Gold and Graphene: New Allies in Medicine

In a study published in Science Advances, scientists discovered how to control the beating of human heart cells in a dish using only light and graphene. Now, all potential drugs will be tested on heart cells to ensure that, for example, pain medication does not cause a heart attack. These cardiac cells in question are grown in glass or plastic dishes. But glass and plastic don't conduct electricity, and our hearts do - which means that the tests are not as realistic as they could be.

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Graphene, however, converts light into electricity and is also non-toxic. In this study, scientists learned to precisely control the amount of electricity that graphene generates by changing the amount of light they emit in the material. When they developed cardiac cells in graphene, they were able to manipulate the cells too, says study co-author Alex Savtchenko, a physicist at the University of California, San Diego. They could make it 1.5 times faster, three times faster, 10 times faster, or as much as they needed.

This means that scientists can cause graphene to mimic an electricity pattern similar to various heart diseases, which makes it easier to test heart medications and other new drugs. Later, Savtchenko hopes that this method can be used to build a better pacemaker, as they control the heartbeat and are usually made of electrodes that can cause internal scarring. Instead of electrodes, Savtchenko imagines, we could have a small piece of long-lasting graphene attached to a heart muscle. (graphene would be controlled by a tiny light source implanted nearby and would not cause scarring). Even further, graphene could be used to control electricity in the brain and help treat neurodegenerative diseases like Parkinson's. "The human heart is fantastically resistant, but it is still just a bomb," he says. There is much more that can be done.

Another material with a lot of potential in medicine is gold. Gold nanoparticles are safe for the body and chemically stable. These nanoparticles can be coated with a specific drug and are so small that they can move easily through the body and go straight to where the drug is needed.

That's the idea, but when you inject a gold nanoparticle into the body, it is immediately covered by proteins that are already in the blood, called whey proteins, says Enrico Ferrari, a nanotechnologist at Lincoln University. Serum proteins alert the immune system, which will attack the particle in the same way that it fights all other body invaders. Our bodies want to prevent the particle from reaching its source, according to Ferrari, and if successful, the drug will degrade and end up in the spleen, rather than where it should go.

Then Ferrari developed a new way to make nanoparticles and their results were recently published in Nature Communications. He added a layer of protein that prevents the serum protein from attacking. Think of this new layer as an adapter, says Ferrari. One side binds well to gold and keeps whey proteins at bay. The other side is designed to make it easier to find the specific target in the body that the drug needs to reach. In theory, this new method can be tried with any type of drug and gold nanoparticles, and Ferrari wants to work with other scientists to take this beyond the laboratory.

Gold nanoparticles can also be used to monitor cancer, says Matt Trau, a chemist at the University of Queensland (Trau is the author of a different study, also recently published in the journal Nature Communications). Cancer tumors usually release small cells that circulate through the blood. The cells, called circulating tumor cells (CTCs), are quite different from each other and can create more tumors, so it is important to keep an eye on them. There are some clues as to where CTCs maybe - these cells usually have a particular type of protein - but they are still very difficult to detect. Imagine trying to catch 10 criminals across New York City, says Trau.

When "criminals" are cancer cells, you need to make sure you are right, because if you don't, you will make the wrong treatment decision.

Trau and his team designed several gold nanoparticles so that they could track one of four different types of CTCs. "You prepare all the particles, mix them up and throw the particles into the blood sample," he says.  Essentially, these nanoparticles are trained to search for and attach to the specific type of protein that marks a CTC. When you make a fluorescent line on the particles, they emit a unique bar code. If the nanoparticle finds and sticks to the protein's target, the barcode changes so you know which CTC it found and how many. Different particles are designed to find different CTCs.

For the study, Trau tested the new technique on blood samples that were taken from patients with melanoma who had died before, during, and after treatment. The nanoparticles showed the different types of tumor cells in each sample, how the immune system was reacting, and whether there were any side effects. Now, his team wants to use this method to examine more blood samples and other types of CTCs.

Although they only looked at four this time, they could easily look for much more. And they want to test it in real-time. "If only we had seen this in real-time, we could have made decisions about changing the patient's dose," he says. "These are insights into cancer that we haven't seen before."

Source: Angela Chen for The Verge