Nano-gold's penetrating methods revealed in MIT, Swiss study

Gold nanoparticles have been known for years to have cell-penetrating properties that make them excellent candidates for uses in drug delivery. But what makes them so special in the nanotech arena? A team of professors at MIT and in the Ecole Polytechnique de Lausanne in Switzerland may have found the answer.

Researchers discovered in 2008 that gold nanoparticles coated with a polymer could penetrate cell membranes without damaging the cell, carrying drugs or diagnostics tools into the cell's machinery. How the nanoparticles were able to accomplish this, though, was mostly a mystery. The American-Swiss team set out to pull back the veil using both computer simulations and experiments in the lab.

It turns out, as the team published in the journal Nano Letters, it's all about the surface-coating polymer and the size of the particle. The one-molecule-thick layer that surrounds the tiny gold particle fuses with the lipid on the surface of the cell membrane and becomes engulfed by the membrane if it is small enough. What's more--and an important part of the process--the particle closes the hole behind it like a water-tight seal, keeping the membrane intact and protecting the cell and its contents.

In fact, the gold itself has no effect on the penetrating ability, but it does give structure to the nanoparticle, and gold nanoparticles are an easily prepared model system, according to the researchers. They have other properties, too, including possible therapeutic effects such as an ability to capture X-rays to destroy cancer cells from within.

The study's finding may help the researchers in creating new, more selective coating materials to deliver drugs and other molecules into cells that would normally have no way of gaining entrance.

- here's the MIT release