Parkinson’s disease is a progressive neurological condition that develops due to the gradual loss of dopamine-producing nerve cells in the brain. The most common symptoms are tremors, muscle stiffness, and slowness of movement – which gradually worsen over time.
Most people with Parkinson’s disease eventually need a medication called levodopa. The drug is absorbed by nerve cells in the brain where it is converted into dopamine, which usually helps to improve their movement problems.
But achieving the right dosage of levodopa for each patient can prove challenging. Too low and it won’t be effective – and too high and it might cause side effects that can seriously affect their quality of life. And the dosage will usually need to be increased to help keep their symptoms under control as more of their nerve cells are lost over time.
Developing tests that can accurately measure levodopa levels in clinical samples, such as blood, would help doctors to tailor the best dosage for each patient. Ideally, these should be cheap, fast, sensitive, and selective.
Among the various technologies in development, electrochemical biosensors offer several important advantages as testing devices. These include the ability to directly detect the drug in body fluids without the need for complex sample processing – and portability, enabling ‘on the spot’ analysis.
In a new study, researchers set out to create a new electrochemical biosensor that can accurately measure levodopa levels in complex samples.1
Their new system involves a differential dual–strip method based on coulometry. In one strip, levodopa is converted to another chemical via a reaction catalysed by tyrosinase – while in the other, which contains no enzyme, the drug is directly oxidized. The levels of levodopa in the sample are then calculated from the difference between the two signals.
The team showed that their system could detect levodopa dissolved in aqueous solutions with high sensitivity and a low detection limit. They went on to prove that it was stable in effectively distinguishing levodopa from more complex samples containing other substances that might interfere with the results, including serum.
The researchers prepared all aqueous solutions using ultrapure water obtained from an ELGA PURELAB® laboratory water purification system, minimising the risk of adding contaminants that may affect their results.
In this study, researchers create a new electrochemical biosensor and prove that it can accurately detect levodopa within complex samples, including serum.
The system can be produced using screen-printing, which is seen as one of the most important technologies for the fast, cheap, and mass production of biosensors.
With advantages including high sensitivity, a low detection limit, high stability, low cost and simple manufacturing, the proposed technology has great potential for clinical application for levodopa dosing control for patients with Parkinson’s disease.
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1. Yu, C. et al. Differential coulometry based on dual screen–printed strips for high accuracy levodopa determination towards Parkinson’s disease management. J Pharm Biomed Analysis 2020;190:113498 doi: https://doi.org/10.1016/j.jpba.2020.113498
Dr Alison Halliday
After completing an undergraduate degree in Biochemistry & Genetics at Sheffield University, Alison was awarded a PhD in Human Molecular Genetics at the University of Newcastle. She carried out five years as a Senior Postdoctoral Research Fellow at UCL, investigating the genes involved in childhood obesity syndrome. Moving into science communications, she spent ten years at Cancer Research UK engaging the public about the charity’s work. She now specialises in writing about research across the life sciences, medicine and health.