Artificial hips, pacemakers and stents are made up of biocompatible metals such as platinum or titanium to lessen the risk of rejection by the human body. For the majority of patients, these devices do not result in adverse effects, and they function inside the body without problems. But sometimes, implanting these biomedical devices made of foreign materials can cause pain, inflammation and rejection.
Now, scientists are looking to nature to find materials for implants that are more biocompatible than existing ones. They may have found one in the skin of the common pencil squid.
Researchers at the University of California, Irvine recently discovered that a protein called reflectin found in the skin of the squid species Loliginidae exhibit properties that make it an excellent candidate as a biocompatible material for advanced medical devices and sensors.
They studied how reflectin enables the pencil squid to reflect light and change colors. They then used reflectin to make thin films on a silicon substrate and let the films make contact with palladium hydride electrodes. After studying the electrical properties of reflectin, they concluded that it transported protons just as effectively as existing artificial materials.
“Nature is really good at doing certain things that we sometimes find incredibly difficult,” he said. “Perhaps nature has already optimized reflectin to conduct protons, so we can learn from this protein and take advantage of natural design principles,” Alon Gorodetsky, Ph.D., assistant professor of chemical engineering and materials science at The Henry Samueli School of Engineering at UC Irvine, said in a statement.
Gorodetsky said that unlike current materials, a naturally-occuring protein like reflectin is less likely to be rejected by the body. Also, its softness and flexibility make it ideal for use in future medical devices. Since it is biodegradable, it can decompose after it has served its purpose, thereby limiting the risk for complications.
“We plan to use reflectin as a template for the development of improved ion- and proton-conducting materials,” Gorodetsky said, who led the study published recently in the journal Nature Chemistry. “We hope to evolve this protein for optimum functionality in specific devices – such as transistors used for interfacing with neural cells – similar to how proteins evolve for specific tasks in nature.”
Because it interacts with cells using positively charged particles – just like how living tissues do – then reflectin “may be able to bridge the communication divide between cells and biomedical implants,” according to Popular Science. In contrast, medical devices like pacemakers, nerve stimulators and retinal implants communicate using negatively charged particles.
Other researchers have been developing biocompatible, proton-conducting materials such as ceramic oxides, polymers, solid acids, and metal–organic frameworks. But these materials may not be ideal components for future biomedical implants. Instead, the “potential modularity, tunability and processability of protein-based materials” like reflectin trump these artificial materials, according to the researchers.
Another sea dweller, the cuttlefish – incidentally a relative of the squid – is also being studied by a group of scientists at Carnegie Mellon University for its unique properties. In particular, they found that the ink from cuttlefish have the potential to power ingestible sensors.
Reflectin and similar substances could eventually wind up in future sensors and medical devices. As biomedical technologies become more intimate, the need arises for more biocompatible materials that pose little to no risk to the body, but also get the job done in terms of diagnosing, monitoring, and treating conditions.