Scientists develop sensor for early detection of Alzheimer’s – ScienceDaily

Researchers at the SFU Nanodevice Fabrication Group are developing a new biosensor that could be used to detect Alzheimer’s and other diseases. An overview of their work was recently published in the journal Nature Communications.

Their sensor works by detecting a specific type of small protein, in this case a cytokine known as tumor necrosis factor alpha (TNF alpha), which is involved in inflammation in the body. Abnormal cytokine levels have been linked to a variety of diseases including Alzheimer’s disease, cancers, heart disease, autoimmune diseases, and cardiovascular disease.

TNF alpha can act as a biomarker, a measurable characteristic that indicates health status.

COVID-19 can also cause inflammatory reactions known as ‘cytokine storms’, and studies have shown that cytokine inhibitors are an effective treatment for improving chances of survival.

“Our goal is to develop a sensor that is less invasive, less expensive, and easier to use than existing methods,” says Associate Professor of Engineering Science Michael Adachi, co-leader of the project.

“These sensors are also small and could be placed in doctors’ offices to help diagnose various diseases, including Alzheimer’s disease.”

Adachi says there are a number of established methods for detecting biomarker proteins such as enzyme-linked immunosorbent assay (ELISA) and mass spectrometry, but they have several drawbacks. These current methods are expensive, samples must be sent to a lab for testing and it may take a day or more to receive results.

He notes that their biosensor is very sensitive and can detect alpha necrosis factor at very low concentrations (10 fM) – well below concentrations normally found in healthy blood samples (200-300 fM).

Current screening tests for Alzheimer’s disease include a questionnaire to determine whether a person has symptoms, brain imaging, or a spinal tap that involves testing for biomarker proteins in a prospective patient’s cerebrospinal fluid.

The team has completed a proof-of-concept phase, demonstrating that the bipolar diode sensor is effective in detecting TNF alpha in a laboratory setting. They plan to test the biosensor in clinical trials to ensure that it will be able to effectively detect biomarker proteins within a blood sample that contains many different overlapping proteins and other substances.

“We will continue to test the device’s ability to detect the same proteins using body fluids as blood samples,” says Hamidreza Ghanbari, PhD student in engineering sciences. Another goal is to use the same device but with different receptors to discover proteins that are more specific for Alzheimer’s disease.

The researchers also submitted a provisional patent application to the Technology Licensing Office (TLO) at SFU. The project takes an interdisciplinary approach, combining leadership from Adachi in Engineering Sciences and Professors Karen Kavanagh in the Department of Physics and Miriam Rosin in Biomedical Physiology and Kinesiology (BPK).

“We need to make sure that each sensor is made exactly to the required tolerance for the concentration we’re trying to predict or detect, and that’s the real challenge,” says Kavanagh.

How it works

Kavanagh says their sensor is based on the properties of a type of semiconductor that is being studied for its two-dimensional (2D) properties, molybdenum disulfide (MoS).2). This compound has different properties compared to the common semiconductors, silicon or gallium arsenide (GaAs), which are widely used and well understood.

Sohani De Silva is a Masters of Engineering Science graduate who worked on the project and confirms that the device is based on electrical measurement.

“We basically have a semiconductor in the sensing region and when the target protein interacts with the sensor, it changes the electrical signal output,” she explains. “By measuring this change, we can measure the concentration of the protein present in the body fluids.”

The team is using a type of nanomaterial called 2D material, which is likely to be atomically thin and used as a sensor layer. DNA sequences called aptamers are applied on top of these 2D materials.

Once a biomarker protein is introduced to the surface of the sensor, it causes subtle changes in the electrical properties. By looking at the electrical output of the sensor layer, they can determine the concentration of biomarker proteins in a simple solution.

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