General procedure of the production of nano and microparticles by the aerosol flow reactor method

The general procedure of the production of nano and microparticles by the aerosol flow reactor method is presented in Figure 1. Materials such as drug, polymer, and/or other excipients are dissolved in a solvent like water and ethanol that are most commonly used solvents. This starting solution is atomized with an appropriate droplet generator. The droplets are carried to a heated tubular laminar flow reactor with the aid of a dry gas or saturated gas. Allowing to use variable flow rates as well as temperatures in the reactor the droplet drying and residence time in the reactor can be fixed. Possible molecular rearrangements such as self-assembling and crystallization occur in this section. Dry aerosols are diluted by large volume of dry gas downstream the reactor to avoid solvent recondensation and wall deposition. Subsequently, the particles are collected by a collector that is suitable for the particular size of the particles.

Particle size and size distribution are determined directly from a gas phase with low-pressure impactors and a differential mobility analyzer (DMA). Particle morphology is observed by a scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Moreover, the crystallinity of the materials can be detected by TEM.

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