Fig. 3: Piezoelectricity and biocompatibility of DL-alanine biocrystal network.

a PFM amplitude (top) and phase (bottom) responses of a single MF (left), bifurcated MFs (middle), and a MF cross (right). b Large-area unpolarized second harmonic generation (SHG) image of DL-alanine network showing uniform polarization contrast. c Polarized SHG images of the MF networks under excitation linear polarization orientation varying from 0 degree to 90 degrees. d Current output and in-plane effective piezoelectric coefficient of the MF network under various tensile strains in response to a 1 Hz and 3 N normal tapping force applying at the center. Electrode configuration and effective directions are indicated in the top schematic figure. n = 5 for each group. The error bars represent standard deviations. All data in Fig. 3d are presented as mean ± s.d. e Quantitative cell viability analysis and comparison during a 3-day culturing period. n = 6 for each group. The error bars represent standard deviations. All data in Fig. 3e are presented as mean ± s.d. Colors represent the concentration of DL alanine in culture media solutions. f Fluorescence microscopy images showing the normal morphology evolution of cells cultured in a DM solution with various amounts of DL-alanine dissolved inside during a three-day period.