There are currently two vaccines on the market worldwide for mRNA, a type of single-stranded RNA that carries genetic information encoded by proteins and is translated directly into proteins by ribosomal machines. If it is translated into spike glycoprotein (S protein) in the body, it triggers an immune response. This is because the fatty membrane that wraps the new Guanbing virus particles has an S protein on its surface, and it is through this protein that the virus binds to angiotensin-converting enzyme 2 (ACE2) on the cell surface to invade human cells after entering the body.
Scientists have faced a number of technical challenges in developing the new vaccine. Zaida's problems are that it is unstable, degrades easily, and has a short half-life. There are two main ways to deal with this problem: one is deep cryopreservation so that it can prolong its stable state as long as possible in a frozen environment; The other is to modify the mRNA sequence during the development process, including the optimization of each characteristic sequence region, or the chemical structure optimization of the base. The half-life of the vaccine can be greatly extended by modification, allowing it to remain at -20C for a longer time.
Therefore, the stability of lipid nanoparticles (LNP) preparation is very important at low temperatures. Sucrose was used as a vaccine stabilizer and cryoprotection to prevent lipid stickiness in the two mRNA vaccines.
Although it is a simple and common basic excipient, it plays a key role in biological vaccine products, especially mRNA** vaccines that need to be preserved at a relatively low temperature. The addition of sucrose can reduce the crystallization temperature and the amount of freezing of the water phase, and the interface film formed by the adsorption of sugar molecules on the oil-water interface can increase the steric resistance and electrostatic repulsion between droplets. Therefore, low temperature (freeze-thaw) stability and mRNA stability can be improved by adding sucrose. Trehalose also performs these functions, and in some cases better.
Due to the particularity of mRNA vaccine, the quality and production process is particularly high, and the quality of raw and auxiliary materials used in production will directly affect the production and quality of the vaccine. In order to ensure the sterility of vaccine injections and a load of harmful substances, enterprises should consider the corresponding control of raw and auxiliary materials from the source; For some varieties that are not suitable for pyrogen removal in the process, the content of harmful substances in bacteria of excipients should be strictly controlled, or the excipients should be separately treated with pyrogen first. For special products such as mRNA and vaccine, sucrose and trehalose for injection with low internal harmful substances should be selected as far as possible to ensure product quality and reduce risks. Whether for injection or freeze-drying agent, sucrose with high purity, low internal harmful substances and high-cost performance of AVT not only meets the requirements of the pharmacopeia of various countries but also exceeds the requirements of USP and EP in key indicators such as bacterial harmful substances and microbial limits, which can ensure production efficiency and the quality and stability of vaccines.