6-Arm PEG

What is 6-Arm PEG?

6-Arm PEG derivatives are compounds that are functionalized or modified based on the molecular structure of 6-Arm PEG. Compounds with labeling functions can be prepared by introducing fluorescent dyes, radioisotopes, or other markers into the branching chain of 6-Arm PEG. Depending on the requirements of specific applications, different functionalization modifications can be made to 6-Arm PEG as needed to obtain specific chemical, physical, and biological properties. 6-Arm PEG can be applied to drug delivery, biomaterials, tissue engineering, bioanalysis, and biodiagnostics. In addition, 6-Arm PEG plays an important role in many other fields, such as nanotechnology, cell engineering, drug screening and gene delivery.

Fig. 1. Synthesis of 6-arm-PEG-catechol from 6-arm-PEG-amine (Biomaterials. 2011, 32(31): 7961-7970).

Advantages to 6-Arm PEG

Multi-branched Structure

Compared to linear PEG derivatives, 6-Arm PEG has six branched chains. The multi-branched structure provides more sites for functionalization and cross-linking, which can increase the stability of the material, drug loading capacity, and cell attachment sites, thus improving its performance.

Highly Tunable

The multi-branched structure of 6-Arm PEG and the length of the branching chain can be adjusted on demand. This tunability makes 6-Arm PEG a material with highly customizable capabilities.

Increased Drug Loading Capacity

The drug loading capacity of 6-Arm PEG is higher because more drug molecules can be suffixed or encapsulated onto the PEG-glycol structure. As a result, 6-Arm PEG can potentially carry greater therapeutic agent payloads.

Preparation of 6-Arm PEG

Preparation of 6-Arm PEG involves activation of the PEG monomer, which is then reacted with a polyether alcohol monomer or prepolymer to form a branched structure. Subsequently, the product is purified by solvent extraction, gel permeation and crystallization to remove excess monomers, by-products and solvents. Finally, the structure of 6-Arm was characterized and verified by various analytical techniques such as NMR, mass spectrometry, etc.

Cross-linking Mechanism of 6-Arm PEG

6-Arm PEG is cross-linked by different cross-linking mechanisms. The following are the cross-linking mechanisms of 6-Arm PEG:

(1) Esterification reaction. In 6-Arm PEG, the hydroxyl groups (-OH) undergo esterification reactions with anhydrides and acids (e.g., dianhydrides and dicarboxylic acids), resulting in crosslinking. Hydrogels and materials made of polymer can exhibit this mechanism.

(2) Amidation reaction. Amidonation is the formation of a cross-linked structure when an amine group forms amide bonds with an anhydride or an acid.

(3) Nucleophilic reactions. A number of nucleophilic reactions can be used to build stable hydrogels, coatings, and nanoparticles, including sulfite esterifications, imidations, and imine aminations.

Cross-linking Properties of 6-Arm PEG

• Mechanical properties: Upon crosslinking, 6-Arm PEG creates a three-dimensional network structure, which enhances the mechanical properties of the material. Hence, 6-Arm PEG is used to fabricate scaffolds, hydrogels, and artificial tissues.
• Swelling: By cross-linking the material, swelling is reduced, and stability and durability are improved.
• Material stability: PEG with 6 arms is crosslinked and resistant to temperatures, solvents, enzymes. It can be used in biosensors, coatings, etc.

BOC Sciences offers GMP-grade PEG derivatives and bulk orders through custom synthesis, giving us the opportunity to meet our customers' specific quality requirements. We are happy to answer any questions you may have about our products.

Reference

1. Jeong, J.H. et al. Surface camouflage of pancreatic islets using 6-arm-PEG-catechol in combined therapy with tacrolimus and anti-CD154 monoclonal antibody for xenotransplantation. Biomaterials. 2011, 32(31): 7961-7970.