[Image above] The hexagonal structure of borophene, illustrated above, has several polymorphs, which makes it easier to customize for specific applications, such as medical treatments. Credit: Borophene structure (Materialscientist, Wikimedia, CC BY-SA 3.0); Background (PickPik)
As the promise of nanotechnology starts to materialize in many industrial sectors, the medical field is making its way forward cautiously due to the many risks of tinkering with the delicate human machine. Despite these risks, researchers have made significant progress in this area, especially in terms of treating severe diseases such as cancer and difficult infections.
Graphene and its derivatives are at the forefront of these efforts due to their special physicochemical properties, which allow the materials to be easily functionalized by other nanoparticles or functional oxygenated groups. But in the past decade, other groups of nanomaterials started breaking into the medical world as well, including the emerging family of transition metal carbides and nitrides known as MXenes, which have featured frequently on CTT.
Borophene is one of the newest nanomaterials to begin making its way into biomedical applications. This material is very similar to graphene, consisting of boron rather than carbon atoms arranged in a hexagonal network. However, unlike graphene, borophene regularly forms in several different crystal structures (polymorphs), which allows for easier structural manipulation and thus customization of its material properties.
The ease with which researchers can manipulate the structure of borophene positions the material as a potential candidate for chirality. Chirality refers to the potential of a molecule to occur in two asymmetric forms that are nonsuperimposable mirror images of each. In other words, chiral molecules are like left and right hands: they can mirror each other precisely, but a left mitten will never fit the right hand as well as it fits the left hand.
Chirality is an important concept in drug design and development because chiral molecules can have different pharmacological activities and biological effects in the human body, despite having the same chemical formula. So, investigating the chirality of borophene molecules is vital to understanding how the material will interact with biological systems.
Borophene, though, is a highly reactive material that rapidly oxidizes in air. As such, developing a method to introduce chirality into the nanomaterial while preserving its stability is challenging.
In a recent paper, researchers at The Pennsylvania State University described a method based on liquid-phase probe sonication to produce chiral borophene nanoplatelets applicable to a variety of structural polymorphs. Using this methodology, they successfully produced chiral χ3 and β12 phases of borophene nanoplatelets via interaction with chiral amino acids.
Physicochemical characterization of the chiral borophene, along with exposure to mammalian cells, revealed the nanoplatelets have distinct interactions with the cellular membrane based on their chirality. For example, while β12 borophene primarily entered the cell through the energy-dependent and clathrin-independent endocytosis pathways, χ3 borophene entered the cell through the dynamin-mediated and clathrin-dependent endocytosis pathways.
This finding “demonstrated the potential for using such molecules in life science,” the researchers write.
In a Penn State press release, senior author Dipanjan Pan, Dorothy Foehr Huck & J. Lloyd Huck Chair Professor in Nanomedicine and professor of materials science and engineering and of nuclear engineering, says this study was just the beginning of their studies on borophene.
“We have several projects underway to develop biosensors, drug delivery systems, and imaging applications for borophene,” he says.
The paper, published in ACS Nano, is “Chiral induction in 2D borophene nanoplatelets through stereoselective boron–sulfur conjugation” (DOI: 10.1021/acsnano.4c01792).
