Polyethylene glycol

Polyethylene glycol

Polyethylene glycol (PEG; /ˌpɒliˈɛθəlˌiːn ˈɡlaɪˌkɒl, -ˈɛθɪl-, -ˌkɔːl/) is a polyether compound derived from petroleum with many applications, from industrial manufacturing to medicine. PEG is also known as polyethylene oxide (PEO) or polyoxyethylene (POE), depending on its molecular weight. The structure of PEG is commonly expressed as H−(O−CH2−CH2)n−OH.[3]

Uses

Medical uses

•    Pharmaceutical-grade PEG is used as an excipient in many pharmaceutical products, in oral, topical, and parenteral dosage forms.[4]
•    PEG is the basis of a number of laxatives (as MiraLax, RestoraLAX, etc.).[5] Whole bowel irrigation with polyethylene glycol and added electrolytes is used for bowel preparation before surgery or colonoscopy or for children with constipation. The name may be followed by a number which represents the average molecular weight (e.g. macrogol 3350, macrogol 4000 or macrogol 6000).
•    The possibility that PEG could be used to fuse axons is being explored by researchers studying peripheral nerve and spinal cord injury.[5]
•    An example of PEG hydrogels (see Biological uses section) in a therapeutic has been theorized by Ma et al. [7] The gel with encapsulated stem cells was to be injected into the site of disease and crosslinked to create the microenvironment required for the stem cells to function.
•    PEGylation of adenoviruses for gene therapy can help prevent adverse reactions due to pre-existing adenovirus immunity.[8]
•    A PEGylated lipid is used as an excipient in both the Moderna and Pfizer–BioNTech vaccines for SARS-CoV-2. Both RNA vaccines consist of messenger RNA, or mRNA, encased in a bubble of oily molecules called lipids. The US CDC stated that in their jurisdiction six cases of "severe allergic reaction" had been recorded from more than 250,000 vaccinations, and of those six only one person had a "history of vaccination reactions".[12]

Chemical uses

The remains of the 16th century carrack Mary Rose undergoing conservation treatment with PEG in the 1980sTerra cotta warrior, showing traces of original color
•    Polyethylene glycol is also commonly used as a polar stationary phase for gas chromatography, as well as a heat transfer fluid in electronic testers.
•    PEG is frequently used to preserve waterlogged wood and other organic artifacts that have been salvaged from underwater archaeological contexts, as was the case with the warship Vasa in Stockholm,[13] and similar cases. In addition, PEG is used when working with green wood as a stabilizer, and to prevent shrinkage.[14]
•    PEG has been used to preserve the painted colors on Terracotta Warriors unearthed at a UNESCO World Heritage site in China.[15] These painted artifacts were created during the Qin Shi Huang (first emperor of China) era.The German Bavarian State Conservation Office developed a PEG preservative that when immediately applied to unearthed artifacts has aided in preserving the colors painted on the pieces of clay soldiers.[16]
•    PEG is often used (as an internal calibration compound) in mass spectrometry experiments, with its characteristic fragmentation pattern allowing accurate and reproducible tuning.
•    PEG derivatives, such as narrow range ethoxylates, are used as surfactants.
•    PEG has been used as the hydrophilic block of amphiphilic block copolymers used to create some polymersomes.[17]
•    PEG is a component of the propellent used in UGM-133M Trident II Missiles, in service with the United States Navy.[18]
•    PEG has been used as a solvent for aryl thioether synthesis.[19]

Biological uses
•    An example study was done using PEG-diacrylate hydrogels to recreate vascular environments with the encapsulation of endothelial cells and macrophages. This model furthered vascular disease modeling and isolated macrophage phenotype's effect on blood vessels.[20]
•    PEG is commonly used as a crowding agent in in vitro assays to mimic highly crowded cellular conditions.[21] Although polyethylene glycol is considered biologically inert, it can form non-covalent complexes with monovalent cations such as Na+, K+, Rb+, and Cs+, affecting equilibrium constants of biochemical reactions.[22][23]
•    PEG is commonly used as a precipitant for plasmid DNA isolation and protein crystallization. X-ray diffraction of protein crystals can reveal the atomic structure of the proteins.
•    In microbiology, PEG precipitation is used to concentrate viruses. PEG is also used to induce complete fusion (mixing of both inner and outer leaflets) in liposomes reconstituted in vitro.
•    Gene therapy vectors (such as viruses) can be PEG-coated to shield them from inactivation by the immune system and to de-target them from organs where they may build up and have a toxic effect.[24] The size of the PEG polymer has been shown to be important, with larger polymers achieving the best immune protection.
•    PEG is a component of stable nucleic acid lipid particles (SNALPs) used to package siRNA for use in vivo.[25][26]
•    In blood banking, PEG is used as a potentiator to enhance detection of antigens and antibodies.[5][27]
•    When working with phenol in a laboratory situation, PEG 300 can be used on phenol skin burns to deactivate any residual phenol.[28]
•    In biophysics, polyethylene glycols are the molecules of choice for the functioning ion channels diameter studies, because in aqueous solutions they have a spherical shape and can block ion channel conductance.[29][30]

Commercial uses

•    PEG is the basis of many skin creams (as cetomacrogol) and personal lubricants.
•    PEG is under investigation for use in liquid body armor, and in tattoos to monitor diabetes.[31]
•    Polymer segments derived from PEG polyols impart flexibility to polyurethanes for applications such as elastomeric fibers (spandex) and foam cushions.
•    In low-molecular-weight formulations (e.g. PEG 400), it is used in Hewlett-Packard designjet printers as an ink solvent and lubricant for the print heads.
•    PEG is used as an anti-foaming agent in food and drinks[32] – its INS number is 1521[33] or E1521 in the EU.[34]

Industrial uses

•    A nitrate ester-plasticized polyethylene glycol (NEPE-75) is used in Trident II submarine-launched ballistic missile solid rocket fuel.[35]
•    Dimethyl ethers of PEG are the key ingredient of Selexol, a solvent used by coal-burning, integrated gasification combined cycle (IGCC) power plants to remove carbon dioxide and hydrogen sulfide from the syngas stream.
•    PEG has been used as the gate insulator in an electric double-layer transistor to induce superconductivity in an insulator.[36]
•    PEG is used as a polymer host for solid polymer electrolytes. Although not yet in commercial production, many groups around the globe are engaged in research on solid polymer electrolytes involving PEG, with the aim of improving their properties, and in permitting their use in batteries, electro-chromic display systems, and other products in the future.
•    PEG is injected into industrial processes to reduce foaming in separation equipment.
•    PEG is used as a binder in the preparation of technical ceramics.[37]

Entertainment uses

•    PEG is used to extend the size and durability of very large soap bubbles.
•    PEG is the main ingredient in many personal lubricants.[citation needed] (Not to be confused with propylene glycol.)
•    PEG is the main ingredient in the paint (known as "fill") in paintballs.