What is the difference between PEG and PEO?



Polyethylene glycol (PEG), also known as polyethylene oxide (PEO), is an amphiphilic polyether that is soluble in water and most organic solvents. Typically, materials with molecular weights less than 20,000 g/mol are called PEGs, while materials with molecular weights greater than 20,000 g/mol are called PEOs. These polymers are soluble in water and organic solvents such as ethanol, acetonitrile, toluene, acetone, dichloromethane, hexane and chloroform. PEG and its derivatives are one of the few polymers available for use in biopharmaceutical products certified by the US FDA.

PEG modification refers to the covalent attachment of PEG polymer chains to target molecules, usually small molecule chemical drugs or large biomolecules such as peptides, proteins, carbohydrates, lipids, oligonucleotides, affinity ligands, cofactors, Liposomes and other biological materials.

However, the application of polypeptide molecules as drug lead compounds in vivo is limited to a certain extent, mainly reflected in the filtration of the glomerulus of organisms, the hydrolysis and destruction of proteases in vivo, and the antigenic reaction caused by polypeptide molecules in vivo. After the polypeptide is modified with PEG (Pegylation), the limitations of the above three aspects are greatly reduced, thereby improving the application of the polypeptide in vivo.

The main modification sites are the N-terminus, C-terminus of the polypeptide, Lys side chain and Cys sulfhydryl group. The molecular weight range of PEG single molecule used for modification is between PEG2~PEG24; the molecular weight range of PEG macromolecule is between PEG500~PEG40K. Or modify various PEG raw materials on the market to the peptide.

The conjugation or non-covalent attachment of PEG molecules to other molecules or nanoparticles and microparticles is known as PEGylation. In drug delivery, PEGylation can provide “stealth” properties and biocompatibility for biopharmaceuticals (eg, peptides, proteins, oligonucleotides) and particle delivery systems, and optimize the pharmacokinetic properties of drugs. PEG hydrogels can be prepared by cross-linking bifunctional PEGs and are commonly used for controlled drug release and scaffolds in tissue engineering.