Researchers Develop At-Home Device for Diagnosing Gingivitis and Periodontitis Caused by Bacteria

Engineers at the University of Cincinnati have developed a new device that can warn consumers about early risks of tooth decay from diseases such as gingivitis and periodontitis.

Gingivitis, the earliest form of gum disease, is caused by bacteria. But not just any bacteria.

The problem for researchers was getting a device to single out the particular type responsible for the disease, said Andrew Steckl, an Ohio Eminent Scholar and distinguished research professor in UC’s College of Engineering and Applied Science.

“It’s been quite the challenge to get to the point where we can detect this toxin created by the bacteria responsible for gingivitis,” he said.

Steckl and UC Senior Research Associate Daewoo Han collaborated with Sancai Xie, a principal scientist at Procter & Gamble Co., and described their results in a paper published in the Royal Society of Chemistry journal Sensors and Diagnostics.

Steckl’s research team has been exploring biosensing for various applications. They studied stress hormones in sweat in collaboration with the Air Force Research Lab at Wright-Patterson Air Force Base. Now they are studying saliva.

“There are good reasons to use saliva,” he said. “It’s relatively plentiful and easy to obtain through noninvasive methods. And saliva has a lot of important elements that can act as indicators of your health.”

Bacteria from gingivitis can travel through the bloodstream, leading to cardiovascular disease and other serious health problems, Steckl said.

But saliva is a complicated biofluid, Han said.

“We wanted to target a biomarker in saliva. But saliva is hard to use,” said Han, the study’s lead author.

Researchers pretreated the sample using potato starch to remove a protein called amylase that could interfere with the test results. Their test uses antibodies that react to the endotoxins found in the bacteria.

Developing a sensor required precise selectivity and sensitivity, Steckl said.

“Daewoo worked very hard on many dead-ends before he had success,” Steckl said. “I tell my students that research is search, search and re-search until you find the answer.”

At-home health testing has been available for generations for uses such as detecting pregnancy. But the COVID-19 pandemic introduced a wide audience of consumers to the concept of monitoring their health with new technology.

The at-home testing industry is expected to generate $45 billion annually by 2031, according to Allied Market Research.

Steckl said he sees a lot of opportunity for new consumer products.

“Our results definitely show promise,” Steckl said. “Sometimes it comes easy. Most of the time you have to persevere.”

Reference:

Salivary endotoxin detection using combined mono/polyclonal antibody-based sandwich-type lateral flow immunoassay device. Daewoo Han, Sancai Xieb and Andrew J. Steckl. Send. Diagn. 2023. DOI: 10.1039/d3sd00158j. 

Abstract

A point-of-care/use lateral flow assay (LFA) is reported for the detection of P. gingivalis endotoxin, a major saliva biomarker for oral health. Two different approaches of sandwich LFA design using either the combination of mono- and polyclonal antibodies or polyclonal antibody only have been evaluated to detect P. gingivalis endotoxins, having a limit of detection of ∼22 ng mL−1 and 46.5 ng mL−1 for water- and saliva-based samples, respectively. The LFA also exhibits good selectivity to P. gingivalis endotoxin versus other endotoxins and proteins. Saliva pretreatment combining syringe filtration and potato starch successfully inhibits α-amylase activity and provides improved results on LFA devices.

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TU Dresden Researchers Develop Highly Innovative Solutions for the Detection of Viral Pathogens

The outbreak of the COVID pandemic in 2020 has once again shown how important reliable and rapid detection methods are to initiate effective measures to combat a pandemic. Scientists from the Chair of Materials Science and Nanotechnology at TU Dresden (TUD) have made considerable progress in the development of highly innovative solutions for the detection of viral pathogens in two studies they presented recently. The results of their work have now been published in the journals "ACS Applied Materials & Interfaces" and "Advanced Materials Interfaces".  

Customized, powerful and adaptable nanoelectronic sensors represent a promising approach to be ready to fight both current and future pandemics. These sensors not only enable conventional diagnosis in cases of suspected outbreaks, but also a continuous monitoring of ambient air in buses, trains, schools or healthcare facilities. This means that appropriate and immediate measures can be taken as soon viruses appear.

Since 2020, the Dresden scientists have been working intensively on the development of miniaturized sensors for the accurate and efficient detection of SARS-CoV-2 antigens. In addition to the TUD team led by Prof. Gianaurelio Cuniberti and Dr. Bergoi Ibarlucea, scientists from the European Molecular Biology Laboratory (EMBL) in Hamburg, the Leibniz Institute of Polymer Research (IPF) Dresden and the Pohang University of Science and Technology (POSTECH) in Korea were also involved in the two studies.

Sybodies: a revolution in biological recognition

The first study, published in the journal ACS Applied Materials & Interfaces, describes a groundbreaking innovative approach that significantly increases accuracy and speed of SARS-CoV-2 antigen detection. It involves inserting synthetic nanobodies, known as sybodies, into biosensors as receptors. "Sybodies represent a rapid, sustainable and ethically sound alternative that, unlike conventional antibodies, is developed and manufactured using non-animal methods," said Prof. Gianaurelio Cuniberti, who coordinated both studies with Dr. Bergoi Ibarlucea. "Another key advantage of using sybodies is their smaller size compared to antibodies, so biological recognition processes can take place much closer to the sensor surface, increasing signal strength and making the sensors much faster and more sensitive," he adds. Initial tests have been successfully conducted with silicon nanowire-based field-effect transistors modified with sybodies, demonstrating the great application potential of this approach.

Overcoming the loss of sensitivity in biological fluids

In another paper published in the journal Advanced Materials Interfaces, the team is looking at increasing the sensitivity of the sensors when they operate in biological fluids. Such samples have a complex molecular composition, which severely limits the sensor's detection range. To solve this problem, the scientists developed a special surface modification with a hydrogel based on the dielectric polymer polyethylene glycol. This allows measurements to be taken directly in saliva and other samples from patients, and eliminates the need for time-consuming and costly sample preparation steps.

References:

C. Zhang, A. Parichenko, W. Choi, S. Shin, L. A. Panes-Ruiz, D. Belyaev, T. F. Custódio, C. Löw, J.-S. Lee, B. Ibarlucea, G. Cuniberti, Sybodies as Novel Bioreceptors toward Field- Effect Transistor-Based Detection of SARS-CoV-2 Antigens. ACS Applied Materials and Interfaces 15, 40191 (2023). https://doi.org/10.1021/acsami.3c06073

A. Parichenko, W. Choi, S. Shin, M. Schlecht, R. Gutierrez, T. F. Akbar, C. Werner, J. Lee, B. Ibarlucea, and G. Cuniberti, Hydrogel-Gated Silicon Nanotransistors for SARS-CoV-2 Antigen Detection in Physiological Ionic Strength. Advanced Materials Interfaces (2023). https://doi.org/10.1002/admi.202300391

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Japan Researchers Advance Rapid Bacterial Testing Tech to Prevent Food Poisoning

A new technology that speeds up bacterial testing in food is showing promise to “revolutionize” the process of testing bacterial viability in food, according to Japan-based scientists who discovered the breakthrough in food safety. 

They have used tetrazolium salt (MTT) to reduce the time taken to measure the number of viable bacteria in food electrochemically from two days to approximately one hour, irrespective of the bacterial species.

The technique can reportedly verify food safety before shipment from factories and prevent food poisoning – a major breakthrough, they note. 

WHO states that food safety, nutrition and food security are inextricably linked, with an estimated 600 million people falling ill and 420,000 dying each year due to contaminated food consumption. 

Food safety and hygiene in the food industry is of paramount importance.

Dr. Hiroshi Shiigi, professor and research lead at the Department of Applied Chemistry, Osaka Metropolitan University states, “In this study, we focused on the electrochemical properties of tetrazolium salts and developed a simple method for evaluating viable bacterial counts as an indicator of hygiene control in food and pharmaceutical production sites.” 

The researchers flag that the technique can confirm the safety of food products before they leave the factory and prevent food poisoning.

“One of the most important assessment indicators for ensuring that food is free from contamination is the number of viable bacteria. However, conventional measurement methods take up to two days to yield results, and these results are only available after the food has been shipped from the factory—leading to potentially fatal consequences,” explains Dr. Shiigi.

“Therefore, it is imperative to have a testing method that speeds up the process of identifying bacterial contamination before shipment,” he adds.

According to Dr. Shiigi, the team will continue to optimize the measurement conditions and expect to see the “development of a portable sensor” in line with the development of research aimed at practical applications.

Notably, the method does not require complicated operations or expensive equipment. 

The scientist flags that MTT, a water-soluble molecule, has excellent cell membrane permeability and changes into insoluble reduced formazan inside the cell.

“The number of viable bacteria can be estimated by focusing on the reduction current of MTT remaining in the suspension,” says Dr. Shiigi.

Further, he notes that the standard MTT assay is used as a colorimetric method but requires sufficient incubation time to obtain absorbance. The team found that MTT has electrochemical activity and by “focusing on its current response, highly sensitive measurement became possible.”

The research team has developed the technique based on opinions obtained from interviews with several food product manufacturers in Japan.

“We believe that the product is highly marketable. The plan is to proceed with development with a focus on device realization in the future,” he concludes.

Their results were published in Analytical Chemistry.

Reference:

Journal: Analytical ChemistryTitle: Evaluation of Bacterial Activity Based on the Electrochemical Properties of Tetrazolium SaltsDOI: 10.1021/acs.analchem.3c01871Author: Hikaru Ikeda, Akira Tokonami, Shigeki Nishii, Xueling Shan, Yojiro Yamamoto, Yasuhiro Sadanaga, Zhidong Chen, and Hiroshi ShiigiPublished: August 10, 2023

Abstract

This study focused on the electrochemical properties of tetrazolium salts to develop a simple method for evaluating viable bacterial counts, which are indicators of hygiene control at food and pharmaceutical manufacturing sites. Given that the oxidized form of 3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), which has excellent cell membrane permeability, changes to the insoluble reduced form of formazan inside the cell, the number of viable cells was estimated by focusing on the reduction current of MTT remaining in the suspension. Dissolved oxygen is an important substance for bacterial activity; however, it interferes with the electrochemical response of MTT. We investigated the electrochemical properties of MTT to obtain a potential-selective current response that was not affected by dissolved oxygen. Real-time observation of viable bacteria in suspension revealed that uptake of MTT into bacteria was completed within 10 min, including the lag period. In addition, we observed that the current response depends on viable cell density regardless of the bacterial species present. Our method enables a rapid estimation of the number of viable bacteria, making it possible to confirm the safety of food products before they are shipped from the factory and thereby prevent food poisoning.

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