Single-Chain Polymer Nanoparticles for Application in Nanomedicine - Harnessing Biomaterials in Nanomedicine: Preparation, Toxicity, and Applications - page 23

diff erentiate between polymeric, non-polymeric, and biological
nanocarriers [7]. Polymeric nanocarriers include nano-conjugates,
polymer nanoparticles, micelles, dendrimers, or polyplexes, for
example. Non-polymeric nanocarriers consist on liposomes,
ethosomes, solid lipid nanoparticles, lipid nanocapsules, nano-
emulsions, and others. Finally, biological nanocarriers include viral
and bacterial vectors, erythrocytes, or stem cells.
Soussan and co-workers diff erentiate matrix systems and
vesicles depending on their morphology [8]. They divide them into
two categories: those that consist of solid nanoparticles, such as
polymer nanoparticles and dendrimers, and those that consist of
hollow spheres, such as nanocapsules or polymersomes, liposomes,
niosomes, or cationic vesicles.
Irrespective of their nature, size, or morphology, there are
interesting developments for a wide number of applications. In
particular, polymer nanoparticles are being mostly developed for
drug delivery [9], and there are a large number of examples of their
applications in many biomedical fields and pathologies. Examples
include HIV [7, 10, 11], cancer [12, 13], siRNA delivery [14], malaria
[15], Chagas [16], imaging agents [17], image-guided drug delivery
[18], and sensors and self-healing systems [19].
We have mentioned many nanoparticulate systems depending
on their nature and morphology. Size is also an important parameter.
If we focus on solid polymer nanoparticles, most of the examples
can be included in three diff erent systems: polymer nanoparticles,
micelles, and dendrimers.
Polymer nanoparticles (PNPs) are usually 20-100 nm in size
and can be composed of biodegradable or biostable polymers and
copolymers. For drug delivery applications, the active agent can be
(i) entrapped or encapsulated within the particle, (ii) physically
adsorbed on the surface, or (iii) chemically linked to the surface of
the particle [20-22]. Polymer nanoparticles can be divided into two
main families: nanospheres, which have a homogeneous structure
in the whole particle, and nanocapsules, which exhibit a typical
core-shell structure [23]. There are two main methods of synthesis:
those formed by in situ polymerisation in nanoemulsion systems
and those synthesised by preformed polymers. Polymer micelles
are nanostructures of a mean diameter of 20-50 nm that have been
utilized for improving aqueous solubility, intestinal permeability,
and disease site targeting of several drug molecules. Compared