Fabrication and Characterization of Bioactive Conjugated Polymer 3D Microstructures for Organic Bioelectronics



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The emerging field of organic bioelectronics bridges the electronic world of organic based devices with the soft and predominantly ionic world of biology. This crosstalk can occur in both directions. For example, a biochemical reaction may change the doping state of an organic material leading to generate an electronic signal. Conversely, an electrical signal from a device may stimulate a biological event. Cutting-edge researches in the field of organic bioelectronics result in development of wide range of biomedical applications including neural interfaces, biochemical delivery and drug release, biosensors and field-effective transistors. The current bioelectronics devices are mainly limited by the mechanical mismatch between the soft tissue and hard metallic materials, high electrical resistivity of materials which inhibits the signal-to-noise ratio, the none-biocompatibility that produces the acute and chronic inflammatory reaction and etc. To that end, conjugated polymers (CPs) may be a great candidate for fabrication of organic bioelectronics due to their similarities in chemical structures with biological molecules and can be engineered in various forms, including films, microcups, nanotubes, nanogrooves or any 3D structures. Additionally, conjugated polymers can be tuned through synthetic chemistry for variety of bioelectronics applications. This dissertation is focused on fabrication and characterization electrically conductive and bioactive 3D structures for organic bioelectronics applications. Two of the most common CPs poly(3,4-ethylenedioxythiophene) and polypyrrole were utilized to fabricate conductive 3D structures in various shape and geometry including microcups, aligned nanotubes, aligned nanogrooves using electrochemical polymerization and two-photon polymerization techniques. Additionally, the chemical structure of some of those CPs was chemically functionalized using laminin protein to potentially improve its biocompatibilities and the cell adhesion properties. We also introduced a novel equivalent circuit model to investigate the dependence of electrode impedance of conjugated polymers microcups on properties of CP/electrolyte interface. It was found that the morphology (i.e. height and surface area) of CPs could be precisely tuned during electrochemical polymerization. We were able to demonstrate a sustain release of anti-inflammatory agent from microcups and aligned fibers. We also showed the fabrication of highly conductive and laminin-incorporated 3D structures using two-photon polymerization. The fabricated microstructures have tremendous potential for bioelectronics applications.



Conjugated polymers, 3D structures, Drug delivery, Bioelectronics


Portions of this document appear in: Antensteiner, Martin, Milad Khorrami, Fatemeh Fallahianbijan, Ali Borhan, and Mohammad Reza Abidian. "Conducting polymer microcups for organic bioelectronics and drug delivery applications." Advanced Materials 29, no. 39 (2017): 1702576. And in: Khorrami, Milad, and Mohammad Reza Abidian. "Aligned Conducting Polymer Nanotubes for Neural Prostheses." In 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), pp. 6080-6083. IEEE, 2018. And in: Eslamian, Mohammadjavad, Milad Khorrami, Ning Yi, Sheereen Majd, and Mohammad Reza Abidian. "Electrospinning of highly aligned fibers for drug delivery applications." Journal of Materials Chemistry B 7, no. 2 (2019): 224-232.