August 2017 NUI Galway Research Published on Deep Brain Stimulation Results

CÚRAM PhD Candidate Publishes New Research on Modified Implantable Electrode Devices Used in Deep Brain Stimulation

Catalina Vallejo, a PhD candidate at CÚRAM, the Science Foundation Ireland Centre for Research in Medical Devices, based at NUI Galway, has recently published the results of her work in the prestigious journal Advanced Functionalised Materials (AFM).

Ms Vallejo’s research focuses on the modification of implantable electrode systems to improve their performance when used, for example, in neural recording and in deep brain stimulation in patients with neurological disease such as dystonia and Parkinson’s disease. This research provides a useful benchmark for anodization conditions for further studies with neural microelectrodes, micropatterning, and biochemical functionalisation.

Catalina Vallejo’s research has shown that anodization offers the ability to modify ITO films and may provide an easier approach to the generation of electrode coatings with differential regions of charge conductance and cellular function capacities. It can be hypothesized that anodization with varying current densities may be employed to deposit insulator and charge carrier regions on a single electrode system, providing cytocompatible and functional coatings for implantable thin-film ITO devices.

Deep brain stimulation (DBS) involves implanting stimulating electrodes into the brain. Catalina’s work explored the development of a coating for these electrodes, using a bench-top electrochemical process to formulate anodized indium tin oxide (ITO) films with altered roughness, conducting profiles, and thickness.

In addition, Ms Vallejo examined the influence of these anodized films on neural cell adhesion, proliferation, and function, and showed that the compatibility of the coating with brain tissue can be altered by varying the anodization current density. She also showed how the films produced with a specific current density, increased primary neural cell survival, modulation of glial scar formation, and promotion of neural network activity when in situ in the brain.

The modification of implantable electrodes for neural stimulation has been a major focus of neural engineering over the past five years. “A common occurrence following electrode implantation is the formation of a glial ‘scar’ around the implant”, explains Catalina. “This can accelerate neural loss, increase the barriers to the flow of the electrical signal to where it’s needed in the brain and so compromises the efficacy of a stimulating/recording system in the brain. My research aimed to develop a way to improve the efficacy of these devices, resulting in a better outcome for patients.”

Traditionally, chemically inert conductors such as gold, platinum, and iridium, as well as semiconductors such as silicon, have been widely employed as electrode systems in both clinical and research settings. Recently, however, non-metallic electrically conducting biomaterials, including inherently conducting polymers and polymer composites have been explored as neuroelectrode alternatives in an effort to promote chronic functionality and enhanced biocompatibility.

Catalina’s journey through her PhD was not without its challenges. “During my first year, I was learning the basics of electrochemistry and electrodeposition and I initially intended on making electrodeposited conducting polymer films onto the surface of the ITO. I was using a very old Potentiostat, a Princeton Applied Research electrochemical Potentiostat / Galvanostat model 263A running Verastudio software. After almost a full years work, I came to understand that Potentiostat had reversed the electrode configuration/connections. This resulted in the anodization of the ITO films and not in the electrodeposition of the conducting polymer – the opposite of what I wanted to achieve.”

Commenting on Catalina’s work, Dr Manus Biggs, Principal Investigator at CÚRAM said: “Catalina is extremely dedicated and at the time the ITO process was confusing, frustrating and quite demotivating for her, but in the end we have learned a lot from this. A research career is full of enlightening errors, and this process was crucial in helping to illuminate some of the bases of her work in conducting polymers, and eventually resulted in the development of a process to formulate these anodized ITO films.”

Congratulating Catalina on her work, Professor Abhay Pandit, Scientific Director of CÚRAM said: “Ultimately, what we are trying to do at CÚRAM is to improve quality of life for patients with chronic illnesses through the development of new and enhanced implants and devices. It’s fantastic to see how our PhD candidates are contributing significantly to the knowledge base in this area.”

To read the full paper entitled ‘Preparation of Cytocompatible ITO Neuroelectrodes with Enhanced Electrochemical Characteristics Using a Facile Anodic Oxidation Process’ in the Advanced Functionalised Materials journal, visit: http://onlinelibrary.wiley.com/doi/10.1002/adfm.201605035/abstract

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