‘Better than graphene’ material development

This new material, borophene, was first synthesised in 2015 and boasts a range of properties that surpass those of graphene, including enhanced conductivity, reduced thickness, lighter weight, greater strength, and superior flexibility. Recently, researchers at Penn State have further expanded the potential applications of borophene by imparting chirality to it, opening new avenues for advanced sensors and implantable medical devices.

The team, led by Dipanjan Pan, Dorothy Foehr Huck & J. Lloyd Huck Chair Professor in Nanomedicine and Professor of Materials Science and Engineering and of Nuclear Engineering, achieved a breakthrough by inducing chirality in borophene through a novel method. This property allows borophene to interact uniquely with various biological entities such as cells and protein precursors.

Pan explained: “Borophene is a very interesting material, as it resembles carbon very closely including its atomic weight and electron structure but with more remarkable properties. Researchers are only starting to explore its applications. 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.”

Chirality, or handedness, refers to the property where molecules can exist in two forms that are mirror images of each other, much like left and right hands. This characteristic can significantly influence how molecules interact with biological systems, often determining the efficiency and outcome of these interactions.

The study revealed that the various polymorphic structures of borophene interact with cells in distinct ways, with cellular internalisation pathways being dictated by their structures. This finding underscores the material's potential for tailoring interactions at a cellular level, which is crucial for applications in medical devices and sensors.

Pan stated: “Our study, for the first time ever, showed that various polymorphic structures of borophene interact with cells differently and their cellular internalisation pathways are uniquely dictated by their structures.”

Borophene's polymorphism allows its boron atoms to be arranged in different configurations, resulting in diverse shapes and properties. This versatility enables researchers to ‘tune’ borophene to exhibit desired characteristics, including chirality.

The researchers synthesised borophene platelets using solution state synthesis, a process that involves exposing boron powder in a liquid to external factors like heat or pressure. By mixing these platelets with different amino acids, they successfully imparted chirality to the material. They discovered that certain amino acids, such as cysteine, preferred to bind to borophene at specific locations based on their chiral handedness.

Pan detailed the process: “We made the borophene by subjecting the boron powders to high-energy sound waves and then mixed these platelets with different amino acids in a liquid to impart the chirality. During this process, we noticed that the sulphur atoms in the amino acids preferred to stick to the borophene more than the amino acids’ nitrogen atoms did.”

Upon exposing chiralised borophene platelets to mammalian cells, the researchers observed changes in how the material interacted with cell membranes and entered cells, influenced by their chiral handedness.

The implications of these findings are far-reaching. Pan highlighted the potential for borophene in developing high-resolution medical imaging, precise drug delivery systems, and safer, more effective implantable medical devices. The material's unique structure allows for efficient magnetic and electronic control, suggesting additional applications in healthcare, sustainable energy, and beyond.

Pan concluded: “This study was just the beginning. We have several projects underway to develop biosensors, drug delivery systems and imaging applications for borophene.”