Nanotechnology in Drug Delivery
If your drug use consists of an occasional aspirin, you may not see the
need for serious work on drug delivery. But if you were diabetic, having
to inject insulin several times a day, or a cancer patient experiencing
debilitating side effects from your treatment, the benefits of improved
drug delivery could change your life.
Perhaps the most publicized use of nanotechnology in drug delivery under
development is the use of nanoparticles to deliver drugs to cancer
Particles are engineered so that they are attracted to
diseased cells, which allows direct treatment of those cells. This
technique reduces damage to healthy cells in the body.
However, that’s just the tip of the drug delivery iceberg: there
are a number of other ways that nanotechnology can make the delivery of
drugs more efficient and potentially less unpleasant for the patient.
Some techniques are only imagined, while others are at various stages of testing, or actually being used today.
The following survey of nanomedicine applications in drug delivery
introduces many of these techniques.
Nanotechnology in Drug Delivery - Cancer:
Many researchers attach ethylene glycol molecules to nanoparticles that deliver
therapeutic drugs to cancer tumors. The ethylene glycol molecules stop white
blood cells from recognizing the nanoparticles as foreign materials, allowing
them to circulate in the blood stream long enough to attach to cancer tumors.
However researchers at the University of California, San Diego believe that they
can increase the time nanoparticles can circulate in the blood stream. They are
coating nanoparticles containing therapeutic drugs with
membranes from red blood cells
and have shown that these nanoparticles will circulate in a mouse's blood stream for
almost two days, instead of the few hours observed for nanoparticles using
ethylene glycol molecules.
Researchers are also continuing to look for more effective methods to target
nanoparticles carrying therapeutic drugs
directly to diseased cells. For example scientists are MIT have demonstrated increased
levels of drugs delivery to tumors by using two types of nanoparticles. The
first type of nanoparticle locates the cancer tumor and the second type of
nanoparticle (carrying the therapeutic drugs) homes in on a signal generated by
the first type of nanoparticle.
Researchers at University College London are testing the
use of DNA to construct
pores in which drug molecules can be carried. The
researchers think this technique may allow more precise
delivery of drug molecules to diseased cells.
Researchers at Oregon State University are developing
nanoparticles that deliver three anti-cancer drugs
to the lymp nodes. The intent is to target cancers that
use the lymp nodes to spread through the body. Testing
of this technique, so far, has been with lab animals.
Researchers at the Institute of Bioengineering and Nanotechnology
and IBM researchers have demonstrated
sustained drug delivery
using a hydrogel. The hydrogel is injected under the skin, allowing
continuous drug release for weeks, with only one injection, rather than
repeated injections. They demonstrated this method by injecting the
hydrogel, containing the chemotherapy drug herceptin, under the skin of
laboratory mice. The study showed significant reduction in tumor size.
Other researchers are using a
to enhance the ability of drug carrying nanoparticles to enter
tumors. First they let the photosensitizing agent accumulate in the
tumor, then illuminate the tumor with infrared light. The
photosensitizing agent causes the blood vessels in the tumor to be more
porous, therefore more drug carrying nanoparticles can enter the tumor.
Two researcher groups have been focused on the best shape of nanoparticle to use for
delivering drugs to cancer tumors. One research group has found that a disk shaped
will stick to the surface of a tumor longer than a spherical shaped nanoparticle,
providing more efficient transfer of therapeutic drugs to the tumor.
Another set of researchers have found that
nanoparticles are more effective at delivering chemotherapy drugs to
breast cancer cells than spherical nanoparticles.
Using gold nanoparticles to deliver platinum to cancer tumors may reduce the
side effects of platinum cancer therapy. The key is that the toxicity level of
platinum depends upon the molecule it is bonded to (for the tech types the
toxicity depends upon the oxidation state of the platinum). So the researchers
chose a platinum containing molecule that has low toxicity to attach to the gold
nanoparticles. When the platinum bearing nanoparticle reaches a cancer tumor it
encounters an acidic solution which changes the platinum to it's toxic state, in
which it can kill cancer cells. For more details read the article at this
Using nanoparticles to deliver nitric oxide directly to cancer cells may reduce the
required amount of chemotherapy drugs. Researchers conducting tests on neuroblastoma cancer
cells found that the effectiveness of the chemotherapy drug was increased 5
nanoparticles were used to deliver nitric oxide directly to the cancer
Other researchers are taking a different approach to delivering platinum to
cancer tumors. Instead of attaching platinum to nanoparticles they have used
molecular building blocks to produce nanoparticles designed to deliver platinum
to cancer tumors. For more details read the article at this
A method being developed to fight skin cancer uses gold nanoparticles to
which RNA molecules are attached. The nanoparticles are in an ointment
that is applied to the skin. The nanoparticles penetrate the skin and
the RNA attaches to a
cancer related gene, stopping the gene from generating proteins that
are used in the growth of skin cancer tumors.
Reseachers have developed elastic materials
embedded with needle like carbon nanofibers. The material is
intended to be used as balloons which are inserted next diseased
tissue, and then inflated. When the balloon is inflated the
carbon nanofibers penetrate diseased cells and delivery
More info on the use of
Nanotechnology in Cancer
Nanotechnology in Drug Delivery - Heart Disease:
Researchers at Clemson University have developed a nanoparticle that
uses a protein to
attach to damaged regions of arteries. This allows drugs to be
applied directly to the damaged portion of the artery.
Lab studies in mice have shown that using nanoparticles to target the
delivery of the clot busting drug tPA can reduce the dosage of tPA
needed, which may reduce possible side affects, such as internal
bleeding. The clot busting drug was attached to a cluster of
nanoparticles that break apart
in regions of turbulent blood flow, like that found when a blood
flow is restricted by a clot.
Researchers are developing polymer nanoparticles that home in on
such as arterial plaque and dissolve, releasing drugs, in the presence of
hydrogen peroxide that is present in the inflamed tissue.
Nanoparticles containing iron oxide that allows the nanoparticles to
directed, by a magnetic field, to stents. This could allow drugs to
be delivered directly to stents placed in arteries.
More info on applications of
Nanotechnology to Heart
Nanotechnology in Drug Delivery - Aging and other areas
Drugs to treat glaucoma is being attached to
nanodiamonds which are embedded in
contact lenses. The drug molecules are released from the
nanodiamonds are in contact with tears, providing a more consistent
dosing than often occurs using eye drops.
Researchers are improving dental implants by
nanotubes to the surface of the implant material. They have
demonstrated to the ability to load the nanotubes with anti-inflammatory
drugs that can be applied directly to the area around the implant. As
well they have shown that bone adheres better to titanium dioxide
nanotubes than to the surface of standard titanium implants.
Researchers have developed
nanoparticles that release insulin when glucose levels rise. The
nanoparticles contain both insulin and an enzyme that dissolve in high
levels of glucose. When the enzyme dissolves the insulin is released. In
lab test these nanoparticles were able to control blood sugar levels for
Another method being developed to release insulin uses a
sponge-like matrix that
contains insulin as well as nanocapsules containing an enzyme. When
the glucose level rises the nanocapsules release hydrogen ions, which
bind to the fibers making up the matrix. The hydrogen ions make the
fibers positively charged, repelling each other and creating openings in
the matrix through which insulin is released.
A method being developed to tackle autoimmune diseases uses
nanoparticles to deliver antigens for a particular disease into the
blood stream. The
antigens reset the immune system, stopping white blood cells from
attacking healthy cells. This method has been tested in the lab on mice
with a disease similar to multiple sclerosis with promising results.
Researchers are developing nanoparticles that can delivery drugs across the
to tackle neurologic disorders.
A method being developed to
fight aging uses mesoporous nanoparticles
with a coating that releases the contents of the nanoparticle when an
emzyme found in aging cells is present.
Skin creams that uses
from stem cells to prevent aging of the skin. These proteins are
encapsulated in liposome nanoparticles which merge with the membranes of
skin cells to allow delivery of the proteins.
Researchers have developed a nanoparticle that can slip through mucus coating
surfaces such as lung tissue. This ability to penetrate the mucus coating should
provide the capability to
coat lung tissue with therapeutic drugs.
Medical implants made of porous plastic, coated with carbon nanotubes.
Therapeutic drugs, which are attached to the nanotubes can be released into the
bloodstream, for example, when a change in the blood chemistry signals a
problem. NASA is developing these implants, called a "biocapsule",
to protect astronauts from the effects of radiation however the implants may
also be useful for releasing insulin for diabetes patients or for delivering
chemotherapy drugs directly to tumors.
Earl Boysen of Hawk's Perch Technical Writing, LLC and
UnderstandingNano.com. You can find him on