Development of 2D and 3D Conductive Biomaterial Composites for Use as Electromechanical Actuators

Flexible and conductive biocompatible materials are attractive candidates for a wide range of biomedical applications including implantable electrodes, tissue engineering, and controlled drug delivery. Here we demonstrated that chemical and electrochemical polymerization techniques can be combined to create highly versatile silk-conducting polymer (silk-CP) composites with enhanced conductivity and electrochemical stability. Interpenetrating silk-CP composites were first generated via in situ deposition of polypyrrole during chemical polymerization of pyrrole. These composites were sufficiently conductive to serve as working electrodes for electropolymerization, allowing an additional layer of CP to be deposited on the surface. This two-step technique expanded the range of available polymers and dopants suitable for the synthesis of mechanically robust, biocompatible, and highly conductive silk-based materials. The sequential method was applied to 2D films, 3D sponge-like silk scaffolds, and electrospun silk fibers, allowing the fabrication of conductive materials with biomimetic architectures. The electrospun fibers were able to be prepared with a high degree of alignment and permeability that was conserved during modification with conducting polymers. These electrospun materials were utilized to fabricate electromechanical actuators. The mechanism, performance, and efficacy under extended cycling of the actuator devices were analyzed in biomimetic electrolyte solutions.