Biomedical Engineering Reference
In-Depth Information
which in aqueous solution arrange to form an outer hydrophilic layer and an inner hydrophobic
core. The miceller core can be loaded with a water-insoluble therapeutic agent. Liposomes are lipid
structures that can be made “stealth” by PEGylation and further conjugated to antibodies for target-
ing. Dendrimers are monodispersed symmetric macromolecules built around a small molecule with
an internal cavity surrounded by a large number of reactive end groups. Quantum dots are fluores-
cent nanocrystals that can be conjugated to a ligand and thus can be used for imaging purposes.
Ferrofluids are colloidal solutions of iron oxide magnetic nanoparticles surrounded by a polymeric
layer, which can be further coated with affinity molecules such as antibodies.
Source
: From Ref. [
42
].
19.7.3
Magnetic Nanoparticles in Oral Cancer Treatment
Magnetic nanoparticles are iron oxide particles sheathed with sugar molecules (
Figure 19.2
).
Therefore, these are not recognized by the immune system
[43]
. When these particles are brought
under the influence of an external magnetic field, they heat up the tumor cells and destroy them with-
out affecting the surrounding healthy tissues. A group of researchers have synthesized biodegradable
magnetic nanoparticles by using organic polymers and nanosized magnetites
[44]
. After the charac-
terization studies, an external magnetic field was used as a guidance system to direct the magnetic
nanoparticles to the specified part of the experimental setup. The results of such studies substanti-
ate the theory of targeting magnetic nanoparticles to specific areas of the human body by using an
external magnetic field. Iron oxide nanoparticles can also be coated with amino groups to achieve
cell-specific delivery of therapeutic agents, for example, to carcinomatous brain cells without unse-
lectively invading the whole brain. Magnetic drug targeting in treatment of squamous cell carcinoma
has shown to be effective with the advantage of no adverse clinical side effects. Antineoplastic/cancer
drug like Mitoxantrone
[45,46]
delivered through magnetic nanoparticles has been shown to be effec-
tive in treating squamous cell carcinoma. Organic-coated superparamagnetic iron oxide nanoparticles
(OC-SPIONs)
[47]
and ferrofluids (colloidal dispersion of magnetic nanoparticles)
[48]
have also
been proven to be excellent target-specific carriers of anticancer drugs for drug delivery to squamous
cell carcinoma cells when compared to the usual systemic administration.
19.7.4
Polymeric Micelles as Drug Delivery Systems
Polymeric micelles (
Figure 19.2
) serve as a novel drug delivery system due to their target specifi-
city and controlled release of hydrophobic anticancer drugs. PEG-based micelles are biocompatible
and biodegradable. Therapeutic use of hydroxycamptothecin (HCPT), a promising antitumor agent, is
limited by its poor solubility and rapid destruction. PEG-based amphiphilic block copolymer micelle
carriers possess significant potential for improving drug solubility and stability. When HCPT was
encapsulated in poly[ethylene glycol]-poly[gamma-benzyl-L-glutamate] (PEG-PBLG) micelles, the
antitumor effects of HCPT/PEG-PBLG micelles against oral squamous cell carcinoma
in vivo
were
concluded to be superior to those exerted by HCPT
[49]
. Polymeric micelles have also been evalu-
ated for photodynamic therapy
[50]
. The results showed that polymeric micelles were able to encap-
sulate and solubilize 5,10,15,20-tetrakis(meso-hydroxyphenyl)porphyrin (mTHPP), a photosensitizer,
at high loading densities with uniform size distribution. These micelles exhibited fluorescence and
photodynamic-therapy-mediated cytotoxicity against head and neck cancer cells
in vitro
. These stud-
ies demonstrate the potential of polymeric micelles as a novel drug delivery system in oral cancer
treatment.
