Biomedical Engineering Reference
In-Depth Information
useful for developing new bioscaf olds, photocatalysts, sensors, and drug
delivery vehicles [146]. Amoxicillin nanobelts, nanoi bers, nanoparticles,
and microparticles can be obtained by changing the pH in solutions of
amoxicillin sodium, and controllable growth of amoxicillin can be realized
[147]. Electrospinning is a simple and versatile technique that can produce
a macroporous scaf old comprising randomly oriented or aligned nanoi -
bers. Endowed with both topographical and biochemical signals such elec-
trospun nanoi brous scaf olds may provide an optimal microenvironment
for the seeded cells for biomedical applications such as drug delivery and
tissue engineering [148].
6.10 Nanoshells
A gold-coated silica nanosphere-type of nanoshells were embedded in a
drug-containing tumor-targeted hydrogel polymer and then injected into
the body, where they accumulate near tumor cells. As treated with an infra-
red laser, the nanoshells selectively absorb a specii c infrared frequency,
melting the polymer and releasing the drug payload at a specii c site.
Nanoshells might prove useful in treating diabetes—a patient would use a
ballpoint-pen-sized infrared laser to heat the skin site where the nanoshell
polymer had been injected, releasing a pulse of insulin. Unlike injections,
which are taken several times a day, the nanoshell-polymer system could
remain in the body for months. h e stimuli responsive polymeric cap-
sules and nanoshells are formed via the layer-by-layer (LbL) approach for
multifunctionality and responsiveness to stimuli like physical (light, elec-
tric, magnetic, ultrasound, mechanical, and temperature), chemical (pH,
ionic strength, solvent, and electrochemical) and biological (enzymes and
receptors).
Cancer is a leading cause of death. Conventional methods of treating
cancer involve surgical removal of easily accessible tumors, radiation ther-
apy, and chemotherapy, with no full treatment. Nanoshells are optically
tunable core/shell nanoparticles that can be fabricated to strongly absorb
in the near-infrared (NIR) region where light transmits deeply into tissue.
When injected systemically, these particles have been shown to accumulate
in the tumor due to the enhanced permeability and retention (EPR) ef ect,
and induce photothermal ablation of the tumor when irradiated with an
NIR laser [149]. Current modalities of diagnosis and treatment of cancer
are based on nanoparticles using l uorescent materials, molecular research
tools and drugs with targeting antibodies as contrast agents. Paramagnetic
nanoparticles, quantum dots, nanoshells and nanosomes are a few of the
