Single-Chain Polymer Nanoparticles for Application in Nanomedicine - Harnessing Biomaterials in Nanomedicine: Preparation, Toxicity, and Applications - page 22

2.1 Introduction
The role of nanoparticles in biomedicine has increased in recent
years, mainly due to their wide number of applications in the field
of nanomedicine. Advances in synthetic techniques have enabled
the preparation of particles ranging from a few nanometres up to
hundreds of nanometres over a wide range of materials.
Hence, inorganic nanoparticles are being exploited due
to their unique physical properties. Silver nanoparticles have
demonstrated to be active antibacterial agents. Hydroxyapatite
nanoparticles have been investigated due to their osteo-inductive
properties. Superparamagnetic properties of ferromagnetic and
ferrimagnetic nanoparticles are interesting for their application in
MRI, hyperthermia therapy, and biosensors. The optical properties
of quantum dots and gold nanoparticles are also a field of interest
for their application in imaging. And TiO 2 , silica, ZnO, and other
nanoparticles are also under development.
However, there is a growing concern over the toxicity of particles
of diff erent sizes, shapes, and composition. It is widely known that
the size and surface properties of nanomaterials determine their
interaction with biological systems, and as such, their potential
toxicity [1]. Diff erent types of nanoparticles have been shown to be
cytotoxic to human cells [2], induce oxidative stress [3], or induce an
immune response [4]. Nanoparticles can accumulate in lung tissue
after inhalation and translocate to the bloodstream [5]. Of particular
concern is their ability to enter neurons and cross the blood-brain
barrier [6].
However, even though there is a concern regarding the toxicity
of nanoparticles, and though it may seem contradictory, the use of
these nanoparticles could have applications in reducing the toxicity
of certain drugs and contrast agents. This could be done with
the design of multifunctional biodegradable and biocompatible
particles, specifically designed to improve the biodistribution and
target site accumulation of systematically applied therapeutics at
the pathological site, and so reducing the accumulation in healthy
organs and tissues. This would lead to an increase of the efficacy of
treatments and a reduction of the toxicity.
For this purpose, nanocarriers based on soft matter have
particularly interesting characteristics. The classification of those
systems is variable, depending on their nature. Some authors