4-Arm PEG

What is 4-Arm PEG?

Polyethylene glycol (PEG) is a multifunctional polymer that has attracted significant interest in the biomedical and pharmaceutical fields due to its biocompatibility, hydrophilicity and low toxicity. One of the most promising forms of PEG is 4-Arm PEG. 4-Arm PEG is a star-shaped polymer with four arms and multiple functional groups at the ends. The functional groups can be 4-Arm PEG-Amine, 4-Arm PEG-COOH, or 4-Arm PEG-OH, depending on the method of synthesis and the desired application. The molecular weight of 4-Arm PEG can vary depending on the number of repeating units in each arm and the degree of branching. 4-Arm PEG's chemical structure gives it unique properties that make it suitable for a variety of applications including drug delivery, enzyme modification and tissue engineering. Multiple functional groups at each arm end can be used to affix to other molecules such as drugs, proteins and peptides.

Biodegradable PEG hydrogels.Fig. 1. Biodegradable PEG hydrogels.

Structural Characterization of 4-Arm PEG

The structural features of 4-Arm PEG depend on its molecular weight, degree of branching, and terminal functional groups. 4-Arm PEG's star structure provides high loading capacity for drugs or other molecules. 4-Arm PEG's hydrophilicity prevents aggregation and enhances solubility in aqueous systems. The molecular weight of 4-Arm PEG can be customized to achieve the properties required for a particular application. Higher molecular weight polymers have longer circulation times in the bloodstream, while lower molecular weight polymers have faster clearance rates. The degree of branching of 4-Arm PEG can also be controlled to optimize its performance. Higher degrees of branching result in higher payload capacity, while lower degrees of branching result in a more rigid structure.

Application of 4-Arm PEG

Drug Delivery

Arm PEG can be used as a drug carrier and can be used for drug delivery. Due to the multiple functional groups at the end of each arm can be used to link drugs or other molecules, enabling targeted drug delivery and controlled release.

Enzymatic Modification

4-Arm PEG can be used to modify enzyme activity. 4-Arm PEG's star structure allows for the modification of multiple sites of an enzyme, resulting in a more stable and active enzyme.

Cosmetic Development

4-Arm PEG is highly hydrophilic and can provide excellent moisturizing effect to cosmetic products to prevent skin dryness and roughness. Functional group-modified 4-Arm PEG can enhance its scavenging ability for free radicals, thus protecting the skin from harmful factors such as environmental pollution and UV radiation. The process of free radicals from generation to decay is the process of electron transfer, and the free radicals that damage human health are almost always related to those more active oxygen-containing substances, so the damage of free radicals to the human body is actually an oxidizing process, and in order to reduce the damage of free radicals, we must start from the antioxidant.

Advantages of 4-Arm PEG

  • Highly hydrophilic - The molecular structure of 4-Arm PEG contains a large number of ethylene glycol units, making it highly hydrophilic.
  • Adjustable molecular weight - The molecular weight of 4-Arm PEG can be adjusted by changing the number and structure of monomers, ranging from thousands to hundreds of thousands.
  • Excellent biocompatibility - 4-Arm PEG has excellent biocompatibility and will not cause immune and toxic reactions.
  • Controllable degree of cross-linking - 4-Arm PEG can form a three-dimensional network structure through chemical cross-linking, and adjust the degree of cross-linking to control the physical and chemical properties of the material.

4-Arm PEG is a promising polymer with a wide range of potential applications in biomedical and pharmaceutical fields. Its unique structural and chemical properties make it an ideal material for drug delivery, enzyme modification and tissue engineering applications. At BOC Sciences, we are committed to providing our customers with high quality 4-Arm PEG products to advance research and improve the lives of people around the world. If you are interested in our products, feel free to contact us.


  1. Matsumura, K. et al. Urokinase injection-triggered clearance enhancement of a 4-arm PEG-conjugated 64Cu-bombesin analog tetramer: a novel approach for the improvement of PET imaging contrast. International Journal of Pharmaceutics. 2018, 545(1-2): 206-214.

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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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