Endowing Ferroelectric Properties of Tetragonal Lysozyme Crystals through C₆₀ Doping

The inherent nonpolarity of tetragonal lysozyme crystals excludes a ferroelectricity response. Herein, we present a demonstration of achieving measurable ferroelectricity in tetragonal lysozyme crystals through C₆₀ doping. Ferroelectric characterizations revealed that C₆₀-doped tetragonal lysozyme crystals exhibited typical characteristic ferroelectric hysteresis loops. Crystallographic structural analysis suggested that C₆₀ doping may induce a reduction in the overall symmetry of tetragonal Lys@C₆₀, leading to the observed ferroelectricity response. Moreover, the introduction of C₆₀ facilitates efficient electron transport inside the crystal and influences the polarization of Lys@C₆₀, further contributing to the observed ferroelectricity response. This work verifies that C₆₀ doping can serve as a simple strategy to bestow novel ferroelectric properties to non-ferroelectric lysozyme crystals, potentially rendering them suitable for biocompatible and biodegradable application in implantable and wearable bioelectronics.