Detecting gum disease, or periodontal disease, traditionally relies on a clinical examination by a dentist, often identifying problems only after tissue damage has begun. Now, researchers at Texas A&M University have developed a wearable, tissue-adhesive biosensor designed to shift dental care from a reactive to a proactive approach, potentially preventing more serious health complications.
The biosensor, detailed in the journal Science Advances, is engineered to detect inflammation biomarkers in the mouth with what researchers describe as molecular precision. Dr. Chenglin Wu, an associate professor of civil and environmental engineering at Texas A&M, led the development and testing of the multi-layer sensor, designed to function effectively in the wet oral environment even while talking and eating.
Targeting Inflammation at a Molecular Level
The core of the biosensor’s functionality lies in its ability to target tumor necrosis factor-alpha (TNF-α), a key protein biomarker indicative of inflammation. The sensor utilizes a graphene-MXene sensing layer that binds to specific probes designed to attach only to TNF-α. This layer’s inherent conductivity allows for the measurement of changes in charge when the target protein binds, enabling highly sensitive detection.
“Our sensor could detect 100 to 150 [TNF-α proteins] per milliliter,” explained Dr. Wu, providing context. “For context, a patient with a viral infection might show symptoms at 10 million or 1 billion virus copies per milliliter.” The study demonstrated detection capabilities as low as 18.2 femtograms per milliliter (fg/mL) – a remarkably small quantity. To illustrate the sensitivity, one quadrillion femtograms equals just one gram.
Achieving this level of sensitivity presents challenges, particularly in avoiding false positives from unwanted biomarkers. However, the biosensor incorporates outer layers designed to improve selectivity, filtering out interfering molecules.
Dynamic Tissue Adhesion and Biomarker Filtering
A crucial component of the biosensor is its tissue-adhesive hydrogel, which not only secures the patch to the gumline but also features a selective-permeable hydrogel layer. This layer, engineered in collaboration with researchers at Michigan State University, acts as a filter, allowing only smaller biomarkers to pass through.
“My collaborator at Michigan State University engineered a very small opening that will only allow the smaller biomarkers through,” Dr. Wu said. “Combining that with the highly selective probe attached to the sensing layer makes for accurate selectivity.” Dr. Shaoting Lin, an assistant professor of mechanical engineering at Michigan State, contributed to the development of both the tissue-adhesive and selective-permeable hydrogel.
The robust tissue adhesion is also critical for accurate sensing. “Sensing measurements can be significantly influenced by the dynamic movement of tissues,” Dr. Lin explained. “A more robust tissue bond allows for a more reliable sensing performance independent of the strain.” The selective permeable layer functions like a mesh, controlling which molecules can pass through, and chemical interactions between the layer and biomarkers further enhance selectivity.
“We systematically tested a few biomolecules of similar size,” Dr. Lin added. “Due to the interaction between the biomolecule and the surrounding polymer network, there is an enhanced selectivity that distinguishes the transport of different biomolecules.” Future research aims to engineer hydrogels that specifically interact with various biomarkers, expanding the sensor’s capabilities.
Testing and Future Directions
The researchers tested the biosensor’s concept using guinea pigs, chosen for their similarities to humans in terms of oral inflammation. Dr. Jeffrey Cirillo, a Regents’ Professor at Texas A&M’s College of Medicine, contributed his expertise in biological applications and clinical evaluation. The focus was on detecting TNF-α, a cytokine frequently involved in inflammation associated with oral infections.
“The goal was to see if this type of system would allow rapid, point-of-care detection,” Dr. Cirillo said. The study demonstrated the feasibility of the concept, paving the way for future clinical trials in animals and, humans.
Dr. Hajime Sasaki, an associate professor of dentistry at the University of Michigan, provided insights into biomarkers and dental diseases, recognizing the importance of detecting TNF-α in the oral cavity. Oral infections, if left untreated, can lead to serious health problems like gum disease and tooth loss, and have also been linked to systemic conditions like cardiovascular disease and diabetes. Early diagnosis could enable a shift towards anticipatory oral health care.
The researchers emphasize that this technology holds potential beyond oral health. The versatility of the materials used suggests the possibility of adapting the biosensor for other parts of the body and for detecting different biomarkers, opening avenues for broader applications in personalized health monitoring.
