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Polyethylene glycol

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Polyethylene glycol, often called PEG, is a versatile polyether compound. It is derived from petroleum and is used in many different fields. You can find it in industrial manufacturing, medicine, and even in your own home. Depending on its molecular weight, it is also known by other names. Scientists call it polyethylene oxide (PEO) or polyoxyethylene (POE).

SArfus PEO.3D
SArfus PEO.3D

The chemical structure of PEG is written as H−(O−CH2−CH2)n−OH. This formula describes how the molecules are linked together. PEG is often used to create hydrogels. A hydrogel is a substance that can hold a large amount of water. These gels serve as a functional form for many medical uses. PEG is also used as a stabilizer in various chemical processes.

Polyethylene glycol 400
Polyethylene glycol 400

In the medical field, PEG acts as a vital excipient. An excipient is an inactive substance that helps a drug work correctly. It can be used in oral, topical, or parenteral dosage forms. PEG is the primary ingredient in many laxatives, such as Macrogol. These products are often named by their molecular weight, like macrogol 3350 or 6000. It is also used for whole bowel irrigation before surgeries.

Polyethylene glycol 4000
Polyethylene glycol 4000

Modern medicine has found even more complex ways to use PEG. It is used in the process called PEGylation. This involves attaching PEG to molecules like adenoviruses for gene therapy. This coating helps prevent the immune system from attacking the treatment. PEGylated lipids are also used in the Moderna and Pfizer–BioNTech SARS-CoV-2 vaccines. In these vaccines, PEG coats tiny oily bubbles called lipids. This coating helps keep the messenger RNA, or mRNA, stable inside the body.

However, PEG is not without risks for some people. It can trigger allergic reactions, including anaphylactic shock. In the United Kingdom, regulators issued an advisory after some individuals had reactions. The US CDC reported six cases of severe allergic reactions from over 250,000 vaccinations. One study found that 72% of random blood plasma samples contained anti-PEG antibodies. This suggests that many people may have developed an immune response to PEG even without medical treatment.

Archaeologists use PEG to protect history from disappearing. When waterlogged wood is salvaged from underwater, it can warp or shrink as it dries. PEG replaces the water inside the wood to keep it dimensionally stable. This method was used to conserve the 16th-century ship, the Mary Rose.

MaryRose-conservation2
MaryRose-conservation2

It is also used for the Terracotta Warriors in China. When these clay soldiers are unearthed, their lacquer and paint can flake off in minutes. A special PEG preservative from Germany helps keep these ancient colors intact.

Terra Cotta Warriors, Guardians of China’s First Emperor 1
Terra Cotta Warriors, Guardians of China’s First Emperor 1

Scientific history was also changed by PEG. In 1984, César Milstein and Georges J. F. Köhler won a Nobel Prize. They used PEG to fuse different types of cells together. This process creates hybridomas, which are used to produce antibodies. PEG is also used in biophysics to study ion channels. Because PEG molecules are spherical in water, they can block the flow of ions. This helps researchers understand how tiny channels in cells work.

Beyond medicine, PEG has many industrial and commercial roles. It is used in skin creams, personal lubricants, and even toothpaste. In toothpaste, it acts as a dispersant to keep ingredients like xanthan gum distributed. It is even used to make large soap bubbles last longer. In heavy industry, PEG is used in solid rocket fuel for Trident II missiles. It is also used in power plants to remove carbon dioxide from gas streams.

Polyethylene glycol 400
Polyethylene glycol 400
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File:MaryRose-conservation2.jpg
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Terra Cotta Warriors, Guardians of...
File:SArfus PEO.3D.jpg
SArfus PEO.3D.jpg
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Polyethylene glycol 400.jpg
File:Polyethylene glycol 4000.jpg
Polyethylene glycol 4000.jpg
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