What Is a Gold Nanoparticle?

A gold nanoparticle, also known as colloidal gold, is a sub-micrometer particle created from gold. These nanoparticles, usually spherical or rod-like in shape, can be used in the medical and electron microscopy fields either to help detect or destroy cancer, or to help in labeling with microscopy experiments. To create a gold nanoparticle, gold ions are turned into neutral atoms, and citrate ions are added into the mixture. Gold nanoparticles are most commonly formed in a liquid solution and can be easily detected with a laser. Unlike the lustrous color of gold, the nanoparticles are deep red.

The synthesis of a gold nanoparticle solution can be done in many ways, but the most common starts with a gold ion that has a positive charge of three. After having the extra charge removed, it is added to a liquid solution, and citrate ions also are added to separate the gold into the nanoparticles. The scientist will know the gold is separated when it becomes a deep red color. If the atoms are not nanoparticles, but slightly larger, then the solution will appear as a murky yellow.

In the field of detecting cancer and electron microscopy, the gold nanoparticle solution is of great importance. When done without the nanoparticles, searching an area blindly can be difficult, and the observer may miss an object for which he or she is looking. If gold nanoparticles are added to the area, it will create a stain of sorts, from which light can bounce. By reflecting light, it makes it easier for observers to find cancer cells or to label other parts by attaching the gold to an antibody or lectin. This also is cheaper than using fluorescent dyes to find cancer and tends to be more effective.

Aside from helping medical experts find cancer, the gold nanoparticle solution also is useful in curing cancer. If the cancer is in an area where a laser can penetrate, the gold helps increase the laser’s effectiveness in destroying cancer cells. If a laser cannot penetrate the area, injecting gold nanoparticles into the cancer nucleus has been shown to stop cancer from reproducing and eventually kills it.

Another use of gold nanoparticles in the medical industry is as a drug carrier. Some medications receive interference from the mononuclear phagocyte system, a part of the immune system. Each gold nanoparticle is so tiny that they can commonly get around this system and deliver the medication to the body.