Production methods for nanodrug particles using the bottom-up approach.

This review focuses on bottom-up processes such as precipitation (or crystallisation) and single droplet evaporation to produce nanoparticles containing largely pure therapeutics for pharmaceutical applications. Suitable precipitation techniques involve the use of high-gravity, confined impinging liquid jet mixing, multi-inlet vortex mixing, supercritical fluids, and ultrasonic waves. Droplet evaporation methods are spray-based, including nanospray drying, aerosol flow reactor method, spraying of low-boiling point solvent under ambient conditions and electrospraying of low-electrical conducting solutions. A key to the success of yielding stable nanoparticles in these various techniques is to control the particle growth kinetics through evaporation rate of the droplets or mixing rate during precipitation.