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.
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 (HKU) revealed for the first time the inhibitory effect on oral pathogenic biofilms by high-pressure high-temperature (HPHT) 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.
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 sixth 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.
“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.
This knowledge and impact of NDs can also be translated to prevent other life-threatening infections in the body, in particular as antifungal drugs, for those vulnerable to fungal infections including very old and very young people, and those who are immunocompromised due to diseases such as HIV infections and diabetes, chronic users of steroids, and cancer patients undergoing chemotherapy. Since fungal cells are very similar to human cells, developing antifungal agents that are not harmful to humans has always been a major challenge.
Please
click here for the journal paper published in Biomaterial Science, Issue 15, 2021.
For media enquiries:
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Tel: 3917 8519
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Ms Melody Tang, Senior Communications Officer
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口腔疾病如蛀牙、牙周病和真菌感染等是全球關注的公共衞生議題，每年相關的醫療開支龐大。這些口腔疾病的成因，主要是致病細菌或真菌附著牙齒表面並形成生物膜群落。美國國家衞生院的數據顯示，65 - 80%的人類口腔感染是由生物膜導致。
香港大學（港大）工程學院和牙醫學院合作的研究團隊，首次揭示納米鑽石對口腔致病生物膜有抑制作用，並有效對抗口腔内浮游的細菌等微生物病原體，具潛力發展為新一代抗菌劑，為纏繞人類已久的口腔健康問題，提供有效的解決方案。研究結果已於學術期刊《Biomaterials Science》刊登，題為「納米鑽石對口腔致病生物膜的抑制作用」。
蛀牙是人類最常見的疾病之一，影響著全球近半（48%）超過30億人口，主要是口腔内產生酸性的細菌在牙齒表面形成一層生物膜所引致，變異鏈球菌（Streptococcus mutans）被認為是發病的關鍵。牙周病是人類第六大流行疾病，全球患病率為11.2%，主要由牙齦卟琳單胞菌（Porphyromonas gingivalis）誘發。而口腔内的微生物失調，與肥胖、阿爾茨海默氏症和心血管疾病等全身系統疾病均有關連。這些病原體一直對抗生素存有高抗藥性，目前未有徹底的解決方法。另一種對身體可能構成嚴重影響的口腔疾病是真菌感染，而針對抑制真菌滋長的研究，過去十多年並沒有多大進展。
今次研究由電機電子工程系助理教授褚智勤博士，以及牙髓病學臨床助理教授聶燊朗醫生共同擔任首席研究員。他們發現，經高壓高溫處理的納米鑽石，對幾種預選的口腔病原體，包括真菌（白色念珠菌和光滑念珠菌）和細菌（變異鏈球菌和牙齦卟琳單胞菌）的生物膜形成，有明顯的抑制作用，對消除經已形成的生物膜也具有一定作用。
「納米物料是當前物料科學的熱門課題。這些超小粒子能滲透入微生物當中，又可利用作廣泛的藥物輸送。我們的研究説明了這些納米粒子能操控病原體内的遺傳機制，防止它們附著在任何物質的表面，因而對生物膜的形成有抑制作用。」褚智勤博士和聶燊朗醫生解釋説。
「鑽石具有彈性表面和優異的生物相容性的特性，而納米鑽石已證實對人體無害。我們的實驗成果不單有助理解納米鑽石和口腔病原體的關係，更展示了納米鑽石應用於臨床抗菌治療的巨大潛力，讓相關的臨床應用研究得以加快開展。」褚智勤博士和聶燊朗醫生補充説。
他們表示，研究成果可延伸應用於對付其他的感染，尤其是真菌感染。幼童和長者，愛滋病和糖尿病患者，以及需長期服用類固醇或進行癌症化療的病人的免疫力較低，容易受真菌感染，而由於真菌細胞與人體細胞非常相似，研發對人體無害的抗真菌劑一直是科學家的重大的挑戰。
刊登於Biomaterial Science, 2021 年第15期的論文「納米鑽石對口腔致病生物膜的抑制作用」
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