[attachment=11060]
Gold Nanotechnology in Medicine
Abstract
Nanomaterials are at the leading edge of the rapidly developing field of nanotechnology. Their unique size-dependent properties make these materials superior and indispensable in many areas of human activity.
The current work is on how nanomaterials make themselves useful in the field of medicine and surgery, with particular emphasis laid on those made of gold.
1) Aims/Objectives of the paper
 Analyze broadly, all the applications of nanotechnology in day-to-day life
 Analyze specifically, the applications of nanotechnology in the field of medical science
 Analyze the dangerous side-effects of the current cancer treatment methods like chemotherapy, bone-marrow transplantation, etc. on human body
 Study how nanotechnological ways of treating can are far more safe
 Analyze how gold nanotechnology is the safest compared to other nanotechnological methods, to treat cancer
2) Introduction to nanotechnology
Nanotechnology may be defined as the engineering of functional systems at the molecular scale. Generally it deals with structures sized between 1 and 100nm.
Nanotechnology may be able to create many new materials and devices with a vast range of applications, such as in medicine, electronics, biomaterials and energy production. On the other hand, nanotechnology raises many of the same issues as any new technology, including concerns about the toxicity and environmental impact of nanomaterials and their potential effects on global economics, as well as speculation about various doomsday scenarios. These concerns have led to a debate among advocacy groups and governments on whether special regulation of nanotechnology is warranted.
The first use of the concepts found in 'nano-technology' was in "There's Plenty of Room at the Bottom", a talk given by physicist Richard Feynman at an American Physical Society meeting at California Institute of Technology on December 29, 1959.
In the 1980s the basic idea of this definition was explored in much more depth by Dr. K. Eric Drexler, who promoted the technological significance of nano-scale phenomena and devices through speeches and the books Engines of Creation: The Coming Era of Nanotechnology (1986) and Nanosystems: Molecular Machinery, Manufacturing, and Computation, and so the term acquired its current sense.
There are two approaches in nanotechnology
 Bottom-up approach- materials and devices are built from molecular components which assemble themselves chemically by principles of molecular recognition.
 Top-down approach- nano objects are constructed from larger entities without atomic-level control.
3) Applications
a) Chemistry and environment: In these fields, nanotechnology finds a lot of applications in catalysis (due to very large values of surface to volume ratios) and filtration (nano porous membranes of very small pore size 10nm).
b) Energy: Through nanotechnology, reduction of energy consumption is often possible. It can also improve combustion in IC engines using specific catalysts with maximized surface area.
c) Communication and information: In the modern communication technology traditional analog electrical devices are increasingly replaced by optical or optoelectronic devices due to their enormous bandwidth and capacity, respectively. Two promising examples are photonic crystals and quantum dots. The production of displays with very low power consumption can be accomplished through carbon nanotubes.
d) Heavy industries: Nanomaterials also find wide applications in aerospace and construction.
e) Medicine: The biological and medical research communities have exploited the unique properties of nanomaterials for various applications (e.g., contrast agents for cell imaging and therapeutics for treating cancer). Terms such as biomedical nanotechnology, nanobiotechnology, and nanomedicine are used to describe this hybrid field. Functionalities can be added to nanomaterials by interfacing them with biological molecules or structures.
The applications of nanomaterials in the medical field include diagnostics, drug delivery and tissue engineering.
4) Gold Nanotechnology in medicine
Synthesis of gold nanoparticles
a) Add 20 mL of 1.0 mM HAuCl4 to a 50 mL beaker or Erlenmeyer flask on a stirring hot plate. Add a magnetic stir bar and bring the solution to a rolling boil.
b) To the rapidly-stirred boiling solution, quickly add 2 mL of a 1% solution of trisodium citrate dihydrate, Na3C6H5O7.2H2O. The gold sol gradually forms as the citrate reduces the gold(III). Remove from heat when the solution has turned deep red or 10 minutes has elapsed.
c) The presence of a colloidal suspension can be detected by the reflection of a laser beam from the particles. Because a laser pointer emits polarized light, the pointer can be oriented such that the beam appears to disappear. When the beam from the laser is visible in one view, it is invisible in the view perpendicular to the first.
Medical field applications of nanoparticles
 Drug delivery: One application of nanotechnology in medicine currently being developed involves employing nanoparticles to deliver drugs, heat, light or other substances to specific types of cells (such as cancer cells). Particles are engineered so that they are attracted to diseased cells, which allow direct treatment of those cells. This technique reduces damage to healthy cells in the body and allows for earlier detection of disease.
 Therapy techniques: They may be used to trap free radicals generated during an allergic reaction and block the inflammation that results from an allergic reaction. Nanoparticles, when activated by x-rays that generate electrons that cause the destruction of cancer cells to which they have attached themselves. Nanoparticles may be used, when inhaled, to stimulate an immune response to fight respiratory viruses.
 Diagnostic and imaging techniques: Quantum Dots (qdots) may be used in the future for locating cancer tumors in patients and in the near term for performing diagnostic tests in samples.
Why gold ?
A large number of chemical substances, organic and inorganic, have been made into nano sizes and have been found to exhibit excellent properties, paving way to their usage in a commercial way.
Even in medical field, a lot of metals, metal complexes and organic compounds in nano form have been tested successfully. But, gold being one of the most non-toxic substance among other metals created absolutely no side-effects.
Gold nanoparticles have been used to demonstrate multiphoton absorption induced luminescence (MAIL), in which tissues or cells are fluorescently labeled using special stains that enable them to be studied. Gold nanoparticles can emit light so strongly that it is readily possible single nanoparticles at laser intensities lower than those commonly used for MAIL sub-100-fs pulses of 790nm of light.
Moreover, gold nanoparticles do not blink or burn-out, even after hours of observation.
In addition, the laser light used to visualize the particles is a wavelength that causes only minimal damage to most biological tissues. This technology could enable us tracking of a single molecule of a drug in a cell or other biological samples.
Treatment of cancer
Nanoparticles, during drug delivery have the advantages that, they are:
 large enough that they don’t pass through the body; and
 Small enough that they don’t accumulate in vital organs and create toxicity problems.
Bottom-up approach is used more frequently when gold nanoparticles are used as medicines. Most animal cells are 10-20nm in diameter. Nanoparticles smaller than 100nm can enter the cells and organelles where they could interact with DNA and proteins. This could assist with the detection of disease in very small cell or tissue samples.
Currently used methods for cancer detection are physical examination or imaging techniques. Early molecular changes may not be detected by these methods. Nanoparticles solve this problem as they are highly sensitive and detect changes in even small percent of cells.
Adverse effects of chemotherapy
Due to the fact that chemotherapeutic drugs cannot selectively kill only the cancer cells, it has the following adverse effects on the health of patients:
 Depression of the immune system, which can result in potentially fatal infections.
 Fatigue: The treatment can be physically exhausting for the patient.
 Tendency to bleed easily: Medications that kill rapidly dividing cells are likely to reduce the number of platelets in the blood, which results in bleeding.
 Hair loss results due to the very same reason.
 Cardio-toxicity and hepatotoxicity can happen in some patients.
Unlike chemotherapy, nanotechnology allows treatments that target only cancer cells without harming nearby healthy cells.
Nanotechnology also allows the creation of therapeutic drugs that have a controlled, time-release strategy for delivering toxins.
5) Conclusion
Toxicity has been observed even while using gold nanoparticles at high concentrations. Studies using 2nm core gold nanoparticles have shown that cationic particles are moderately toxic, anionic particles are quite non-toxic.
If these problems are taken into account seriously, gold nanotechnology may become one of the most widely used methods to treat cancer in future.