Macroscopic Properties of Biomimetic Ceramics Are Governed by the Molecular Recognition at the Bioorganic–Inorganic Interface

Abstract

Bioinspired materials design aims for high-performing composite materials based on natural biomineralization processes and biomineral architectures.A key component to the research is the bioorganic-inorganic interface, one of the most crucial parameters for controlling the material properties. In this study, genetically engineered phages expressing an inorganic-binding peptide for the molecular recognition of a ceramic material is exploited to generate thin film multilayer assemblies, with the phage template as minority component. The bioorganic-inorganic interface in the ceramic (zinc oxide, ZnO) multilayer systems is strengthened by the ZnO-binding motif HSSHH of a peptide to increase Young's modulus and hardness. Applying a point-mutated version of the peptide, DSSHH, which modulates the interface forces, shows an increased fracture toughness without deteriorating the Young's modulus and the hardness. Molecular matching of the organic phase and its modulation in order to form a specific interface is shown to be important in controlling material properties like in natural biominerals. With this tool in hand, it is not only possible to imitate the structure of biominerals but also to genetically control the molecular recognition of bioorganic molecules to induce macroscopic effects in synthetic composite materials.

Genetically Induced In Situ‐Poling for Piezo‐Active Biohybrid Nanowires

“…[15] Briefly, the mineralization solution contained three different stock solutions in a volume ratio of 1:1:1. [15] Briefly, the mineralization solution contained three different stock solutions in a volume ratio of 1:1:1.…”

“…Moreover, M13-DG phage templates with an intermediate dipole moment were established by the fusion of DG (G = glycine), where glycine is a spacer in order to obtain phage mutants with the same number of added amino acid residues. [15] The hybrid wires were synthesized in a two-step procedure ( Figure S1a, Supporting Information). The phage structure was not affected by the genetic modification and they specifically templated the deposition of ZnO nanocrystals ( Figure 1a) into a polycrystalline coating.…”

“…[15] The hybrid wires were synthesized in a two-step procedure ( Figure S1a, Supporting Information). [15] The piezoelectric properties of the ZnO/M13 phage hybrid wires were determined by piezo force microscopy (PFM) allowing the simultaneous acquisition of: (i) the sample topography, (ii) the out of plane piezoelectric response and (iii) the out of plane polarization direction. In a second step, ZnO nanocrystals were synthesized in a CBD procedure under mild conditions.…”

“…[6a] However, the nonferroelectric piezo-active materials, like zinc oxide (ZnO), gallium nitride (GaN), beryllium oxide (BeO), or cadmium sulfide (CdS), do not allow the reorientation of the polar axes. [15] For such bioinspired synthesis approaches, M13 phage templates are of specific interest. [5,7] In piezo-active materials the polarization is connected to the ordered alignment of electrical dipoles.…”

“…Various template classes, e.g., polyelectrolytes, [10] peptides, [11] or biological entities, like viruses [12] and phages, [13] have been applied to control the morphology [14] of the inorganic phase or the mechanical performance of the hybrid material. [15] For such bioinspired synthesis approaches, M13 phage templates are of specific interest. M13 phages are nonpathogenic for humans and provide a nanowire-like structure (6 × 900 nm 2 ), which is precisely replicated in bacteria.…”