By the year 2060, about 14 million Americans will suffer from Alzheimer's Disease. Other neurodegenerative diseases, such as Parkinson's, are also on the rise. Current state of the art testing methods for Alzherimer's and Parkinson's require a spinal tap and imaging tests, including an MRI. As a result, early detection of the disease is difficult, as patients balk at the invasive procedures. Testing is also difficult for patients who are already exhibiting symptoms and have difficulty moving as well as those who have no early access to local hospitals or medical facilities. A recent paper published in PNAS (Proceedings of the National Academy of Sciences) describes an innovative, wireless, handheld, non-invasive device to detect Alzheimer's and Parkinson's biomarkers. This biosensor consists of a chip with a highly sensitive transistor, made of a graphene layer that is a single atom thick and three electrodes–source and drain electrodes, connected to the positive and negative poles of a battery, to flow electric current, and a gate electrode to control the amount of current flow. Connected to the gate electrode is a single DNA strand, which serves as a probe that specifically binds to either amyloid beta, tau or synuclein proteins. The binding of these amyloids with their specific DNA strand probe, called an aptamer, changes the amount of current flow between the source and drain electrode. The change in this current or voltage is the signal used to detect the specific biomarkers, like amyloids. The research team tested the device with brain-derived amyloid proteins from Alzheimer's and Parkinson's deceased patients.
The experiments showed that the biosensors were able to detect the specific biomarkers for both conditions with great accuracy, on par with existing state of the art methods. The device also works at extremely low concentrations, meaning that it needs small quantities for samples–down to just a few microliters. In addition, the tests showed that the device performed well even when the samples analyzed contained other proteins. Tau proteins were more difficult to detect. But because the device looks at three different biomarkers, it can combine results from all three to arrive at a reliable overall result. It is expected that this portable diagnostic system would allow testing at-home and at point of care, like clinics and nursing homes, for neurodegenerative diseases globally.
Reference:
Bodily TA, Ramanathan A, Wei S, Karkisaval A, Bhatt N, Jerez C, . . . Lal R (2023) In pursuit of degenerative brain disease diagnosis: Dementia biomarkers detected by DNA aptamer-attached portable graphene biosensor. Proceedings of the National Academy of Sciences of the United States of America, 120(47):e2311565120. PMID: 37956285. URL: https://www.ncbi.nlm.nih.gov/pubmed/37956285 & https://www.pnas.org/doi/epdf/10.1073/pnas.2311565120
The experiments showed that the biosensors were able to detect the specific biomarkers for both conditions with great accuracy, on par with existing state of the art methods. The device also works at extremely low concentrations, meaning that it needs small quantities for samples–down to just a few microliters. In addition, the tests showed that the device performed well even when the samples analyzed contained other proteins. Tau proteins were more difficult to detect. But because the device looks at three different biomarkers, it can combine results from all three to arrive at a reliable overall result. It is expected that this portable diagnostic system would allow testing at-home and at point of care, like clinics and nursing homes, for neurodegenerative diseases globally.
Reference:
Bodily TA, Ramanathan A, Wei S, Karkisaval A, Bhatt N, Jerez C, . . . Lal R (2023) In pursuit of degenerative brain disease diagnosis: Dementia biomarkers detected by DNA aptamer-attached portable graphene biosensor. Proceedings of the National Academy of Sciences of the United States of America, 120(47):e2311565120. PMID: 37956285. URL: https://www.ncbi.nlm.nih.gov/pubmed/37956285 & https://www.pnas.org/doi/epdf/10.1073/pnas.2311565120