Polyethylene glycol (PEG) compounds contain a polyether unit, commonly expressed as R
1-(O-CH
2-CH
2)
n-O-R
2. They are generally biocompatible, non-toxic and stable in both organic and aqueous solutions, and so are extensively used in biological applications, as well as nanotechnology and materials research. Proteins with PEG chain modifications and compounds encapsulated in PEG liposomes exhibit a longer half-life
in vivo than their non-PEGylated counterparts, a phenomenon known as PEG shielding. Functionalised PEG lipids and phospholipids can be used for protein-PEG conjugation.
4-Arm PEG-Azide is a multiarm PEG derivative with azido (N3) groups at each terminal of the four arms connected to one pentaerythritol core. PEG azide can be used for PEGylation via a click chemistry reaction with alkyne or acetylene.