If used in the pre-treatment of medicinal solutions (mostly in traditional Chinese medicine injections), it is convenient for dialysis (add an appropriate amount of gelatin solution to the medicinal solution to combine tannins and proteins into larger molecules for removal) . Used for injectable implants, biodegradable polymers as the backbone of implantable or injectable sustained-release preparations have been the direction of vigorous research by domestic and foreign scholars in the past 20 years. This type of polymers includes two major categories: ① Natural polymers , such as gelatin, dextran, albumin, chitin, etc. ②Synthetic polymers, such as polylactic acid, polylactide, polylactic-glycolic acid (PLGA), polylactide-glycolide (PLCG), polycaprolactone, polyhydroxybutyric acid, etc. It is used for liposome injection. After the drug and gelatin form a complex, the liposome is prepared by high-speed homogenization and dispersion method for injection. Nanocapsule injections, because the nanocapsule particles are extremely fine, can be quickly dispersed in water to form a transparent colloid dispersion system, which is suitable for the preparation of injections and can also be used for intravenous injection. nanocapsules during storage. More stable than lipids. It can be made into freeze-dried powder for storage, and can be restored to its original dispersed state by adding it for injection without shaking before use. (Nanocapsules or nanoparticles are also a kind of drug carrier. Its structure is similar to microcapsules, but its particle size is much smaller than that of microcapsules. It is dispersed in water to form an opalescent dispersion system. Molecular substances that resemble colloidal ions are made of natural polymer materials such as gelatin, albumin, and fiber. The diameter of the nanogel is approximately 10-100 μm. The single coagulation method used to prepare microgel capsules is similar to that of microsphere injection. Microspheres are gel microspheres made of suitable polymer materials and contain drugs. The particle size of the balls is very small and they are often suspended in oil. For example, 5-fluorouracil is in 20% gelatin, with a content of 16.8 mg per ml. Add injection (such as sesame oil), heat to 50°C, and mix the two phases (i.e., injection oil and 5-fluorouracil gelatin glue). Evenly, use ultrasonic treatment in a 70°C water bath to disperse the drug-containing gel in the oil. The gel particle size is 1-3mm. For example, use polyacetyl esters of sorbitol hemioleate-graded castor oil. Stabilizer can increase the stability of microspheres. The fluorouracil in fluorouracil microspheres is dispersed in the network structure of gelatin, and the drug is not wrapped in a microcosm shape. Another patent introduces the use of poly-lactic acid Poly (DL-laeticacid) as the capsule material for packaging microspheres. Its structure is similar to micro capsules. A drug is dispersed in a toluene solution of polyracemic lactic acid, and an alcohol phase separation agent is added under stirring to precipitate microspheres.