Self-Assembled Piezoelectric Films from Aligned Lysozyme Protein Fibrils

Piezoelectric organic polymers are promising alternatives to their inorganic counterparts due to their mechanical flexibility, making them suitable for flexible and wearable piezoelectric devices. Biological polymers such as proteins have been reported to possess piezoelectricity, while offering additional benefits, such as biocompatibility and biodegradability. However, questions remain regarding protein piezoelectricity, such as the impact of the protein secondary structure. This study examines the piezoelectric properties of lysozyme amyloid fibril films, plasticized by polyethylene glycol (PEG). The films demonstrated a measurable d₃₃ coefficient of 1.4 ± 0.1 pCN^-1, for the optimized PEG concentration, confirming piezoelectricity. The PEG was found to hydrogen-bond with the fibrils, likely impacting the piezoelectric response of the film. Polarization imaging revealed long-range alignment of the amyloid fibrils in a circumferential arrangement. These results demonstrate the potential of using amyloid fibrils, which can be formed from various proteins, to create bulk self-assembled piezoelectric materials.