Chemical name: Methoxy polyethylene glycol chlorine
English name: mPEG-Chloride or mPEG-Cl
Molecular formula: CH₃O-(CH₂CH₂O)ₙ-CH₂CH₂-Cl
Molecular weight range: 350 Da to 40,000 Da (commonly 1K, 2K, 5K, 10K, 20K)
Properties: White or off-white solid (low molecular weight may be liquid)
Solubility: Readily soluble in water, DMSO, DMF, THF and other polar solvents
The structure of mPEG-Cl consists of a PEG chain terminated by methoxy groups and a chloromethyl group (-CH₂Cl) at the end. Its reaction characteristics include:
Nucleophilic substitution reaction (SN₂ reaction) :
It can react with primary amines (-NH₂) to form stable secondary amine bonds (-NH-CH₂-PEG).
It can also react with thiol groups (-SH) or hydroxyl groups (-OH) under alkaline conditions, but the efficiency is relatively low.
Reaction conditions:
It is usually carried out in a buffer solution with a pH of 8 to 10, such as carbonate buffer solution.
Organic bases such as triethylamine (TEA) or DIEA can be added to promote the reaction.
Selectivity: Compared with NHS-PEG or MAL-PEG, mPEG-Cl has lower reactivity, but it can be used for stable coupling under specific conditions.
3. Main Applications
(1) Biocoupling and protein modification
Amino modification: It reacts with the ε -amino group of lysine (Lys) of proteins, antibodies or peptides to achieve PEG.
Reduce immunogenicity: Prolong the half-life of drugs and improve stability (such as PEG interferon, antibody drugs).
(2) Drug delivery system
Nanoparticle surface modification: such as PEG of liposomes and polymer micelles, enhancing blood circulation time.
Small molecule drug coupling: By linking chloride groups to amino-containing drugs, solubility and pharmacokinetics are improved.
(3) Materials Science
Polymer functionalization: Used in PEG-modified hydrogels, coating materials, etc., to enhance biocompatibility.
Surface chemistry: Modified gold nanoparticles, silica gel, etc., to reduce non-specific adsorption.
