Biomedical Engineering Reference
In-Depth Information
so that they can make complex with the negatively charged DNA. Out of these,
DOTAP was found better cationic lipid as the higher zeta potential and smaller
particle size was observed (Carbone et al. 2012). Different compositions are
designed to make cationic SLN for gene delivery some of them are mentioned in
the Table
4
:
6.3.3 SLN for RNA Interference
RNA interference is proven to be very powerful technique for silencing the
specific genes by introducing small intracellular RNA (siRNA) or miRNA.
Therapeutics based on RNAi pathways have high potential to treat a wide range
of diseases such as autoimmune diseases, cancer, viral infections and so on (Davis
et al. 2010). This process was initially studied in flies and worms (
Caenorhabditis
elegans
) and later mammalian cells were exposed to the artificially synthesized
siRNA to see the gene silencing effects without any immune rejection. This
approach is useful because it can circumvent the problems associated with the
small molecule inhibitors and monoclonal antibodies (MAbs) generally utilized
in the treatment of cancer (Pecot et al. 2011). The mechanism of RNAi involves
the complexation of dsRNA to a protein complex known as RISC (RNA-induced
silencing complex) leading to the inhibition of conversion of mRNA into protein
(Piao et al. 2012).
But there are some obstacles in using siRNA as cancer therapeutic agent such
as rapid RNase mediated degradation, short half-life, immunogenic toxicity and
inefficient delivery to the targeted cells. In specific to the neural cells, it is very
difficult to use siRNA for gene silencing because of its toxicity and low transfec-
tion efficiency. Therefore an appropriate delivery vehicle would be highly valuable
for the efficacy of these kinds of therapeutics. SLN proves to be highly efficient
nanocarrier for siRNA delivery overcoming the above mentioned problems. Some
of the examples are mentioned in the Table
5
:
6.3.4 Photodynamic Therapy Using SLN
Photodynamic therapy is a kind of treatment that utilizes special drugs known
as photosensitizing agents which are being activated by light to generate reac-
tive oxygen species killing the cancerous cells. This therapy is highly beneficial
in the treatment of various kinds of cancers. Generally the photosensitizers are
highly hydrophobic in nature which leads to the aggregation when administered
inside the biological systems. This greatly reduces the efficiency of photody-
namic therapy which further can be enhanced by encapsulating the photosensitiz-
ers in a suitable carrier like SLN and other various lipid based nanovehicles. In
one study, hypericin-loaded solid lipid nanoparticles (Hy-SLN) were prepared to
overcome the problems associated with the photosensitizers. After encapsulation
hypericin was found to be more dispersible in aqueous system. Along with better
