The key to the preparation of nanoparticles is to control the particle size, obtain narrow and uniform particle size distribution, reduce or eliminate particle agglomeration, and ensure effective, safe and stable drug use. There is no doubt that production conditions, cost and output are also comprehensive factors. At present, the preparation techniques of nanoparticles can be divided into three categories, namely, mechanical pulverization, physical dispersion and chemical synthesis. In addition, some traditional mechanical crushing equipment has been improved, such as vibration mill, airflow mill, ultrasonic sprayer and so on. Some new mechanical crushing technologies, such as supercritical fluid technology, supercritical fluid-liquid film ultrasonic technology, high pressure homogenization-cavitation blasting technology and other advanced technologies and related equipment have also been developed.
Different preparation techniques and processes are suitable for the preparation of different kinds of nanoparticles. For example, the melt dispersion method is mainly used to prepare solid lipid nanoparticles (SLN); Physical methods such as solvent evaporation, emulsification/solvent diffusion can be used to prepare nanosuspensions or pseudolatexes. Using polylactic acid (pla), poly (lactide-co-glycolide), polyamino acid and chitosan as hydrophobic segments, and polyethylene glycol (peg) and polyoxyethylene (PEO)- polyoxypropylene as hydrophilic segments, block * * * polymers or grafted * * * polymers with surface activity were synthesized and dissolved in water to form nano-micelles. The aqueous solution containing chitosan-peg block polymer was mixed with the aqueous solution of polyanionic compound-sodium tripolyphosphate, and condensed into nanoparticles due to the combination of opposite charges.
Nanodrug delivery
The "rapid nano-precipitation" technology developed by researchers at Princeton University in China has reached the stage of commercial application, which can mix drugs and packaging materials to produce 100 ~ 300 nm particles. This particle can not only stay in the lung without causing the lung's self-defense system to work, but also enhance the effect of inhalation administration and the efficacy of needle-free drug delivery system to deliver vaccines. This technology is to collide two liquids in the form of liquid flow in a limited area, one of which is an organic solvent in which drugs and polymers are dissolved, and the other is water. When two liquids meet, hydrophobic drugs and polymers precipitate and separate out solutions. Polymer molecules are directly attached to the surface of drug particles as hydrophobic parts, while hydrophilic parts are wrapped on the surface of drug in the form of extending to solution. The particle size of nanoparticles can be controlled by adjusting the concentration of solution and mixing speed. On the one hand, the hydrophilic part of polymer molecules can prevent the aggregation of particles, on the other hand, it can prevent the recognition of immune system, so that drug particles stay in the blood circulation.