Electroconductive Biomaterial Platforms: from Piezoresistive Sensors to Cardiac Tissue Engineering
Citation:
Solazzo, Matteo, Electroconductive Biomaterial Platforms: from Piezoresistive Sensors to Cardiac Tissue Engineering, Trinity College Dublin.School of Engineering, 2022Download Item:
Abstract:
New classes of functional materials and the rapid advances being made in manufacturing technologies are key requirements to drive the next step forward in healthcare. In recent decades, conjugated polymers have gained interest due to their electroconductive properties and ease of processability. Amongst such materials, poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) emerges as one promising candidate for long-term biomedical applications for which electrical and electronic features are key. PEDOT:PSS is dispersible in water-based solutions, benefiting of a tremendous advantage if considering the material processability. PEDOT:PSS can be directly applied as coating to pre-existing substrates via straight forward methods such as casting or dip coating, without the need of extra solvents. Furthermore, in its water-based form, PEDOT:PSS can be directly processed via ice-templating (also known as lyophilisation or freeze-drying) to obtain three-dimensional (3D) porous sponge-like constructs. To date, most studies have focussed on two-dimensional membranes or coatings, and much optimisation is required to fully translate PEDOT:PSS to 3D applications. In this thesis, I investigate strategies for the modification of 3D architectures achieved via ice-templating, determining how these impact on the electro-mechanical properties. Together, I explore new crosslinking molecules and post-treatment protocols to improve the electrical conductivity of these constructs, aiming to address the typical drop of electrical conductivity often associated with standard crosslinking methods. I then demonstrate the potential of 3D porous PEDOT:PSS from two perspectives. First, I investigate wearable sensors. Such devices are applied within medicine, fitness, robotics and are a potential tool for implementing improved personalised healthcare. Amongst these assets, piezoresistive sensors are frequently used due to their high sensitivity, simple device structure, and easy to interpret readout. Relying on the intrinsic piezoresistivity of PEDOT:PSS and on the versatility of ice-templating as manufacturing technique, I fabricated a family of sensors with diverse stiffness and microarchitecture. Studying their piezoresistivity, I explored how such features affected the performance of the sensor. Finally, the optimal combination of microarchitecture and stiffness was chosen as a candidate for the fabrication of a piezoresistive sensor prototype and the detection of simple body movements. This research then focusses on another field benefiting from the optimisation of 3D electroconductive porous scaffolds, namely tissue engineering - specifically in vitro cardiac models. Although there have been multiple improvements in pharmacological therapies, cardiovascular disease remains a leading cause of mortality and morbidity worldwide. Tissue engineering has potential to provide improved repair to the damaged myocardium, and it can enable the development of more physiologically relevant platforms for the identification and testing of new drugs. The most modern of these constructs - also known as engineered heart tissues (EHT) - have been successful in replicating specific cellular mechanisms of the contractile unit of the heart. In this context, I changed the chemistry of 3D porous PEDOT:PSS constructs, aiming to obtain scaffolds with more cardio-inductive stiffness as well as an electrical conductivity closer to that of the native myocardium. Using poly(ethylene glycol) diglycidyl ether (PEGDE) as crosslinker or alternatively a crystallisation post-treatment on glycidoxypropyl-trimethoxysilane (GOPS) crosslinked scaffolds, biocompatible constructs with enhanced softness and conductivity were obtained, resulting in more suitable candidates for the development of a scaffold-based EHT. Finally, I conceptualised, designed, and fabricated both a pacing bioreactor and a rig for the generation of electrically stimulated in vitro models combining the previously developed 3D scaffolds. This body of work is clear demonstration of PEDOT:PSS having the potential and versatility required to unlock new frontiers for biomedical engineering. I have demonstrated that it is possible to tailor the morphological and physical features of PEDOT:PSS constructs to meet their target application, and that 3D PEDOT:PSS-based scaffolds can facilitate functional guidance platforms for tissue engineering.
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https://tcdlocalportal.tcd.ie/pls/EnterApex/f?p=800:71:0::::P71_USERNAME:SOLAZZOMDescription:
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Author: Solazzo, Matteo
Advisor:
Monaghan, MichaelPublisher:
Trinity College Dublin. School of Engineering. Discipline of Mechanical & Manuf. EngType of material:
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