Biomedical Engineering Reference
In-Depth Information
an amount of free tamoxifen approximately equal to that encapsulated in
500 mg ml
− 1
of nanospheres was used in the incubation medium, instead of the
drug-loaded nanospheres, cell viability was much higher (
67%). The lower cyto-
toxicity observed when the free drug was used was attributed to the low solubility
of free tamoxifen in the medium, and also to its high binding affi nity to plasma
proteins in the growth medium [99]. On the other hand, uptake of the drug-loaded
nanospheres by the MCF-7 cells may lead to tamoxifen being released directly
inside the cells, thus increasing the intracellular tamoxifen concentration and
hence its anticancer activity.
∼
10.4.3.3
Chitosan Loaded with Cefradine
Magnetic Fe
3
O
4
nanoparticles, a model drug and fl uorescent CdTe quantum dots
(QDs) have been encapsulated into chitosan nanoparticles [100]. Chitosan, a linear
polysaccharide comprising glucosamine and
N
-acetyl glucosamine linked in a
β
(1-4) manner, has been identifi ed to have potentially very useful biomedical
applications [101]. The preparation of magnetic and fl uorescent chitosan nanopar-
ticles containing a hydrophilic drug, cefradine, was conducted in a water-in-oil
microemulsion system containing cyclohexane, Triton X-100, and
n
- hexanol. The
Fe
3
O
4
nanoparticles, CdTe QDs and cefradine were dispersed in 0.1% chitosan (in
1 vol.% acetic acid) solution, and the mixed solution was added to the microemul-
sion system. Glutaraldehyde was used as a crosslinking agent, and the degree of
crosslinking tailored the size, morphology, surface properties and drug release
behaviors of the nanoparticles. With a crosslinking time of 12 h, the hydrodynamic
diameter was
107 nm and the zeta potential 5 mV. With shorter crosslinking
times, the nanoparticles were aggregated with a higher zeta potential. The
M
s
was
∼
∼
82 wt%
achieved. For nanoparticles prepared with a crosslinking time of 3 h, approxi-
mately 42% of the drug was released during the fi rst hour in a pH 7.4 release
medium, while the total amount released was 90% in 40 h. When a crosslinking
time of 12 h was used, the drug showed a more uniform release rate, with 79%
being released in a pH 7.4 release medium within 84 h.
11 emu g
− 1
, and a drug encapsulation effi ciency of
>
99% and loading of
∼
10.4.3.4
PECA or PCL Loaded with Cisplatin or Gemcitabine
Poly(ethyl - 2 - cyanoacrylate) ( PECA ), which has the characteristics of a fast degrada-
tion rate, low toxicity, and high compatibility with biological systems, has been
used to prepare drug- and magnetite-loaded nanospheres [102] by an interfacial
polymerization method. The magnetite used was from a commercial source, and
two types of anticancer drug were investigated: (i) cisplatin, which is used to treat
cancer of the ovary, testis, bladder, head and neck; cisplatin is insoluble in water
but soluble in most organic solvents; and (ii) gemcitabine, which is most often
used to treat non-small-cell lung cancer, pancreatic and bladder cancer; gem-
citabine is soluble in water, slightly soluble in methanol, and practically insoluble
in ethanol and polar organic solvents.
A mixture of ethyl-2-cyanoacrylate monomer, magnetite and drug in propylene
carbonate constituted the oil phase, while the water phase contained 15% stabilizer
