Nanotechnology Exploring the World of Nano Medical Devices

Offering the possibilities of smaller, lighter, and faster materials and devices, nanotechnology is working its way into the world of medical technology. Nanotechnology is in its infancy, and no one can predict with accuracy what will result from the full flowering of the field over the next several decades. Many scientists believe it can be said with confidence, however, that nanotechnology will have a major impact on medicine and health care; energy production and conservation; environmental cleanup and protection; electronics, computers, and sensors; and world security and defense. - Mohammed Ahmeduddin, Avinash Venkat Raman

What is Nanotechnology?

Nanotechnology is the creation and use of materials or devices at extremely small scales. Scientists refer to the dimensional range of 1 to 100 nm as the nanoscale, and materials at this scale are called nanocrystals or nanomaterials. One nanometer is a magical point on the dimensional scale. It is the length of a small molecule.

Nanotechnology involves basic research on structures having at least one dimension of about one to several hundred nanometers; it is the application of nanoscience in technological devices; whereas Nanoscience is discipline involving scientific understanding and investigation of nanoscale phenomena.

The concept of nanotechnology originated with American physicist Richard P. Feynman. Feynman calculated that the entire content of Encyclopaedia Britannica could be reduced to fit on the head of a pin, and he estimated that all of printed human knowledge could be reduced to fit on 35 normal-sized pages. Human beings have actually known about these special properties for some time, although they did not understand why they occurred. Glassworkers in the Middle Ages, for example, knew that by breaking down gold into extremely small particles and sprinkling these fine particles into glass the gold would change in color from yellow to blue or green or red, depending on the size of the particle. These glassworkers did not realize it at the time, but they had created gold nanocrystals. At scales above 100 nm gold appears yellow, but at scales below 100 nm it exhibits other colors.

A number of important breakthroughs have already occurred in nanotechnology. These developments are found in products used throughout the world. Some examples are catalytic converters in automobiles that help remove air pollutants, devices in computers that read from and write to the hard disk, certain sunscreens and cosmetics that transparently block harmful radiation from the Sun, and special coatings for sports clothes and gear that help improve the gear and possibly enhance the athlete’s performance. Still, many scientists, engineers, and technologists believe they have only scratched the surface of nanotechnology’s potential.

Nanotechnology is expected to become the transformational technology of this century. Nanomaterials, have different and often amazing nanostructure-dependent properties (e.g., chemical, mechanical, electrical, biological, optical or magnetic), which make them desirable for medical applications.

Nanotechnology can offer solutions by means of smaller, lighter, faster, and better-performing materials, components, and systems. Nanomaterials are being used in computers, cosmetics, stain-resistant fabrics, sports equipment, paints, and medical diagnostic tests.

The Tools of Nanotechnology

The scientific community began serious work in nanoscience when tools became available in the late 1970s and early 1980s—first to probe and later to manipulate and control materials and systems at the nanoscale. These tools include the transmission electron microscope (TEM), the atomic force microscope (AFM), and the scanning tunneling microscope (STM).

Current and Future Developments in the Field of Health

More than 60 drugs and drug-delivery systems based on nanotechnology, and more than 90 medical devices or diagnostic tests are already being tested, clinical studies have begun to study an adaptive retinal implant designed to restore partial vision in cases of blindness caused by retinitis pigmentosa. The system includes a tiny camera in the frame of eyeglasses. The camera transmits images of the surroundings to a special adaptive signal processor.

Developments in nanoscale biomedicine should be able to create implants that release drugs on demand and monitor blood chemistry. A tiny jab in the finger will be enough for future blood analysis to measure cholesterol and glucose, and the results can be e-mailed to the nearest nanomedical center for a more accurate diagnosis and treatment.

Using nanotechnology, the medication could be carried in supramolecular hollow molecules, nanoscale transport containers with antennas to which antibodies of similar sensory proteins are attached. When the molecules come into contact with structures typical of the agent responsible for the illness, they dock onto it and send a signal to the hollow molecule, which opens up and releases its contents. With such nanotechnology, medications could be delivered in high doses directly to the source of the illness, placing no stress on the rest of the body and minimizing side effects.

In the United States, the National Cancer Institute has committed to a new five-year initiative to develop and apply nanotechnology to cancer. Nanotechnology supports and expands scientific advances in genomics and proteomics while it builds on our understanding of the molecular underpinning of cancer.

One of the first nanoscale devices to show promise in fighting cancer and administering drugs is a tiny construction called a nanoshell. A nanoshell consists of beads that are about three millionths of an inch wide, with an outer metal wall and an inner silicon core. By varying the size ratio between the wall and core, scientists can tune the shells precisely to absorb or scatter specific wavelengths of light. Gold-encased nanoshells can convert these specific wavelengths of light into heat. Selectively binding these shells to malignant cells could provide a means for fighting cancer.

A key focus of nanotechnology researchers is to develop new ways to seek out and destroy cancer cells. To avoid damage to normal tissue, the nanocapsule is coated with sensors that zero in only on tumor cells. A patient would then be exposed to low-dose radiation or drugs that trigger the gene to make the necrosis factor. Nanoparticles are also capable of passing through the blood-brain barrier filter system, so that they can be used as specially coated magnetite particles that are warmed by an alternating electromagnetic field to combat brain tumors.

According to a recent review, nanotechnology has three major uses in medicine. The first is delivering the exact dose of a drug to the intended location. The second is providing new ways to grow and repair body tissues; the third is using the detection of single molecules in diagnosis. All of this means that new discoveries will present many exciting challenges for regulatory affairs, clinical research, and research and development personnel.

Nanotechnology in Medicine (Nanomedicine)

Nanomedicine is the medical use of molecular-sized particles to deliver drugs, heat, light or other substances to specific cells in the human body. Engineering particles to be used in this way allows detection and/or treatment of diseases or injuries within the targeted cells, thereby minimizing the damage to healthy cells in the body.

Nanotechnology Characterization Laboratory

Eliminating suffering and death from cancer requires an unprecedented collaborative effort that leverages resources from government, industry, and academia. Working in concert with the National Institute of Standards and Technology (NIST) and the U.S.

Food and Drug Administration (FDA), the National Cancer Institute (NCI) established the Nanotechnology Characterization Laboratory to perform preclinical efficacy and toxicity testing of nanoparticles.

The NCL serves as a national resource and knowledge base for all cancer researchers to facilitate the regulatory review of nanotechnologies intended for cancer therapies and diagnostics.

Exploring Nanotechnology in Cancer

Nanotechnology offers the unprecedented and paradigm-changing opportunity to study and interact with normal and cancer cells in real time, at the molecular and cellular scales, and during the earliest stages of the cancer process. Through the concerted development of nanoscale devices or devices with nanoscale materials and components, the NCI Alliance for Nanotechnology in Cancer will facilitate their integration within the existing cancer research infrastructure.

The Alliance will bring enabling technologies for:

• Imaging agents and diagnostics that will allow clinicians to detect cancer in its earliest stages.
• Systems that will provide real-time assessments of therapeutic and surgical efficacy for accelerating clinical translation.
• Multifunctional, targeted devices capable of bypassing biological barriers to deliver multiple therapeutic agents directly to cancer cells and those tissues in the microenvironment that play a critical role in the growth and metastasis of cancer.
• Agents that can monitor predictive molecular changes and prevent precancerous cells from becoming malignant.
• Novel methods to manage the symptoms of cancer that adversely impact quality of life.
• Research tools that will enable rapid identification of new targets for clinical development and predict drug resistance.

Risks to Health and Challenges Confronting Nanotechnology

Although there are a number of promising breakthroughs in medicine, relatively little is known about the potential health and environmental effects of tiny particles. Laboratory studies, for example, have shown that inhaled airborne nanoscale materials depositing in the respiratory tract can cause an inflammatory response. The small size of engineered nanomaterials also makes their uptake easier into and between various cells, allowing for transport to sensitive target sites in the body, including bone marrow, spleen, heart, and brain.

There is a strong likelihood that biological activity of nanoparticles will depend on physiochemical parameters not routinely considered in toxicity screening studies. Because engineered nanomaterials show behavior that depends on their physical and chemical structure, risk assessment paradigms that have been developed based on traditional bulk chemistry alone may no longer be valid.

A major challenge facing nanotechnology is how to make a desired nanostructure and then integrate it into a fully functional system visible to the human eye. This requires creating an interface between structures built at the nanometer scale and structures built at the micrometer scale. But interfacing a nanocrystal with the outside world is a highly complex and expensive process.

Also, as the size of the nanostructure gets increasingly thinner, the surface area of the material increases dramatically, benefiting applications requiring a big surface area. But this large surface area tends to increase the possibility that other unwanted layers of molecules will adhere to the surface, harming the electrical performance of the nanotube devices.

Another important issue relates to the fact that the properties of nanocrystals are extremely sensitive to their size, composition, and surface properties. Any tiny change can result in dramatically different physical properties. Preventing such changes requires high precision in the development of nanostructure synthesis and fabrication.

Future Impact of Nanotechnology

Nanotechnology is expected to have a variety of economic, social, environmental, and national security impacts. It will play a major role relating to advances in health care technology and delivery system. In 2000 the National Science Foundation began working with the National Nanotechnology Initiative (NNI) to address nanotechnology’s possible impacts and to propose ways of minimizing any undesirable consequences.

The societal impacts from nanotechnology-based advances in human health care may also be large. A ten-year increase in human life expectancy in the United States due to nanotechnology advances would have a significant impact on Social Security and retirement plans. Nanotechnology can be expected to have national security uses that could both improve military forces and allow for better monitoring of peace and inspection agreements. Efforts to prevent the proliferation of nuclear weapons or to detect the existence of biological and chemical weapons, for example, could be improved with nanotech devices.

As in the fields of biotechnology and genomics, certain development paths in nanotechnology are likely to have ethical implications. Nanomaterials could also have adverse environmental impacts. Proper regulation should be in place to minimize any harmful effects. Because nanomaterials are invisible to the human eye, extra caution must be taken to avoid releasing these particles into the environment. Some preliminary studies point to possible carcinogenic (cancer-causing) properties of carbon nanotubes. Although these studies need to be confirmed, many scientists consider it prudent now to take measures to prevent any potential hazard that these nanostructures may pose.

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