The ability to synthesize and assemble functional nanomaterials using proteins and peptides is an area of active research, merging various methodologies common in biochemistry and molecular biology to create a wide range of nanoscale materials with intriguing properties. These “bioenabled” nanomaterials have distinct advantages over their nonbiological counterparts, including diverse/precise chemical functionalization, benign aqueous-based processing conditions, and the inherent high specificity for targeted substrates. In parallel, the advent of synthetic biology is providing avenues to engineer novel protein chemistry and functionality, leading to commercialization in the startup sector. In this article, we provide a prospective review for fusing established methods in protein-enabled nanomaterials with those found commonly in synthetic biology. We first summarize significant findings and outcomes from the peptide and protein-enabled nanomaterials literature. The application of synthetic biology methodologies toward research areas of tangential similarity will also be summarized, including the directed evolution of enzymes for bioinorganic reactions, noncanonical amino acid engineering in proteins, and the incorporation of electrical active elements into anisotropic proteins. To conclude, we will suggest avenues for new research directions for protein-enabled nanomaterials that fully exploit the power of synthetic biology.

Living organisms have engineered remarkable protein-based materials through billions of years of evolution. These multifunctional materials have unparalleled mechanical, optical, and electronic properties and have served as inspiration for scientists to study and mimic these natural protein materials. New tools from synthetic biology are poised to revolutionize the ability to rapidly engineer and produce proteins for material applications. Specifically, advancements in new production hosts and cell-free systems are enabling researchers to overcome the significant challenges of cloning and expressing large nonnative proteins. The articles in this issue cover the mechanical and rheological properties of structural protein materials and nanocomposites; advancements in the synthesis and assembly of optical, electronic, and nanoscale protein materials; and recent development in the processing of protein materials using liquid–liquid phase separation and three-dimensional printing.

Additive manufacturing is a revolutionary three-dimensional (3D) printing technology that has applications in a vast number of fields from aerospace to biological engineering. In the field of bioengineering, it was recently discovered that the principles used in 3D bioprinting of organs and tissues could also be used to 3D print biological materials produced by genetically engineered bacteria. This new technology requires the development of modified bio-ink and optimized printing parameters to promote bacterial physiology while allowing printability. In this article, we highlight the recent advancements in additive manufacturing of engineered living materials using bacteria and their potential applications. We will discuss recent progress and significance of additive manufacturing of proteins and polypeptides produced in situ by engineered bacteria to make multifunctional materials. Finally, we discuss the challenges and prospects of this technology and highlight some of the biomaterials that may benefit from additive manufacturing with bacteria.

The orientation between twin boundary (TB) and loading direction may play an intriguing role in the deformation behaviors of twinned metallic materials. In this aspect, its essential effect on the high-entropy alloy (HEA) nanocrystals is elusive. Attention herein is focused on the atomic-scaled deformation mechanisms and fracture behaviors of HEA nanocrystals containing twins of even smaller spacings via a combined approach of in situ tensile tests inside a high-resolution transmission electron microscope and molecular dynamics simulations. The results indicate that the deformation mechanisms (especially dislocation activities) of HEA nanocrystals depend on the load orientation with respect to TBs. Because of the low activation energy and uneven local composition of HEA, the surface acts as an effective dislocation source and, together with Schmid factor, dominate the activated dislocation slip system. The load orientation-dependent TB-dislocation interactions may transform the type of fracture from semi-brittle to ductile. Our results indicate that the deformation mechanisms and the types of fracture in HEA nanocrystals can be controlled by changing the orientation.

Structural phase transitions in semiconductors have been utilized for driving technological advancements in switchable electronics and phase-change memory devices. There have been numerous reports on high susceptibility of halide perovskites to phase transitions because of their soft lattice; however, the factors affecting the underlying process are still poorly understood. Insights into the phase transition dynamics of halide perovskites are desirable for precise control of optoelectronic properties and for unlocking their use in novel solid-state applications.

Triiodide perovskites CsPbI3, CsSnI3, and FAPbI3 (where FA is formamidinium) are highly promising materials for a range of optoelectronic applications in energy conversion. However, they are thermodynamically unstable at room temperature, preferring to form low-temperature (low-T) non-perovskite phases with one-dimensional anisotropic crystal structures. While such thermodynamic behavior represents a major obstacle toward realizing high-performance devices based on their high-temperature (high-T) perovskite phases, the underlying phase transition dynamics are still not well understood. Here we use in situ optical micro-spectroscopy to quantitatively study the transition from the low-T to high-T phases in individual CsSnI3 and FAPbI3 nanowires. We reveal a large blueshift in the photoluminescence (PL) peak (~38 meV) at the low-T/high-T two-phase interface of partially transitioned FAPbI3 wire, which may result from the lattice distortion at the phase boundary. Compared to the experimentally derived activation energy of CsSnI3 (~1.93 eV), the activation energy of FAPbI3 is relatively small (~0.84 eV), indicating a lower kinetic energy barrier when transitioning from a face-sharing octahedral configuration to a corner-sharing one. Further, the phase propagation rate in CsSnI3 is observed to be relatively high, which may be attributed to a high concentration of Sn vacancies. Our results could not only facilitate a deeper understanding of phase transition dynamics in halide perovskites with anisotropic crystal structures, but also enable controllable manipulation of optoelectronic properties via local phase engineering.

It has been widely speculated that dominant motifs, such as short-range icosahedral order, can influence glass formation and the properties of glasses. Experimental data on both fragile and strong undercooled liquids show corresponding changes in their thermophysical properties consistent with increasing development of a network of interconnect motifs based on molecular dynamics. Describing these regions of local order, how they connect, and how they are related to property changes have been challenging issues, both computationally and experimentally. Yet the consensus is that metallic liquids develop interconnected medium-range order consisting of some regions with lower mobility with deeper undercooling. Less well understood is how these motifs (or “crystal genes”) in the liquid can inhibit nucleation in the deeply undercooled liquid or influence phase selection upon devitrification. These motifs tend to have local packing unlike stable compounds with icosahedral order tending to dominate the best glass formers. The underlying kinetic and thermodynamic forces that guide the formation of these motifs and how they interconnect during undercooling remain open questions.

Through diversity of composition, sequence, and interfacial structure, hybrid materials greatly expand the palette of materials available to access novel functionality. The NSF Division of Materials Research recently supported a workshop (October 17–18, 2019) aiming to (1) identify fundamental questions and potential solutions common to multiple disciplines within the hybrid materials community; (2) initiate interfield collaborations between hybrid materials researchers; and (3) raise awareness in the wider community about experimental toolsets, simulation capabilities, and shared facilities that can accelerate this research. This article reports on the outcomes of the workshop as a basis for cross-community discussion. The interdisciplinary challenges and opportunities are presented, and followed with a discussion of current areas of progress in subdisciplines including hybrid synthesis, functional surfaces, and functional interfaces.

Additive manufacturing (AM) comprises a group of transformative technologies that are likely to revolutionize manufacturing. In particular, laser-based metal AM techniques can not only fabricate parts with extreme complexity, but also provide innovative means for designing and processing new metallic systems. However, there are still several technical barriers that constrain metal AM. Overcoming these barriers requires a better understanding of the physics underlying the complex and dynamic laser–metal interaction at the heart of many AM processes. This article briefly describes the state of the art of in situ/operando synchrotron x-ray imaging and diffraction for studying metal AM, mostly the laser powder-bed fusion process. It highlights the immediate impact of operando synchrotron studies on the advancement of AM technologies, and presents future research challenges and opportunities.