Expanding the biomedical potential of boron nitride

Thermal stability, chemical inertness, and electrical insulation properties make hexagonal phase boron nitride (h-BN), a layered crystal structurally similar to graphite, ideal for biomedical applications. The material can also be exfoliated into boron nitride nanosheets (BNNSs) and can be downsized into several nanometers to form boron nitride quantum dots (BN QDs).

BN QDs, however, usually emit a range of visible fluorescence indicative of impurities and defects that, while unrelated to the quantum confinement effect, render them impractical for biomedical applications.

In a review, Yap et al. demonstrated how to make a new form of BN nanoparticles, known as BN dots, that do not have inherent fluorescence and maintain the electrically insulating nature of BNNSs. The authors integrated each BN dot with tens of organic dye molecules and one single-stranded deoxyribonucleic acid or oligonucleotide to form high-brightness probes (HBPs).

“We leverage BN dots’ insulating nature to retain the quantum yield of the conjugated organic dye molecules,” said author Yoke Khin Yap. “This novel method allows us to scale fluorescence intensity more than 10 times higher than single organic dye molecules to create high-brightness fluorophores (HBFs).”

The authors used HBPs to stain a specific gene sequence and could then detect signals without electron-multiplying charged-coupled detectors. In contrast, they barely observed mRNA fluorescence using benchmark commercial probes.

“HBPs are great for intracellular detection and will enable the detection of rare genetic sequences,” said Yap.

Source: “Boron nitride nanosheets, quantum dots, and dots: Synthesis, properties, and biomedical applications,” by Raksha Dubey, Matthew Cowles, Zohreh Salimi, Xiuling Liu, Rodney Oakley, Nazmiye Yapici, Join Uddin, Dongyan Zhang, Yoke Khin Yap, APL Materials (2025). The article can be accessed at https://doi.org/10.1063/5.0255590 .