Polarization switching and patterning in self-assembled peptide tubular structures

Abstract

Self-assembled peptide nanotubes are unique nanoscale objects that have great potential for a multitude of applications, including biosensors, nanotemplates, tissue engineering, biosurfactants, etc. The discovery of strong piezoactivity and polar properties in aromatic dipeptides [A. Kholkin, N. Amdursky, I. Bdikin, E. Gazit, and G. Rosenman, ACS Nano 4, 610 (2010)] opened up a new perspective for their use as biocompatible nanoactuators, nanomotors, and molecular machines. Another, as yet unexplored functional property is the ability to switch polarization and create artificial polarization patterns useful in various electronic and optical applications. In this work, we demonstrate that diphenylalanine peptide nanotubes are indeed electrically switchable if annealed at a temperature of about 150 °C. The new orthorhombic antipolar structure that appears after annealing allows for the existence of a radial polarization component, which is directly probed by piezoresponse force microscopy (PFM) measurements. Observation of the relatively stable polarization patterns and hysteresis loops via PFM testifies to the local reorientation of molecular dipoles in the radial direction. The experimental results are complemented with rigorous molecular calculations and create a solid background of electric-field induced deformation of aromatic rings and corresponding polarization switching in this emergent material.

Self-assembly of diphenylalanine peptide with controlled polarization for power generation

“…Like antiparallel dipole moments observed in M13 phages5, the oppositely directed polarizations were revealed in adjacent FF peptide nanostructures2025. Although ferroelectric behaviour has been observed for FF nanotubes through high-temperature treatment, the polarization was only switched in the radial direction while the axial polarization was destroyed due to an irreversible phase transition to the centrosymmetric structure26. The high coercive field in the axial direction leaves native FF crystals practically unswitchable before electrical breakdown27.…”

Piezoelectricity and ferroelectricity in biomaterials: Molecular modeling and piezoresponse force microscopy measurements

“…The discovery of strong piezoelectric activity, temperature-dependent spontaneous polarization, and phase transition 41,[70][71][72] in these aromatic dipeptides established them as functional nanomaterials with a range of possible applications. The inorganic tubes made of Pb(Zr,Ti)O3 are potential candidates for microfluidics THz emission.…”

“…72 The fitted value of the Curie-Weiss point is T c % 142. 5 C with Curie-Weiss constant C wb ¼ 230 K and extrapolation shows that T cwb is about165 C. 71,72 Assuming that the phase transition in FF PNT is close to the first order, we can estimate the Curie-Weiss constant below the phase transition temperature, C wa , as %8C wb % 1840 K. 7 Moreover, this model allows us to explain the irreversible nature of the transition as revealed by SHG signal (Fig. 14(a), cooling branch): in this case, without an applied electric field, we have vanishing value of the total dipole moment due to full compensation of individual moments.…”

Piezoelectric resonators based on self-assembled diphenylalanine microtubes

“…Even more possibilities are foreseen in thermally annealed tubular structures 6 where a stable polarization switching is observed due to the rotation of the radial polarization component. 9 This will allow controlling hydrogen bond orientation, which can give additional opportunities for biofunctionalization by switching functional groups "on" and "off," i.e., by making them more or less sterically accessible.…”

“…8 In addition, after annealing above 140 150 C, FF tubes become electrically switchable in a radial direction thus opening new opportunities for information data storage applications. 9,10 Strong piezoelectricity 10 (of the order of that in LiNbO 3 ) is especially beneficial for various biosensor and mass detection applications where micromachined piezoelectric cantilevers based on inorganic materials (such as AlN, GaAs, ZnO, or piezoelectric perovskites) are currently used. 11,12 Due to the small dimensions of sensing elements and consequent increase of the resonance frequencies, piezoelectric actuation is able to provide extremely small mass sensitivity, single electron efficiency, and fast response, as opposite to magnetomotive, electrostatic, and electrothermal principles.…”