New Two-Dimensional Material Paves Way for Safer, More Effective Implantable Medical Devices

Borophene, first synthesized in 2015, is an atomically thin version of boron that surpasses graphene—the two-dimensional (2D) version of carbon—in conductivity, thinness, lightness, strength, and flexibility. Borophene is a fascinating material as it closely resembles carbon, including its atomic weight and electron structure, yet it exhibits even more remarkable properties. Currently, researchers are just beginning to tap into its potential uses. One of the key features of borophene is its structural polymorphism, allowing its boron atoms to be arranged in various configurations, much like constructing different objects from the same set of Lego blocks. This versatility enables researchers to "tune" borophene’s properties according to specific needs. Now, in the first-ever study to understand the biological interactions of borophene, researchers have improved this material in the lab by imparting chirality to this atomically thin version of boron.

Chirality in molecules is similar to the difference between left and right hands—similar, yet not interchangeable, as a left mitten does not fit the right hand as well as it fits the left. Researchers at Penn State (University Park, PA, USA) have discovered that various polymorphic structures of borophene interact distinctly with biological cells, with their paths of cellular internalization uniquely determined by their structures. The researchers created borophene platelets, similar to blood cellular fragments, through solution state synthesis. This process involves combining powdered boron in a liquid with external factors like heat or pressure until the desired structure forms.

Image: The researchers tweaked borophene to interact with cells and other biological units in unique ways (Photo courtesy of Dipanjan Pan/Penn State)

During their experiments, the researchers subjected boron powders to high-energy sound waves, then mixed the resultant platelets with different amino acids in a liquid to impart chirality. They observed a preference for sulfur atoms in the amino acids to attach to the borophene over the nitrogen atoms. Notably, certain amino acids, such as cysteine, would bind to specific sites on the borophene, influenced by their chiral handedness. When these chiralized borophene platelets were introduced to mammalian cells in a laboratory dish, the researchers noted that the platelets' handedness altered their interactions with cell membranes and their method of entering the cells. This insight could lead to applications like enhanced medical imaging for more precise tracking of cell interactions, or improved drug delivery systems that target material-cell interactions more accurately. Ultimately, a deeper understanding and control of how borophene interacts with cells may pave the way for the development of safer and more effective implantable medical devices.

“To the best of our knowledge, this is the first study to understand the biological interactions of borophene and the first report of imparting chirality on borophene structures. Borophene’s unique structure allows for effective magnetic and electronic control,” said Dipanjan Pan, who led the team, noting the material could have additional applications in health care, sustainable energy and more. “This study was just the beginning. We have several projects underway to develop biosensors, drug delivery systems and imaging applications for borophene.”

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