Implantable Organic Transistors on Biodegradable Scaffolds for the Treatment of the Spinal Cord Injury

Neural plasticity after severe spinal cord injury (SCI) is promoted by activity stimulating treatments such as specific physiotherapeutic training, injection of pharmaceutical cues and electrical stimulation (ES). However, full or even partial recovery of neuronal functionality is difficult to be achieved with current treatments. Organic bioelectronics provides novel architectures and materials that set the basement of modern neuroprosthetics. In this thesis, an active multifunctional implantable device (AMID) is developed that is highly conformable and biodegradable while being fully biocompatible. AMID integrates a three-fold functionality crucial for future treatments of SCI: a microfluidic channel allows the precise administration of anti-inflammatory pharmaceuticals or plasticity inducing agents; patterned electrodes allow delivering of electric stimuli promoting SC plasticity; organic electrochemical transistors allow to transduce bioelectronic activity providing possible information about the regeneration status. Biodegradability opens to transient neuroprostheses that are bioresporbed within the body after the regeneration process thus reducing both chronic foreign body reaction and the needs of secondary surgeries for the removal of the implant. The work starts with the fabrication and validation of the stimulation and sensing architectures onto biodegradable scaffold. Secondary, the sensing of a relevant bioelectric signal (electrocardiogram) is performed. Then, stimulating capability of biodegradable organic transistors is demonstrated with in vitro experiments onto primary neurons and macrophages. Last, the fabrication of the implantable device is presented and preliminary results about in vivo stimulation (on animal SCI model) and implant compatibility are discussed.