Performance Of Silk-Polypyrrole Bilayer Actuators Under Biologically Relevant Conditions

Biocompatible actuators that are capable of controlled movement and can function under biologically relevant conditions are of significant interest for biomedical applications. Previously, we have demonstrated that a composite material of silk biopolymer and the conducting polymer poly(pyrrole) (PPy) can be formed into a functional bilayer bending actuator. Further, these silk-PPy composites can generate forces comparable to human muscle (>0.1 MPa) making them ideal candidates for interfacing with biological tissues. Here, we explore the performance of these silk-PPy composite bilayer actuators under biologically relevant conditions including exposure to proteins, serum, enzymes, and biologically relevant temperatures. Free-end bending actuation performance, current response, force generation, and mass degradation under these conditions were investigated. We find that under the conditions tested here, the performance of our silk-PPy composites is sensitive to both protein serum and enzyme type, as well as to the temperature at which the devices are actuated. However, the silk-PPy actuators retained their functionality under all conditions tested, demonstrating the ability to bend, generate forces, and conduct currents at comparable levels to devices tested under standard operating conditions. The results suggest that our silk-PPy actuators are promising candidates for implantation in vivo and for interfacing with biological systems. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46922.