mPEG-Acide / mPEG-CM / Methoxypolyethylene glycol carboxyl

Poly (ethylene glycol), PEG, is a type of non-ionic ether polymer with low molecular weight and two end groups of hydroxyl groups. It is one of the most commonly used organic polymer materials at this stage. It is usually obtained by the reaction of ethylene oxide and water or repeated addition polymerization between glycol monomer molecules. Its chemical structure is HO(CH²CH²O) ⁿH (with the change of molecular weight, the value of n in the structure will also change accordingly). Due to the difference in polymerization degree n, polyethylene glycol has a relatively wide molecular weight distribution range (usually between 200 and 20000), and the difference between molecular weights also leads to relatively large differences in the physical properties of the corresponding compounds. With the increase of the relative molecular mass of polyethylene glycol, its density and freezing point are increased, while its hygroscopicity and solubility are decreased.

Figure 1. Structures of polymers 4cPEG and mPEG-COOH.(Li Q, et al.; 2016)

Monomethoxypolyethylene glycol (mPEG) is a widely used polyether polymer compound with high water solubility. Its repeating unit is an ethoxy group, and its two ends are capped with methoxy and hydroxyl groups. It has high polarity and can form hydrogen bonds with water. It is a hydrophilic polymer compound. Its properties change with the change of molecular weight. It is liquid when the molecular weight is 300Da, and its viscosity increases with the increase of molecular weight; when the molecular weight increases to 1000Da, it is solid, and then it becomes a white waxy solid state with the increase of molecular weight. Among them, mPEG is non-toxic when the molecular weight is above 1000Da, and it is one of the very few synthetic polymers approved by the US Food and Drug Administration (FDA) for in vivo injection. The melting point of solid mPEG is proportional to the molecular weight and gradually approaches 65℃.

Since the 1970s, Abuchowsk et al. used polyethylene glycol (PEG) to modify bovine serum albumin and found that it could effectively change its immune properties. Subsequently, researchers used PEG to modify the anticancer drug asparaginase and applied it in clinical practice. Since then, researchers have also successfully applied PEG to the modification of protein drugs such as acylglycoside deaminases, interferons, camptothecin, paclitaxel, cytarabine, scutellariae and other small molecule drugs. After that, with the development of PEG, its application range has become increasingly wider, such as additives for plastics and rubbers in the medical field, preparation of surfactants, coatings and inks, pharmaceutical industry and cosmetics. In the medical field, protein peptide drugs can be well solved by mPEG modification to solve the defects of low immunogenicity, short half-life, poor stability and low solubility; in the biological field, protein enzymes can be modified by mPEG derivatives to improve their activity. The conformation of mPEG-modified proteins generally does not change, and the biological activity of the conjugate is mainly generated by the protein part of the conjugate, and by changing the functional group of mPEG, it is bonded to the predetermined position of the protein peptide. When mPEG-modified proteins are used clinically for treatment, no anti-mPEG antibodies are found. The hydroxyl groups of mPEG can be converted into active groups such as amino, carboxyl, p-toluenesulfonate and aldehyde. The introduction of these functional groups has greatly increased its application range, making it have broad prospects in multiple applications such as peptide synthesis, polymer synthesis, organic synthesis, targeted drug administration and sustained and controlled release of drugs.

Alternate Names:
Methoxy poly(ethylene glycol) carboxylate
Methoxy PEG carboxylate
mPEG carboxylic acid
mPEG-carboxyl
Methoxy poly(ethylene glycol) acid

References:
1. Li Q, et al.; Controlling Hydrogel Mechanics via Bio-Inspired Polymer-Nanoparticle Bond Dynamics. ACS Nano. 2016, 10(1):1317-24.

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