Biomedical Engineering Reference
In-Depth Information
Preparation and
characterization of
PNs and SLNs
Characterization of
PNs and SLNs
PNs preparation
methods
SLNs preparation
methods
Analytical
characterization
In vitro
analysis
Nanoprecipitation
High-pressure
homogenization
a. Hot homogenization
b. Cold homogenization
Particle size
and zeta
potential
Emulsification-
solvent evaporation
Drug loading
Emulsification-
solvent diffusion
Ultrasonication/
high-speed
homogenization
Degree of
crystallinity and
lipid/polymer
modification
Drug
entrapment
Emulsification-
salting out
Drug release
studies
Microemulsion-
based method
Co-existence
of additional
structures and
dynamic
phenomena
Layer-by-layer
synthesis or
polymerization
Solvent
emulsification/
evaporation
Using supercritical
fluids
Double emulsion-
based method
FIGURE 7.1
(
See color insert.
) Preparation and characterization techniques of PNs and SLNs.
of the nanoparticle surface, the classification is further extended into eight total classes from I-B
(best tolerated) to IV-NB (highest potential risk). Nanoparticles such as nanoemulsions, liposomes,
and drug nanocrystals in the size range from 100 to 1000 nm are classified into low-risk class I.
Nanoparticles possessing medium risk either due to their size or nonbiodegradability are classified
into class II and class III. The highest toxicity risks possess nanoparticles of class IV. They are
<100 nm and can therefore access all cells. On top they are nonbiodegradable [37].
7.3.1 N
aNotoxIcIty
p
oteNtIal
of
pN
s
aNd
slN
s
Pharmaceutical PNs and SLNs can vary in size ranges from 50 to 1000 nm and thus can be consid-
ered to possess low to high risk in terms of toxicity assessment [37]. Polymers used in preparing PNs
can be biodegradable or nonbiodegradable, whereas lipids used in the SLN are usually a mixture of
lipids and can show polymorphism. Further, the preparation of nanoparticles requires the drug and
polymers/lipids to go through various unit operations, including melting, mixing, interaction with
water, solvents, and so on [2]. The transformation/degradation of these inert polymers/lipids can
leads to toxicity. Polymer and lipids used in the preparation of nanoparticles are considered to be safe
although their toxicity has not been studied extensively. SLNs are usually made up of physiological
