glycol) - PEG or poly(ethylene oxide) - PEO, has unique
characteristics toward pharmaceutical and biomedical
applications: water solubility, lack of toxicity,
non-immunogenicity, ready clearance, non-specific
interactions with biological chemicals, and high
flexibility and mobility. It has been successfully
demonstrated in clinical uses.
chemical attachment of PEG or PEO to biologically
or pharmaceutically active small molecule drug,
macromolecules or particulates can impart significant
pharmacological advantages over the unmodified agents,
which includes increased water solubility, extended
blood circulation lifetime, reduced immunogenicity and
antigenicity, etc. Bifunctional PEG is an attractive
linker to cross-link two or more agents and substrates.
PEG Acid and NHS structure, reactivity, and stability comparision
Definitions related to PEG reagents and derivatives:
PEG: Poly(ethylene glycol) refers to an oligomer or polymer of ethylene oxide. PEG is sometimes called PEO, poly(ethyleneoxide). Commonly, PEG is a linear polymer.
PEGylation: PEGylation is a chemical process to covalently attach PEG polymers to a substrate including molecules, macromolecules, particles, surfaces etc.
Monodispersed PEG: Monodispersed PEG refers to PEG with a precise, discrete molecular weight (i.e. its molecular weight is not a range). It is a pure compound with an exact molecular formula.
Polydispersed PEG: Polydispersed PEG refers to PEG with its molecular weight distributed in a range. Often polydispersity index (PDI) is used to determine how narrow the molecular weight distribution is.
mPEG derivatives: mPEG refers to methoxylpolyethylene glycol or polyethylene glycol monomethyl ether. mPEG derivatives refer to monofunctional linear PEG derivative, mPEG-X, with an inert methoxyl cap at one end and one functional group at the other end of the PEG polymer chain. The methoxyl cap is not a functional group.
Bifunctional PEG: Bifunctional PEG derivatives have two functional groups one at each end. The two functional groups could be the same or different.
Homobifunctional PEG: X-PEG-X PEG derivatives with the same functional group at both terminals of the linear PEG chain.
Heterobifunctional PEG: X-PEG-Y PEG derivatives with two different functional groups one at each terminal.
Multi-arm PEG: Multi-arm PEG refers to PEG with more than two branches. Common multi-arm PEG includes 3-arm, 4-arm, 6-arm and 8-arm PEG.
Homofunctional multi-arm PEG: Homofunctional multi-arm PEG derivatives have the same functional group at all terminals of all branches.
Heterofunctional multi-arm PEG: Heterofunctional multi-arm PEG derivatives have different functional groups at the terminals of all branches.