Group Protected PEG

Group protected PEG molecules have functional groups at the end of the chain protected by a protecting group. These protectors include Boc, Fmoc and small molecules. For example, the amine group in Fmoc-NH-PEG-SCM is protected by an Fmoc group. Upon reaction, the Fmoc protecting group is removed and the two reactive end groups can be reacted with different drug molecules to form a PEG linking the two drug molecules. The protected amine can be regenerated under weakly alkaline conditions. BOC Sciences provides PEG molecules linked by protecting groups that strategically protect certain functional groups, enabling selective conjugation and incorporation of customized groups to protect the properties of the PEG for specific applications.

PEG synthesis using protecting groupFig. 1. PEG synthesis using protecting group (Tetrahedron, 2022, 119: 132861).

How to Prepare Protected PEG?

Step 1 - Selection of Protective Reagents

Depending on the application, it is necessary to select suitable protective reagents that are chemically compatible with the desired reaction and are stable.

Step 2 - PEG Protecting Groupylation

Temporary protective groups are introduced by reacting the protective reagent with the target functional group in the PEG molecule. The combination of the two can be carried out by chemical reactions such as esterification, acylation, etc. The specific reaction conditions need to be optimized according to the protective reagent used as well as the moiety.

Step 3 - Reaction Monitoring and Purification

The progress of the chemical reaction and the reaction conditions can be monitored using NMR or mass spectrometry to ensure that the protective reagent has reacted with the PEG molecule. At the end of the reaction, purification techniques need to be used to remove incompletely reacted reagents, intermediate products, etc.

Step 4 - Exposure of Functional Groups

Exposure of the functional groups needs to be realized according to the chemical form of the specific group, which can generally be treated with acidic, alkaline and other conditions.

Applications of Group Protected PEG

Drug Delivery

In drug delivery, moiety-protected PEGs can be used to enhance the stability, solubility and biodistribution of therapeutic agents. By selectively removing temporary shielding groups, the exposed functional groups in the protected PEG can be affixed to drug molecules, targeting ligands, or other components, enabling the development of targeted drug delivery systems.

Surface Modification

When applied to surfaces such as biosensors, protected PEGs can enhance stability, minimize non-specific interactions, and provide controlled release properties. Selective removal of temporary shielding groups allows for precise attachment of functional groups to the surface, resulting in customized surface properties and specific interactions with biological systems.

Bioconjugation and Protein Engineering

By selectively exposing functional groups, protected PEGs can be conjugated to proteins or peptides to improve their stability, solubility and resistance to protein hydrolysis.

Advantages of Group Protected PEG

  • Expertise and experience: We have a team of highly skilled experts in the synthesis and modification of PEG-based compounds.
  • High quality and purity: Our Group Protected PEG undergoes stringent quality control measures and employs advanced analytical techniques to verify compound integrity and purity, providing customers with reliable and consistent products.
  • Wide range of applications: Whether for drug delivery, surface modification or bioconjugation, our Group Protected PEG products can be tailored to meet the specific needs of different applications.

With expertise and a commitment to quality, BOC Sciences is a trusted partner in providing researchers and industry professionals with high-quality protected PEG compounds. If you are interested in our products, please do not hesitate to contact us at any time.


  1. Eriyagama, D.N.A.M. et al. Automated stepwise PEG synthesis using a base-labile protecting group. Tetrahedron. 2022, 119: 132861.

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BOC Sciences supplies a unique variety of PEG derivatives and functional PEG polymers. Our products offer the most diverse collection of reactivity, ready-to-use functionality, and molecular weight options that you will not find anywhere else.

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