The prevalence of neurodegenerative disorders, such as Parkinson's and Alzheimer's diseases, will continue to increase as the population ages. This is expected to impose an increasing social and economic burden on societies.
Parkinson's disease is characterized mainly by motor symptoms that are caused by the progressive degeneration of neurons that synthesize and release the neurotransmitter dopamine (DA). Current treatment methods, such as levodopa administration and deep brain stimulation, alleviate the symptoms but do not alter disease progression. Therefore, there is an evident need to understand the causes and progression of the disease and to develop new treatment methods. Since the abnormal neurotransmission of DA is linked to the onset of symptoms and progression of Parkinson's disease, the real-time in vivo monitoring of DA levels could provide new information to understand the disease.
In this thesis, we have investigated the use of amorphous carbon (a-C) materials as electrochemical sensors for the sensitive and selective measurement of DA. There have been relatively few reports on the electrochemical properties of a-C, although it offers significant advantages, such as a wide potential window and a low background current, over commonly used electrode materials for sensor applications. We have studied the physical, chemical and electrochemical properties of different a-C materials using several bulk and surface characterization methods, computational simulations and electrochemical techniques with outer and inner sphere redox probes.
We have shown that deposition parameters can be varied to obtain a-C films with markedly different electrochemistry ranging from graphite-like, highly sp2-bonded carbon to diamond-like, highly sp3-bonded carbon. The sp2/sp3 bonding ratio will define the physical properties, in particular the electronic configuration that strongly correlates with the electrochemistry of a-C materials.
We have demonstrated the applicability of highly sp3-bonded tetrahedral amorphous carbon (ta-C) in electroanalytical applications by detecting physiologically relevant DA concentrations (40-85 nM) using cyclic voltammetry. The modification of ta-C with carbon nanotubes conferred the electrode the necessary selectivity to detect DA in the presence of its major interferents, ascorbic acid and uric acid, at physiological concentrations. Both the ta-C and the modified electrodes showed good biocompatibility, further emphasizing their potential as in vivo sensor materials.
|Publication status||Published - 2019|
|MoE publication type||G5 Doctoral dissertation (article)|
- electrochemistry, amorphous carbon, cyclic voltammetry, electrochemical impedance spectroscopy, dopamine, neurotransmitter