Hydroxy-PEG-Propionic acid

The HO-PEGn-CH₂CH₂COOH series, with HO-PEG6-CH₂CH₂COOH as a representative example, is a heterobifunctional PEG derivative containing both a hydroxyl group and a carboxylic acid function connected through an extended ethylene spacer. This structural configuration enables sequential conjugation strategies for biomolecules (such as proteins with small molecules) while effectively minimizing steric hindrance. Key advantages of this series include versatile orthogonal reactivity, tunable PEG chain length (n), and significantly improved solubility for hydrophobic compounds. It is important to note that the hydroxyl group requires appropriate activation to achieve efficient covalent conjugation.