Some questions about PEG products


PEG products

Q: What is Modified PEG/Modified PEG/mPEG?
A: mPEG is methoxy polyethylene glycol or polyethylene glycol monomethyl ether. mPEG derivatives refer to monofunctional substituted linear polyethylene glycol derivatives with the general formula mPEG-X, that is, one end of the polyethylene glycol polymer chain is an inert methoxy group, and the other end is a functional group X.

Q: What is PEGylation | PEGylation?
A: PEGylation is a chemical reaction process that covalently bonds PEG polymers to substrates, including molecules, macromolecules, biomass, polymers, dendrimers, particles, surfaces, etc.

Q: What is the difference between monodisperse PEG and polydisperse PEG?
A: Monodisperse PEG refers to polyethylene glycol with precise, non-continuous molecular weight (ie, the molecular weight is a fixed value, not a range), and is a pure compound with an exact molecular configuration. The molecular weights of polydisperse PEGs are described in terms of distribution ranges. Molecular weight distribution is usually confirmed by the dispersion coefficient (PDI).

Q: What is the difference between homobifunctional PEG and heterobifunctional PEG?
A: The homobifunctional PEG has the general structural formula X-PEG-X, that is, there are the same functional groups at both ends of the linear PEG chain; while the heterobifunctional PEG (X-PEG-Y) derivatives have 2 different functional groups group.

Q: How is the labeling degree (%) of fluorescently labeled polysaccharide products defined?
A: The degree of labeling (%) is obtained by dividing the number of covalently bound fluorescent dye or biotin molecules by the number of monomer units on the polysaccharide molecular chain. For example, 1.0 MOL % labeling means that 1 out of every 100 monomeric units on the polysaccharide chain is fluorescently labeled.

Q: How is the marketization of PEG modification technology?
A: There are more than ten PEG-modified drugs on the market that have been approved by the FDA. These products include PEG-modified enzymes, monoclonal antibodies, glycoproteins, cytokines, human growth hormone, nucleic acid aptamers, synthetic peptides and liposomes.

Q: What solvent can polyethylene glycol dissolve in?
A: PEG products are readily soluble in water and aqueous buffer solutions, with solubility up to several hundred milligrams per liter (mg/mL). PEG products are also very soluble in a variety of organic solvents, such as dichloromethane, chloroform, and are also very soluble, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), etc., also soluble when heated. In alcohol (methanol, ethanol, isopropanol), toluene and tetrahydrofuran (THF). DMF and DMSO can be used to prepare stock solutions of PEG reagents with water-sensitive functional groups that require the use of aqueous solvents, which are diluted or mixed with aqueous buffers, in the laboratory.

Q: What PEG products are particularly sensitive to light and oxygen?
A: PEG products containing carbon-carbon unsaturated bonds or easily oxidized bonds should be stored in the dark and air-isolated. These products include polyethylene glycol acrylates, PEG acrylamides, polyethylene glycol maleimides, PEG thiols, fluorescent PEGs, etc. Under strong light or exposure to air, these agents can polymerize to form insoluble aggregates glue, or lose activity or function.

Q: What is the difference between PEG NHS ester products?
A: Polyethylene Glycol-Carboxylic Acid and Polyethylene Glycol NHS Ester. These NHS esters can react with primary or secondary amines to form stable amide linkages. This reaction can be carried out in an organic solution with an organic substrate, or in an aqueous solution under near-neutral or weakly acidic or basic conditions. For PEGylated proteins or nanoparticles, a large excess of PEG NHS ester is often required due to the presence of competing hydrolysis reactions in aqueous solutions. The stability of NHS esters can be compared to the hydrolysis half-life (T1/2). To mitigate the effects of competing hydrolysis reactions, organic solvents such as amine-free, anhydrous DMF and DMSO can be used in combination with aqueous buffer solutions.

Q: How to store PEG products?
A: The product may be sensitive to temperature, light and humidity. Once shipped, it should be stored in a low temperature freezer at -15°C or lower. With the exception of some very small molecular weights, the product is in the form of a dry powder. Protect from light, especially UV light. Before opening for use, thaw slowly to room temperature to avoid moisture absorption. For long-term storage, it is recommended that the product be stored as a dry powder, not in any other solution form. If it must be stored in solution, be sure to pre-degas and dry the solvent.