Nanopowder generally refers to powder or particles with a particle size of fewer than 100 nanometers. It is a solid particle material in an intermediate state between atoms, molecules and macroscopic objects. Nano-dispersion refers to the dispersion of one or several kinds of nanoparticles in another substance to form a nanoparticle dispersion. Due to the large specific surface area and high surface energy of nano-powders, in the process of preparation and use, particles are easily agglomerated to form secondary particles, which increase the particle size and lose the functions of nano-particles. Therefore, it is necessary to disperse the nanopowder.
Figure 1. Synthetic route of DOX–PLGA conjugate by an ester linkage.
The preparation of the nano-dispersion system includes physical dispersion method (such as ultrasonic dispersion method, mechanical dispersion method, high energy treatment method, etc.) and chemical reaction method (such as dispersant dispersion method, surface chemical modification method) and so on.
Figure 2. Preparation of silica nano-dispersion by surface chemical modification method.