Elastic strain engineering offers a new route to enable high-performance catalysts, electrochemical energy conversion devices, separation membranes and memristors. By applying mechanical stress, the inherent energy landscape of reactions involved in the material can be altered. This is the so-called mechano-chemical coupling. Here we discuss how elastic strain activates reactions on metals and oxides. We also present analogies to strained polymer reactions. A rich set of investigations have been performed on strained metal surfaces over the last 15 years, and the mechanistic reasons behind strain-induced reactivity are explained by an electronic structure model. On the other hand, the potential of strain engineering of oxides for catalytic and energy applications has been largely underexplored. In oxides, mechanical stress couples to reaction and diffusion kinetics by altering the oxygen defect formation enthalpy, migration energy barrier, adsorption energy, dissociation barrier, and charge transfer barrier. A generalization of the principles for stress activated reactions from polymers to metals to oxides is offered, and the prospect of using elastic strain to tune reaction and diffusion kinetics in functional oxides is discussed.

After a decade of active research, pressure is mounting for clinical translation of nanomedicines. However, to enable success in the clinic, it is important to understand the factors that can pose challenges. For example, reduction in adverse effects alone might not be enough of a driver today for clinical translation. The benchmark for clinical translation will be increased efficacy, a significant challenge to overcome if nanomedicines are developed only from a drug delivery perspective. Success in clinics will therefore require a re-examination of the design of nanomedicines, including challenging current dogmas. What can we learn from translational experience with recently approved antibody-drug conjugates, which like nanomedicines is another approach to deliver chemotherapy agents selectively to the tumors? Nanomedicines can address some of the emerging challenges in cancer chemotherapy, including heterogeneity and adaptive resistance, which can offer unique translational opportunities. This article addresses some of these themes and strategies that can facilitate translation of nanomedicines to the clinic.

A number of studies have suggested that molecular materials could offer similar performance as, or even potentially supersede, those of inorganic materials in spintronics devices. Radically new spintronics functionalities, unavailable with conventional inorganic materials, could stem from the interface between ferromagnetic (FM) and molecular materials, giving rise to the so-called “spinterface” field. In this article, we review the fundamental concepts, recent experiments, and perspectives in this fast rising field, where the functionality is brought from the bulk to the ultimate downscaled device: the interface. The article shows how spin-dependent hybridization at the FM metal/molecule interface can lead to induced spin polarization in the molecular orbitals thanks to spin-dependent broadening and energy shifting of the molecular levels. Interfacial spin polarization can then be tailored thanks to chemical interactions. Examples of enhancement and reversal are given, and we highlight how this spin-dependent hybridization opens a new door for the spintronics crafting of multifunctionality through chemical designing and tuning on the molecular scale.

Clay minerals are layered magnesium or aluminum silicates, which are abundant in the earth’s crust. Used since ancient times for the fabrication of bricks or terracotta, they now find application in the pharmaceutical and plastics industries. They play an essential role in oil and gas recovery, in water availability, and in preventing the dissemination of pollutants. In all of these contexts, the relevant properties of clay minerals are intimately linked to their microscopic structure, which results in a rich behavior with respect to water, solutes, and other fluids. This article provides a brief overview of the structure, dynamics, thermodynamics, and reactivity of water in clays, highlighting the role of the various types of water–mineral interfaces. Based on recent experimental and simulation studies, we discuss several features of these interfacial materials arising from their interactions with water on the molecular scale, including swelling, wetting, hydrodynamics in clay nanopores, reactivity of clay edge sites, ion exchange, and sorption.

Electrons in topological insulators possess unique electronic band structures and spin properties, promising a novel route to engineer material properties for electronics and energy science. Enhancing the surface state signal in electron transport is critical for both fundamental study of the surface states and future applications. Nanostructures of topological insulators naturally have large surface-to-volume ratios, effectively increasing the surface transport compared to the bulk contribution. Moreover, the unique morphology of topological insulator nanostructures results in various quantum effects of electronic states, which can tailor the surface band via quantum confinement. Here we review recent progress in topological insulator nanostructures. Material design and electron transport of topological insulator nanostructures are introduced, with an emphasis on the unique properties of nanostructures. A few examples of applications and future perspective in using these nanostructures are also discussed.

Tissue engineering and regenerative medicine aim to achieve functional restoration of tissue or cells damaged through disease, aging, or trauma. Advancement of tissue engineering requires innovation in the field of three-dimensional scaffolding and functionalization with bioactive molecules. Nanotechnology offers advanced materials with patterned nano-morphologies for cell growth and different molecular substrates that can support cell survival and functions. Cerium oxide nanoparticles (nanoceria) can control intracellular as well as extracellular reactive oxygen and nitrogen species. Recent findings suggest that nanoceria can enhance long-term cell survival, enable cell migration and proliferation, and promote stem cell differentiation. Moreover, the self-regenerative property of nanoceria permits a small dose to remain catalytically active for an extended time. This review summarizes the possibilities and applications of nanoceria in the field of tissue engineering and regenerative medicine.

The success of high capacity energy storage systems based on lithium (Li) batteries relies on the realization of the promise of Li-metal anodes. Li metal has many advantageous properties, including an extremely high theoretical specific capacity (3860 mAh g–1), the lowest electrochemical potential (–3.040 V versus standard hydrogen electrode), and low density (0.59 g cm–3), which, all together, make it a very desirable electrode for energy storage devices. However, while primary Li batteries are used for numerous commercial applications, rechargeable Li-metal batteries that utilize Li-metal anodes have not been as successful. This article discusses the properties of Li metal in the absence of surface stabilization, as well as three different approaches currently under investigation for stabilizing the surface of Li metal to control its reactivity within the electrochemical environment of a Li-based battery.

Theranostics was proposed as a combined process of therapeutics and diagnostics methodology for increasing treatment efficacy and safety with simultaneous monitoring of the response to treatment. In the past two decades, nanotechnology has been the focus of developing strategies for drug delivery and imaging functions, and it has expanded to the design of multifunctional nanoparticles and the creation of “nanotheranostics” (i.e., theranostic nanomedicines). Nanotheranostics also shows potential in gene therapy; however, nanoparticle-mediated delivery of genes still faces major obstacles related to (1) the uptake by the reticuloendothelial system, (2) the ability to get across the target cell membranes through endocytosis, and (3) the ability to accumulate in organs with permeable vasculature. Here, we review the development and application of nanotheranostics, highlighting their relevance to gene therapy as well as molecular imaging.

Recent advances in biotechnology have fueled a need for well-defined, highly stable interfaces modified with a variety of biomolecules. Diamond is a particularly attractive material for biological applications because of its chemical stability and good biocompatibility. Since diamond can be made conductive by doping, it is also of interest for a variety of electrically based biological sensing applications that achieve improved performance through selective biological modification. Recent developments of diamond growth by chemical vapor deposition have enabled the preparation of large-area synthetic diamond films on different substrates at a reasonable cost. An as-grown diamond film is terminated by hydrogen on the surface and shows hydrophobic wetting characteristics, besides chemical inertness. This has created problems for attachment of many biomolecules that are inherently hydrophilic. The challenge to make diamond useful for in vivo applications thus lies in covalently linking biomolecules to such surfaces. Several breakthroughs have been accomplished over the last decade, and attaching biomolecules to diamond in a controlled and reproducible way can nowadays be achieved in several different manners and is the focus of this article.

The possible use of spin and magnets in place of charge and capacitors, respectively, to store and process information is well known. Magnetic tunnel junctions are being widely investigated and developed for magnetic random access memories. These are two terminal devices that change their resistance based on switchable magnetization of magnetic materials. They utilize the interaction between electron spin and magnets to read information from the magnets and write onto them. Such advances in memory devices could also translate into a new class of logic devices that offer the advantage of nonvolatile and reconfigurable information processing over transistors. Logic devices having a transistor-like gain and directionality could be used to build integrated circuits without the need for transistor-based amplifiers and clocks at every stage. We review device characteristics and basic logic gates that compute with spins and magnets from the mesoscopic to the atomic scale, as well as materials, integration, and fabrication challenges and methods.

This article reviews recent developments and applications of two beam systems (focused ion beam [FIB] and scanning electron microscope [SEM]) for in situ characterization and manipulation of material at the micro- and nanoscale. In these applications, the sample may be manipulated, ion milled, mechanically or electrically excited, and its temperature varied from above room temperature to cryogenic levels. FIB-SEM instruments offer new opportunities for in situ characterization by enabling localized exposure of surface layers within the high vacuum microscope chamber environment (especially in conjunction with cryogenic cooling of the bulk sample), through experiments that require either highly accurate material removal or localized material addition through beam-induced gas deposition, and by using micro- and nano-manipulation technologies for probing or positioning. This article describes the current state of the art of this experimental methodology and provides case studies in the areas of cryogenic, electrical, and mechanical characterization.

Electrochemical ceramic cells such as solid-oxide fuel cells (SOFCs) are typically operated at 700–800°C in order to realize practical performances that, in turn, result in higher efficiencies compared to that of other types of electrochemical cells. High-temperature operation, on the other hand, leads to increased system cost and limits application. Thus, lowering the operating temperature is expected to solve such problems. This article shows the effectiveness of redesigning the cell structure for reduction of the operating temperature to 650°C or lower using conventional SOFC materials. A microtubular cell design is found to be one means of lowering the operating temperature of SOFCs. Such developments in fabrication technology are key to realizing high-performance cells with a thin electrolyte and controlled electrode microstructures.

The ability to image and quantify material behavior in real time at nano to near-macro length scales, preferably in three dimensions, is a crucial feature of modern materials science. Here, we examine such an approach to characterize the mechanical properties of three diverse classes of materials: (1) biological materials, principally bone, using both in situ small-/wide-angle x-ray scattering/diffraction to probe nanoscale deformation behavior and x-ray computed microtomography to study microscale damage mechanisms; (2) biomimetic materials, specifically a nacre-like ceramic, where microtomography is used to identify toughening mechanisms; (3) synthetic materials, specifically ceramic textile composites, using in situ microtomography to quantify the salient mechanical damage at ultrahigh temperatures. The mechanistic insights for the understanding of damage evolution and fracture afforded by these techniques are undeniable; as such, they can help provide a basis for the achievement of enhanced damage tolerance in structural materials.

Engineered nanoparticles, in particular metal oxide nanoparticles, with their unique and novel properties, enable a plethora of new applications in various fields of research. These new properties have raised concerns about potential adverse effects for the environment and human health and are nowadays very controversial. A reliable, cost- and time-effective, rapid and mechanistic-based testing strategy is needed to replace current conventional phenomenological assessments. Today’s in vitro technology, providing human-based advanced cellular models representing different organ barriers such as skin, lung, placenta, or liver, may cover this need. The aim of this article is to present the current changes in (nano) toxicology strategies, the extent to which in vitro models have achieved general acceptance, and how the relevance of these models can further be improved using examples of selected metal oxide nanoparticles.

Organic materials are fascinating and promising candidates for nanoscale spintronic devices and may open viable routes toward quantum computing. Previous experiments on spin transport in organic devices, through break junctions or spin valves, unveiled exciting new frontiers of molecular magnetism. However, much more effort is needed to understand the properties of organic/magnetic interfaces at a microscopic level. In this article, we show how spin-polarized scanning tunneling microscopy and spectroscopy (SP-STM/STS) can provide unprecedented insights into organic/magnetic interfaces as an initial step toward favorably tailoring such interfaces in order to increase device efficiency. Based on the unique combination of spin-sensitivity, atomic-scale spatial resolution, and high-energy resolution, SP-STM/STS has proven to be an invaluable method for exploring spatial and bias dependences of spin-polarized currents through individual molecules as well as for revealing individual spin-split molecular orbitals interacting with ferromagnetic substrates.

This article summarizes recent technological improvements of focused ion beam tomography. New in-lens (in-column) detectors have a higher sensitivity for low energy electrons. In combination with energy filtering, this leads to better results for phase segmentation and quantitative analysis. The quality of the 3D reconstructions is also improved with a refined drift correction procedure. In addition, the new scanning strategies can increase the acquisition speed significantly. Furthermore, fast spectral and elemental mappings with silicon drift detectors open up new possibilities in chemical analysis. Examples of a porous superconductor and a solder with various precipitates are presented, which illustrate that combined analysis of two simultaneous detector signals (secondary and backscattered electrons) provides reliable segmentation results even for very complex 3D microstructures. In addition, high throughput elemental analysis is illustrated for a multi-phase Ni-Ti stainless steel. Overall, the improvements in resolution, contrast, stability, and throughput open new possibilities for 3D analysis of nanostructured materials.

Improving the biological relevance of organs-on-chips is one of the main issues in biomedical engineering. The microvascular system is related to numerous biological phenomena throughout the life of organs. Although many in vitro microvascular systems have been developed, current organ-on-chip systems fail to fully integrate three-dimensional microvasculature, which results in decreased similarity of the systems with in vivo conditions. In this review, we propose that the microvascular system is an essential component for engineering organs-on-chips to achieve greater biological relevance. Various methods for engineering microvessels in vitro are reviewed, as well as recent representative efforts to engineer vascularized organs-on-chips. Material considerations for designing organs-on-chips are also reviewed.

Deformation is one of the most fundamental aspects of materials. While mechanical failure is an outcome of deformation to be avoided, elastic deformation can have a pronounced and positive impact on materials properties. The effect of elastic deformation becomes even more evident at low dimensions, because at the micro/nanoscale, materials and structures can usually sustain exceptionally high elastic strains before failure. The purpose of this overview is to present a summary of recent progress on elastically strained nanowires and atomic sheets. First, we will demonstrate that nanowires can sustain large elastic strains, and their bending modulus increases exponentially as the nanowire diameter decreases. Second, the elastic strain has been found to significantly modify the electronic structure of semiconductor nano/microwires to induce a metal–insulator transition at room temperature and to efficiently transform the mechanical energy into electricity. These recent developments point to potential future applications based on the elastic strain engineering of nanoscale materials.

Phase change memory (PCM) is an emerging technology that combines the unique properties of phase change materials with the potential for novel memory devices, which can help lead to new computer architectures. Phase change materials store information in their amorphous and crystalline phases, which can be reversibly switched by the application of an external voltage. This article describes the advantages and challenges of PCM. The physical properties of phase change materials that enable data storage are described, and our current knowledge of the phase change processes is summarized. Various designs of PCM devices with their respective advantages and integration challenges are presented. The scaling limits of PCM are addressed, and its performance is compared to competing existing and emerging memory technologies. Finally, potential new applications of phase change devices such as neuromorphic computing and phase change logic are outlined.

Surfaces and interfaces determine the performance and long-term durability of solid-oxide fuel cells (SOFCs). In most cases, the surface chemical composition of the materials used in these electrochemical energy conversion devices shows significant deviations from the bulk chemistry. This might be as a result of surface cation segregation processes, as well as long-term surface poisoning due to external impurities. Both processes have implications for the electrochemical performance of the devices, leading to the degradation of the cell components. In order to suppress this degradation, an effort to lower the operation temperature to 500–800°C has been made. This article provides an overview of present research progress related to surface segregation and poisoning for low-temperature SOFCs.