Gold Nanoparticles 101

You may have heard of gold nanoparticles and not even realized it, since they’re also known as “colloidal gold” or sometimes “nano-gold.”

Tiny molecular particles of gold are suspended in a fluid (usually water) and if the gold particles are extremely small, the liquid appears to be an intense shade of red. If the particles are on the larger size, the liquid will be a dirty yellow color.

When gold is broken into nanoparticles it can break many different ways, depending on the process. Researchers have found particles in an assortment of shapes including rods, cubes, cap-shaped pieces, and spheres.

Nanotechnology is fairly new to our civilization, but it turns out that colloidal gold has been around since ancient times—and it was originally used to stain glass. It was rediscovered by Michael Faraday in the 1850s and almost immediately became one of science’s favorite substances.

Gold nanoparticles are highly useful for a wide range of processes including general nanotechnology, electronics manufacturing, and the synthesizing of rare materials.


In 2005 it was discovered that coating bacteria with nano-gold renders it extremely useful as a coating for electronic wiring. The bacteria carry a negative charge and the nano-gold carries a positive charge after being treated with nitric acid.

These coated bacteria are able to absorb water and conduct a more efficient electrical current after the gold has been introduced, making them more efficient and more cost-effective elements of electronic production.

Colloidal gold is also extremely useful in the medical field. Medical personnel are still investigating the possibilities for silver nanoparticles, but lab technicians have found that injecting gold nanoparticles into rats can relieve many symptoms of rheumatoid arthritis.

Similarly, they also found that if they implanted gold beads near arthritic joints in dogs, the gold beads acted as pain relievers and enabled the dogs’ joints to function almost normally. Since current arthritis medication is often woefully ineffective, this research is a big step forward–and as odd as it sounds, the day may soon come when general arthritis treatments will involve injecting gold particles into humans.

Gold nanoparticles may also provide the cure for Alzheimer’s. This terrible disease ravages the human brain with a buildup of plaque and betay-amyloid fibrils which affect our motor skills and memory functions, among others. Scientists have discovered that a combination of colloidal gold and microwave radiation can destroy these harmful plaques and fibrils, allowing the brain to heal itself and resume normal functions.

Investigations are also underway to determine whether conventional radiation therapy might not be improved and rendered less traumatic with the addition of nano-gold. But perhaps the most groundbreaking application of all lies in cancer treatment. Colloidal gold has been used in conjunction with intravenous spectroscopy to both identify and target malignant tumors in the human body.

The gold nanoparticles are introduced into the veins and guided by a spectroscope to locate problem tumors; they are then injected into the tumor along with an antibody to stop the tumor’s ability to grow and, in some cases, shrink its size.

In many cases medical scientists favor rod-shaped gold particles because they reflect infrared light more efficiently and their size allows them to circulate inside the bloodstream more easily. The shape of a gold nano-rod also lends itself well to the task of piercing a tumor’s mass.

The miraculous qualities of nano-gold were understood in a different way by the ancients, who devoted massive amounts of time and energy to alchemy and labeled a primitive form of colloidal gold the “Elixir of Life.” Many alchemists studied and searched their whole lives to find a means of creating a potion made from liquefied gold, believing that it would cure all sorts of bodily ailments and strengthen mental and physical capabilities.

There are many extant writings discussing the Elixir of Life, but it is not clear whether the formula was ever discovered. (However, a 16th-century alchemist named Paracelsus ultimately claimed that he had created the elusive potion.) Scientists knew that it could be done, since the ancient Romans had used colloidal gold in various concentrations to create stained glass.

The Romans found that they could get several colors out of the same gold particles simply by adding water and diluting the potion. They achieved stunning shades of yellow, red, and even mauve through this method.

Modern medicine considers gold nanoparticles capable of creating works of art in many other ways. Using nano-gold’s incredible ability to detect the exact location of cancer cells, researchers hope to have an effective cancer-fighting system in place by 2011.

They anticipate using microscopic nano-gold vessels to carry antidotes to the exact location of the cancerous growth, rather than inundating a patient’s sytem with high levels of toxic chemotherapy chemicals. Instead, it might be possible to target and kill the tumor on the spot by weakening it with gold nano-rods and then inject an ultimate cancer cure to kill off the dangerous cells completely.

The only remaining piece of the cancer-cure puzzle would then lie in finding such an ultimate cure for cancer itself, and scientists think they may have found that, too. The dye that is used to color your jeans and the ink in your ballpoint pen has the potential to team up with gold nanoparticles and kill cancer stone-dead.

This deep blue dye is pthalocyanine and it reacts with light in such a way that scientists can activate and deactivate them using simple, harmless light sources. Pthalocyanine is so responsive that they can even do this once the dye particles are deep inside your body at the location of a cancerous cell.

Up to this point, scientists were not sure how to get the dye inside a human body; every chemical vehicle they tried would predictably reject the dye cells.

But after extensive research, scientists have discovered that modified gold nanoparticles will transport pthalocyanine without any problems and, due to its cancer-seeking characteristics, the nano-gold actually plays an active part in the process. Strangely enough, you may find that a combination of blue jean dye and molecular gold will save your life someday.

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  1. #1 by twenneth on June 24th, 2011

    Understanding the adsorption of gold nanoparticles (AuNPs) on self-assembled monolayers (SAMs) is important because an assembly of the AuNPs-SAM-gold substrate provides easily controllable metal–metal junctions, in which fascinating phenomena such as electron tunneling and surface-enhanced Raman scattering can occur. In this work, we report strikingly different adsorption patterns of AuNPs on methyl-terminated SAMs. In contrast to the general belief that the terminal functional groups determine the surface properties of SAMs, the AuNPs adsorb on the surfaces of SAMs of 4-methylbenzenethiols (MBT) in a uniform, dispersed fashion, whereas aggregated adsorption is observed on the surfaces of SAMs of alkanethiols.

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