• Research
• Expressions Summer 2022

Diamond to Tackle Oral Infection

Dr Prasanna Neelakantan, Clinical Assistant Professor in Endodontics

Nanodiamonds as an Effective Agent to Inhibit Biofilm Formation

Diamonds are precious stones used for jewelleries and industrial purposes. But in the not-too-distant future, diamond nanoparticles, or nanodiamonds (NDs), may become the solution to everyone’s oral health.

Oral diseases such as dental caries (decay), gum diseases and fungal infections are major global health care problems, resulting in expenditures of millions of dollars every year and yet, have no established solutions. Complex microbial communities, typically occurring as disease-causing bacteria and fungi attaching to teeth surfaces and forming biofilm communities, are the main causes of infections. The National Institutes of Health states that 65-80% of all human infections are formed by biofilms.

NDs work as an effective agent against both free-floating cells (planktonic cells) and attached cells (biofilm) of bacteria and fungi that are highly relevant in oral and systemic infections

In a journal article published in Biomaterials Science titled “Biofilm inhibition in oral pathogens by nanodiamonds”, scientists from the Faculty of Engineering and the Faculty of Dentistry of the University of Hong Kong revealed for the first time the inhibitory effect on oral pathogenic biofilms by high-pressure high-temperature NDs.

Co-Principal Investigators of the study Dr Chu Zhiqin, Assistant Professor of the Department of Electrical and Electronic Engineering; and Dr Prasanna Neelakantan, Clinical Assistant Professor in Endodontics revealed that NDs work as an effective agent against both free-floating cells (planktonic cells) and attached cells (biofilm) of bacteria and fungi that are highly relevant in oral and systemic infections. In particular, they uncovered the role of NDs in inhibiting biofilm formation and their disrupting effect on preformed biofilms in several selected orally and systemically important organisms.

Our research showed that these ultra-small nanodiamonds can manipulate genetic mechanisms in the pathogens and prevent their attachment to any surface, hence inhibiting biofilm formation in the oral cavity

Dental caries is one of the most common diseases to affect humankind, affecting more than 3 billion people (48% of the population) worldwide. It is caused by a dominance of acid-producing bacteria that form biofilms on the surface of the teeth. Streptococcus mutans (S. mutans), a Gram-positive bacterium, is considered pivotal for the onset of this disease. Periodontal (gum) disease, which is the 6th most prevalent disease in humans with a global prevalence of 11.2%, is induced by Porphyromonas gingivalis (P. gingivalis), a Gram-negative bacterium. Notably, microbial dysbiosis in the oral cavity has been linked to systemic diseases such as obesity, Alzheimer’s and cardiovascular diseases. These microbials show high resistance to conventional antibiotics, and alternatives including nanotechnology are being intensively explored to provide more efficient therapeutics.

Moreover, fungal infections, another major oral disease with recognised clinical significance, have seen no advancement in the development of therapeutic drugs over the past several decades.

From left: Dr Prasanna Neelakantan and Dr Chu Zhiqin

“Nano-materials are the hot topic in current materials science as these ultra-small particles can effectively penetrate into microorganisms and can also be used to carry a wide variety of drugs. Our research showed that these ultra-small nanodiamonds can manipulate genetic mechanisms in the pathogens and prevent their attachment to any surface, hence inhibiting biofilm formation in the oral cavity,” explained Dr Chu and Dr Neelakantan.

“The results of this exciting study demonstrated the great potential of NDs as an alternative therapeutic platform to prevent and treat oral infections. NDs possess many promising features including excellent biocompatibility and flexible surface properties. They are also proven to be very safe for humans. Our work will promote a better mechanistic understanding of NDs on oral pathogens, paving the way for their clinical and translational applications,” they added.