*6.1. Nanoencapsulation*

Nanoencapsulation is a nanostructured drug delivery system (10–1000 nm [95]) that can be loaded with small molecules or macromolecules, thus acting as a vehicle for chemotherapeutic drugs. Such materials are able to transport chemotherapeutic molecules to the desired area, increasing the drug concentration, to be subsequently released in a controlled manner. A grea<sup>t</sup> number of nanoformulations—such as liposomes, micelles, nanoemulsions, and polymeric nanoparticles, among others—have been reported as drug delivery systems to be applied in cancer treatment [96–99].

Nanoencapsulation can be performed to generate two categories of nanodevice (see Figure 5), nanocapsules and matrixial nanomaterials. In the nanocapsules group, the chemotherapeutic drug

is surrounded by a wall or shell material to generate spheres or irregular nanocapsules where the chemotherapeutic drug can be mononucleated (a single core) or polynucleated (multicore) [100–102].

**Figure 5.** Nanodevices for the encapsulation of chemotherapeutic drugs/antioxidants.

Matrixial nanomaterials are more varied. Generally, the bioactive compound (chemotherapeutic drug) is embedded or superficially adsorbed in a polymer matrix. The polymer matrix can be configured in different forms, nanospheres, irregular nanoparticles, and nanofibers, among others [103–105]. Likewise, the nanoparticle may or not may be coated by another polymer. The nanoparticle can be solid or nanostructured by fibers [106,107].

The techniques used for achieving nanoencapsulation are complex. This is mainly due to the difficulty in attaining the complex morphology of the capsule and core material and the demands of controlling the release rate of the nanocapsules [108]. Various techniques have been developed and used for nanoencapsulation purposes. For instance, emulsification, coacervation, inclusion complexation, solvent evaporation, nanoprecipitation, and supercritical fluid techniques can produce capsules in the nanometer range (10–1000 nm) [95,108]. Most of the documents regarding encapsulation relate to particles between 100 and 1000 nm. However, there also some reports with capsules ranging from 10 to 100 nm.
