Biomedical Engineering Reference
In-Depth Information
molecular level; they help recognize abnormalities such as fragments of viruses, precancerous cells,
and disease markers that cannot be detected by conventional methods. Nanoparticulate imaging
contrast agents have also been shown to improve the sensitivity and specificity of magnetic reso-
nance imaging [6]. Overall, nanoparticles offers numerous advantages such as better solubility and
drug dissolution rate, improvement in the absorption profile and bioavailability of drug, allowing
site-specific targeting of drugs, allowing controlled drug release, providing effective and/or easier
routes of administration, reducing therapeutic toxicity, prolonging the effect of drug in target tissue,
improving the stability of the drugs against chemical and enzymatic degradation, and subsequently
lowering healthcare costs.
Polymeric nanoparticles
(PNs) are prepared using naturally occurring, chemically modified, or
synthesized polymers. Polymer-based nanoparticles include PNs, micelles, and dendrimers. In these
nanoparticles, drug can either be physically entrapped within the polymer or covalently bound to
the polymer matrix depending on the preparation method. Therefore, the compounds formed may
have a structure like that of capsules (PNs), amphiphilic core/shell (polymeric micelles), or hyper-
branched macromolecules (dendrimers) [7].
Solid lipid nanoparticle
(SLN) is a type of nanoparticle drug delivery system that uses various
lipids to incorporate drug molecules. SLNs can incorporate both hydrophilic and lipophilic drugs
[2,8]. SLNs are an ideal drug delivery system without using organic solvents and their ability to
encapsulate the drug within its lipid matrix, allowing for sustained drug release.
Overall, pharmaceutical nanoparticles offer number of advantages and appear to be the future of
drug industry. Owing to the significant increase in their usage, it is very important to closely look
at the toxicity associated with the use of nanoparticles. This chapter discusses PNs and SLNs and
focuses on the toxicities associated with the use of these nanoparticles.
7.2 PREPARATION AND CHARACTERIZATION TECHNIQUES FOR POLYMERIC
AND SOLID LIPID NANOPARTICLES
PNs and SLNs can be prepared by using various techniques. Figure 7.1 shows different preparation
and characterization techniques for these systems. These preparation and characterization techniques
are similar to pharmaceutical nanoparticles and involve solution preparations such as nanosuspen-
sions or emulsion utilizing polymers/lipids. These solution preparations can be characterized for par-
ticle size, zeta potential, stability, and so on. In most of the cases, the solution preparation is converted
to solid state by removing water/solvent using freeze drying or solvent evaporation. Furthermore,
these systems are characterized for stability in solid state. Techniques such as PCS, Cryo-FESEM,
AFM, p-XRD, DSC, and TGA were used extensively for the characterization of nanoparticle sys-
tems. Tables 7.1 and 7.2 list some examples of PNs and SLNs prepared using various techniques.
7.3 NANOTOXICITY OF POLYMERIC AND SOLID LIPID NANOPARTICLES
Since the last decade, the use of nanoparticles has been explored considerably as a novel drug deliv-
ery system for almost all the pathological conditions. However, less emphasis has been given to study
the interaction of nanoparticles with the biological systems. Nanotoxicology is a field of research
that primarily focuses on the interactions of nanostructures with biological systems, particularly
exploring the effects on the physical and chemical properties (e.g., size, shape, surface chemistry,
composition, and aggregation) of nanostructures with the induction of toxic biological responses.
Recently, Keck and Müller [37] classified nanoparticles into four different classes (I-IV) from abso-
lutely “no” risk to “high” risk. The classification is based on the physical attribute (the nanoparticles
size (>/< 100 nm)) and the chemical behavior (such as the size-related differences in interaction
with human cells, and on biodegradability/nonbiodegradability in the body) of the nanoparticles.
By superimposing additional criterions such as biocompatibility (B) and nonbiocompatibility (NB)
