By Frieda Wiley
October 24, 2019 | The world of medicine is continually seeking new methods to improve health outcomes through a variety of innovative mechanisms, and accelerated diagnostics is no exception. Now, scientists may have a faster, easier way to diagnose and catch certain diseases earlier thanks to a new dopamine detector.
The device employs a plasmonic sensor—a type of technology that uses matter in the form of plasma, called plasmons, to accelerate the speed of reactions. These sensors also enhance the degree by which the plasmons respond to specific analytes (such as dopamine) to speed up those reactions.
"Plasmonic sensors are promising, but they've been poorly explored in the context of the direct biomarker detection using biological samples such as blood—with or without minimal sample preparations," says Abraham Vazquez-Guardado. "The most important contribution of [our research] is that it demonstrates the feasibility of translating this technology toward biomarker detection."
According to Vazquez-Guardado, plasmonic sensors have been in existence for nearly 20 years. His research presents a new application of this technology. It was published late last year in NanoLetters (DOI: 10.1021/acs.nanolett.8b04253).
Dopamine is a neurotransmitter that alters mood, behavior, and bodily functions when it binds to receptors in the brain. Although immortalized in the dopamine hypothesis, a theory that says too much dopamine causes Parkinson's disease, a lack of dopamine causes psychotic disorders such as that seen in schizophrenia. Abnormal dopamine levels have been linked to many other conditions, including Huntington's disease, depression, and certain cancers, such as pheochromocytoma and neuroblastoma.
Beyond the scientific community, medical professionals recognize the potential value that enhanced diagnostics can offer.
"The dopamine pathway is well-known to affect blood pressure and neurological function," says Andrew Freeman, the director of clinical cardiology, director of cardiovascular prevention and wellness, and an associate professor of medicine at National Jewish Health in Denver, Colorado. "Better understanding of what derails the pathway could have important clinical implications and disease management."
In fact, detecting abnormal dopamine at lower levels than currently possible may offer two medical advantages. More sensitive detection may help medical professionals catch diseases in earlier stages before symptoms spiral out of control, and increased dopamine-detecting sensitivity may also help prevent certain conditions if caught early enough.
How Low Can You Go?
The biosensor Vazquez-Guardado developed works by detecting dopamine in much lower concentrations than conventional methods currently used such as enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC)—on the magnitude of Femto-levels.
And the device is fast. Traditional preparations require the dopamine sample to be prepared for analysis. After using either HPLC or ELISA to detect the amount of sample, researchers must conduct a second laboratory procedure to assess how much dopamine the sample contains. Not only do the additional steps take more time, but the overall process is costly and labor-intensive.
Vazquez-Guardado and his team's biosensor is a single-step process that results in faster and cheaper analyses.
"[Our device] is a noninvasive technique that detects dopamine directly from the blood based on a simple optical measurement without needing to prepare a sample," says Debashis Chanda, Ph.D., associate professor of physics at the nanoscience technology center at the University of Central Florida in Orlando. "The sensor fabrication is based on a simple imprinting technique which further makes it low cost."
However, the scientists who developed the device say it will be a while before the device is available for commercial use.
"At this time we are focusing on the sensor optimization and performance improvement etc., but the key bottleneck is the funding for the product development," says Chanda. "With substantial funding, the development time can be reduced significantly."
In particular, the researchers want to refine the device's mechanisms by including some features that allow automation to run the assay. They also seek to expand the device's analytical capabilities to include other neurotransmitters. After making these improvements, Vazquez-Guardado says they will also need to conduct clinical trials to answer questions regarding the biosensor's precision and accuracy to support its clearance by the FDA as a medical device.
Even after securing the necessary funding to accelerate the biosensor's path to market, Vazquez-Guardado says completing all these tasks could take roughly a decade to develop.
In the meantime, conventional techniques will have to suffice while the medical community waits.