by Angela Chen: Scientists can control heart cells using just graphene and light…
Graphene and gold could lead the way to better health by helping us test new drugs, deliver drugs more accurately, and even monitor cancer.
In one study published today in the journal Science Advances, scientists figured out how to control the beating of human heart cells in a dish using just light and graphene. Right now, all potential drugs are tested on heart cells to make sure that, say, pain medication won’t give you a heart attack. These heart cells in question are grown on glass or plastic dishes. But glass and plastic don’t conduct electricity, and our hearts do — which means that the tests aren’t as realistic as they could be.
Graphene, however, converts light into electricity and it’s not toxic either. In today’s study, scientists learned to precisely control the amount of electricity graphene generates by changing how much light they shine on the material. When they grew heart cells on the graphene, they could manipulate the cells too, says study co-author Alex Savtchenko, a physicist at the University of California, San Diego. They could make it beat 1.5 times faster, three times faster, 10 times faster, or whatever they needed.
This means scientists can make the graphene imitate a pattern of electricity similar to various heart diseases, which makes it easier to test heart medications and other new drugs. Later on, Savtchenko hopes this method can be used to build a better pacemaker. Pacemakers control the beating of the heart and are usually made from electrodes that can cause internal scarring. Instead of electrodes, Savtchenko imagines, we could have a small, long-lasting piece of graphene attached to a heart muscle. (The graphene would be controlled by a tiny light source implanted nearby and wouldn’t cause scarring.) Even further on, graphene could be used to control the electricity in the brain and help treat neurodegenerative diseases like Parkinson’s. “The human heart is fantastically resilient, but it’s still just a pump,” he says. There’s a lot 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 they’re so small that they can move through the body easily 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 already in the blood called serum proteins, says Enrico Ferrari, a nanotechnologist at the University of Lincoln. The serum proteins alert the body’s immune system, which will attack the particle in the same way it fights all other bodily invaders. Our bodies want to keep the particle from getting to its source, according to Ferrari, and if it succeeds, the drug will degrade and end up in the spleen instead of where it was supposed to go.
So Ferrari developed a new way of making nanoparticles and his results were recently published in Nature Communications. He added a layer of proteins that prevents the serum protein from attacking. Think of this new layer like an adapter, says Ferrari. One side binds very well to the gold and keeps the serum proteins at bay. The other side is engineered so it can more easily 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 nanoparticle, and Ferrari wants to work with other scientists to bring this beyond the lab.
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 often shed tiny cells that circulate through the blood. The cells, called circulating tumor cells (CTCs), are all fairly different from each other and can create more tumors, so it’s important to keep an eye on them. There are some clues as to where the CTCs might be — these cells often have a lot of a particular type of protein — but they’re still very hard to catch. Imagine trying to catch 10 criminals in all of New York City, says Trau. When the “criminals” are cancer cells, you have to make sure you get it right because if you don’t, you’ll make the wrong decision about treatment.
Trau and his team engineered various gold nanoparticles so that they could track one of four different types of CTCs. “You prepare all the particles, you mix them together, and you throw the particles into the blood sample,” he says. Essentially, these nanoparticles are trained to seek out and attach to the specific type of protein that marks a CTC. When you shine a fluorescent line on the particles, they emit a unique “barcode.” If the nanoparticle finds and attaches to the protein target, the barcode changes so you know which CTC it found and how many. Different particles are engineered to find different CTCs.
For the study, Trau tested the new technique on samples of blood that were taken from already deceased melanoma patients before, during, and after treatment. The nanoparticles showed the different types of tumor cells in every sample, how the immune system was reacting, and whether there were side effects. Now, his team wants to use this method to look at more blood samples and other types of CTCs. Though they only looked at four this time, they could easily look for many more. And they want to trial this in real time. “If only we saw this in real time, we could have made decisions about changing the patient dose,” he says. “These are insights into cancer that we haven’t seen before.”