**10. Electrospray**

In a general process, a solution of the matrix, which constitutes the particles, is contained in a syringe, with a metal capillary connected to a high-voltage power supply, working as an electrode. A metal foil collector is placed opposite the capillary as a counter electrode (Figure 7). Depending on the properties of the liquid, the flow rate and the voltage applied can be modulated.

The cone-jet mode is the method used to prepare nanoparticles, in which liquid emerging at the nozzle forms hemispherical drops because of the surface tension. By increasing the electrical field, the hemispherical drops can be changed to a conical shape, which breaks up into highly charged droplets. By selecting suitable conditions, droplets can be produced with a close size distribution and nano-or micrometer size range. Particles can be formed by evaporating the solvent from the droplets produced travelling through the electrical field.

The electrospray method has been employed to prepare monodisperse lipid-based nano-and microparticles: lipid has been dissolved in aliphatic alcohols and this solution has been used for particles production. Particle shape and size depend on the solvent and excipients used and on the applied voltage [54,55].

**Figure 7.** Scheme of electrospray apparatus
