., et al. (2005). Surface modification to reduce non-specific binding of quantum dots in live cell assays. Bioconjugate Chem 16:1488-94.
  3. Lin, P-C., et al. (2006). Ethylene glycol-protected magnetic nanoparticles for a multiplexed immunoassay in human plasma. Small 2(4):485-9.
  4. Zheng, M., et al. (2003). Ethylene glycol monolayer protected nanoparticles for eliminating nonspecific binding with biological molecules. J Am Chem Soc 125:7790-1.
  5. Verma, A. and Rotello, V.M. (2005). Surface recognition of biomacromolecules using nanoparticle receptors. Chem Commun 3:303-12.
  6. Kidambi, S., et al. (2004). Selective depositions on polyelectrolyte multilayers: self-assembled monolayers of m-dPEG acid as molecular template. J Am Chem Soc 126:4697-03.

Related Products:

Protein PEGylation technical guide (and PEG reagent selection guide)

Ordering Information
Product # Description Pkg. Size Instructions MSDS CofA Price
26133 CT(PEG)12
Formulation: 12-unit ethyleneglycol functionalized with carboxyl and sulfhydryl ends; solid
Sufficient For: 6mL of typical 1X (25mM) reaction solution
100mg Product Instructions for product #26133 CT(PEG)12 MSDS for product #26133 CT(PEG)12 Certificate of Analysis for product #26133 CT(PEG)12 $331.00

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Instructions | MSDS | CofA
Product Instructions | MSDS | CofA  

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