Background and overview[1]
Polyethylene glycol is an excellent chemical melting agent used in protoplast fusion. It is a polymer of ethylene glycol, with the molecular formula HOCH2(CH2O·CH2)n CH2OH. It is a white yellowish waxy solid, soluble in water, and has a slight odor. There are a series of polymers with different relative molecular masses. Those with relative molecular masses between 200 and 6000 can be used as melting agents, but those with relative molecular masses of 1000 are better (liquid at this time). PEG has strong water solubility. In liquid media, the ether bonds on its molecular surface carry a weak negative charge. With the participation of Ca2+ ions, the positively charged surface proteins or Negatively charged glycoproteins are connected through Ca2+ bridges, causing cells to aggregate and fuse. In 50% PEG, free water disappears, which can lead to cell dehydration, resulting in changes in plasma membrane structure and cell fusion. The advantages of PEG used in cell fusion are: ① It has strong versatility and can be used in various cells of animals, plants and microorganisms; ② It is easier to prepare and control than Sendai virus; ③ It has stable activity and is easy to use. The disadvantages are: ① The effective concentration range is narrow (50% to 55%), but it is more toxic to cells at this time; ② The cell fusion process cannot be observed under the microscope; ③ The frequency of inducing hybrid cells is low (about 1× 10-5). In addition to being used as a melting agent, it can also be used to promote the uptake of exogenous transformed DNA by yeast, and can be used as a precipitating agent in clinical chemistry and an osmotic concentrate for aqueous solutions or suspensions such as serum. Polyethylene glycol linking agent can be used to modify various biological drugs. It can form formula materials through cationic lipophilic liposome nanoparticles, and it will be possible to instantly load targeting molecules and realize the mounting of any drug. It can be used to establish targeted The personalized drug library for cancer patients provides mature technical support.
Application
Many organic small molecule drugs are gradually adopting PEG modification technology and have made certain progress. Polyethylene glycol can modify small molecule drugs through polyethylene glycol linkers, which can transfer many of its excellent properties. Into the conjugate, the polymer has excellent biocompatibility, can be dissolved in tissue fluid in the body, and can be quickly excreted by the body without any toxic side effects. Therefore, its application in medicine has received widespread attention. , currently mostly anti-tumor drugs. In recent years, small molecule drugs that use PEG modification technology through polyethylene glycol linkers mainly include: paclitaxel, camptothecin, cytarabine, scutellarin, etc. PEG-modified small molecule drugs are still mainly related to the OH of the drug, NH2, COOH and other groups react, and the connection between small molecule drugs and PEG can be either a permanent connection or a prodrug. At present, the form of prodrug is more common.
Main reference materials
[1] Microbiology Dictionary
[2] Research progress on polyethylene glycol modification of drugs
