In our aging society, neurodegenerative diseases are increasing. A research team has now developed a new device that detects early biomarkers for Alzheimer's and Parkinson's in body fluids. The results of the biosensor are therefore just as accurate as those of previously common techniques. Unlike these, however, the new device is portable, non-invasive and easy to use, as the scientists report. In the future, tests for neurodegenerative diseases should be possible at home as well as in clinics and nursing homes - using blood, saliva or urine samples.
Neurodegenerative diseases such as Parkinson's and Alzheimer's, in which those affected gradually lose their mental and motor skills, are increasing in many countries. There is currently no cure for these diseases, but the earlier they are detected, the easier it is to treat and delay the symptoms. But early detection is difficult because the typical symptoms often only appear many years after the actual onset of the disease. In addition, the diagnosis requires invasive procedures that many patients shy away from or do not have access to. Currently, various imaging examinations of the brain are usually carried out on people with suspected Alzheimer's or Parkinson's disease, and cerebrospinal fluid is also taken from the spinal canal and analyzed.
According to current research, Alzheimer's disease is caused by actually soluble amyloid peptides that come together and clump together in the brain. These peptides – amyloid beta and tau peptides – serve as diagnostic molecules, called biomarkers, for Alzheimer's disease. In Parkinson's disease, certain amyloid proteins, the alpha-synuclein proteins, also cause nervous system disorders. These can also serve as biomarkers for the disease. A research group led by Tyler Andrew Bodily from the University of California in San Diego has now developed a test that can detect these biomarkers in a gentle, non-invasive and easy-to-use way.
How does the biosensor work?
For the biosensor, Bodily and his colleagues adapted a device they developed during the Covid-19 pandemic to detect the proteins of the Sars-CoV-2 virus. This was possible because the chips and other components required for biosensors have become smaller and smaller in recent years and can now be produced automatically. The device, which has now been further developed for Parkinson's and Alzheimer's, contains a chip with special transistors based on the carbon material graphene. These highly sensitive graphene field effect transistors consist of a monatomic graphene layer and multiple electrodes connected to a battery to conduct current and control the amount of current flow.
Individual DNA strands are also connected to one of the electrodes, which serve as a probe and bind specifically to the biomarkers of the diseases - either the amyloid beta, the tau or the synuclein proteins. The binding of these proteins to their specific DNA probe changes the strength of the current flow between the electrodes. The device uses this signal to detect the specific biomarkers and transmits it wirelessly to a laptop or smartphone. The biosensor is therefore based on electrochemical rather than purely chemical detection. The results can be sent directly to doctors, patients, their carers and family members.
Reliable detection of Alzheimer's and Parkinson's disease
In the study, the team tested the device with synthetic amyloid proteins as well as amyloid proteins from the brains of deceased Alzheimer's and Parkinson's patients. The experiments showed that the sensors detect the specific biomarkers for both diseases with great accuracy. The researchers report that the new technology is on a par with existing test methods. The device can still detect very low concentrations of biomarkers, so that only small sample quantities are required for the test and biomarkers can also be detected in the bodies of patients in the early stages, as Bodily and his colleagues explain.
In addition, the device works well even if the samples analyzed contain, in addition to the biomarkers, other proteins that are not relevant to the test, according to the team. This reduces the risk of false positive diagnoses. However, the tau proteins of Alzheimer's disease were more difficult to detect with the biosensor than the other biomarkers. “However, because the device examines three different biomarkers simultaneously, it can combine the results of all three to arrive at a reliable overall result,” says senior author Ratnesh Lal from the University of California, San Diego.
Approval planned soon
The University of California has already granted the biotechnology startup Ampera Life a license to use the newly developed detection technology. In further tests in hospitals and nursing homes, the researchers and the company now want to find out how reliably the biosensor detects the biomarkers for Alzheimer's and Parkinson's in patients' blood plasma, saliva and urine. If these tests go well, Ampera Life says it will soon apply for approval for the device from the US Food and Drug Administration (FDA). The aim is to bring the device onto the market within a year.
Theoretically, the biosensor can also be further modified so that it detects biomarkers for other diseases, the researchers report.
Source: Tyler Andrew Bodily (University of California – San Diego) et al., Proceedings of the National Academy of Sciences, doi: 10.1073/pnas.2311565120