Early Alzheimer’s disease detection sensor in development

USA — Simon Fraser University (SFU) Nanodevice Fabrication Group researchers are working on a new biosensor that can be used to screen for Alzheimer’s disease and other diseases, Science Daily reports.

A summary of their findings was recently published in the journal Nature Communications.

Their sensor detects a specific type of small protein, in this case a cytokine known as Tumor Necrosis Factor alpha (TNF alpha), which is involved in cellular inflammation.

Abnormal cytokine levels have been linked to a wide range of diseases, including Alzheimer’s, cancer, heart disease, autoimmune disease, and cardiovascular disease.

TNF alpha can function as a biomarker, which is a measurable characteristic that indicates a person’s health status.

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

Our goal is to develop a sensor that’s less invasive, less expensive, and simpler to use than existing methods,” says Engineering Science Assistant Professor Michael Adachi, the project’s co-lead.

“These sensors are also small and have the potential to be placed in doctor’s offices to help diagnose different diseases, including Alzheimer’s disease.”

According to Adachi the biosensor is extremely sensitive and can detect TNF alpha in very low concentrations of 10 femtomoles (10 fM) – well below the concentrations normally found in healthy blood samples (200-300 fM).

Current screening tests for Alzheimer’s disease include a questionnaire to determine if the person has symptoms, brain imaging, or a spinal tap process which involves testing for the biomarker proteins in the cerebral spinal fluid of the potential patient.

The team completed the proof-of-concept stage, demonstrating that the two-electrode diode sensor is effective in detecting TNF alpha in a laboratory setting, according to the research published in the journal Nature Communications.

The biosensor will then be tested in clinical trials to ensure that it can detect biomarker proteins in blood samples containing a variety of interfering proteins and other substances.

We will continue testing the device’s ability to detect the same proteins using body fluid like blood samples,” says engineering science Ph.D. student Hamidreza Ghanbari.

The other objective is to use the same device but a different receptor to detect proteins that are more specific to Alzheimer’s disease.”

The researchers have also filed a provisional patent application with the Technology Licensing Office (TLO) at SFU.

The project takes an interdisciplinary approach combining leadership from Adachi in Engineering Science and professors Karen Kavanagh in the Dept. of Physics and Miriam Rosin in Biomedical Physiology and Kinesiology (BPK).

How the sensor works

According to Kavanagh, their sensor is based on the properties of molybdenum disulfide (MoS2), a type of semiconductor being studied for its two-dimensional (2D) properties.

This compound differs from common semiconductors such as silicon or gallium arsenide (GaAs), which are much more widely used and well-understood.

Thushani De Silva, a Master’s degree in Engineering Science graduate who worked on the project, emphasizes that the device is based on electrical measurement.

Basically, we have a semiconductor on the sensing area and when the targeted 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 employs a type of nanomaterial known as two-dimensional materials, which can be atomically thin and are used as the sensing layer. Aptamers, which are DNA sequences, are applied on top of these 2D materials.

When a biomarker protein is introduced onto the sensor’s surface, the electrical properties change slightly.

They can determine the concentration of these biomarker proteins in a simple solution by looking at the electrical output of the sensing layer.

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