Review Articles

The clinical application of vaccines has expanded from infectious diseases to cancer, enhancing our vision of how the immune system can be used to prevent and treat disease. This Review highlights recent developments, clinical successes and future challenges in the design of prophylactic, therapeutic and tolerance-inducing synthetic vaccines with inspiration from the natural immune system.

The use of macroscopic depots to deliver drugs — including small molecules, protein and cells — at the desired treatment site by using a carrier whose physical and chemical properties control the presentation of the drug increases drug effectiveness and reduces side effects. This Review discusses the advantages of macroscopic drug-delivery systems, the associated mechanisms of spatiotemporal control of drug presentation, and the design and use of multifunctional macroscopic drug-delivery devices.

Nanoscale materials that deliver drugs in response to specific stimuli offer enhanced control of the drugs' release profile and distribution. This Review provides a comprehensive discussion of progress during the past five years in the design of nanoscale systems that can respond to exogenous stimuli such as temperature or variations in light or magnetic-field intensities, or to endogenous stimuli such as redox gradients or changes in pH or enzyme concentration.

Semiconducting quantum dots are considered candidate materials for realizing spin-based quantum computation devices. This Review examines the main results obtained over the past decade concerning the so-called central spin problem, namely the interaction between a single electronic spin or hole with the surrounding nuclear environment.

Single spins trapped in self-assembled quantum dots present rich opportunities for studying their quantum mechanical properties. This Review surveys their optical properties, and the techniques for initializing, manipulating and reading out single spin qubits in these structures.

High-throughput computational approaches combining thermodynamic and electronic-structure methods with data mining and database construction are increasingly used to analyse huge amounts of data for the discovery and design of new materials. This Review provides an overall perspective of the field for a broad range of materials, and discusses upcoming challenges and opportunities.

Metamaterials are man-made structures that allow optical properties to be shaped on length scales far smaller than the wavelength of light. Although metamaterials were initially considered mainly for static applications, this Review summarizes efforts towards an active functionality that enables a much broader range of photonic device applications.

When water binds to solid surfaces it forms a large variety of structures, which leads to behaviour relevant to many technological processes and phenomena such as lubrication, heterogeneous catalysis and electrochemistry. This Review discusses current understanding of the interface between water and flat metal surfaces at the atomic and molecular levels, as well as open questions in this field.

Metamaterials have a tremendous potential for applications from biophotonics to optical circuits, although progress has been hampered by intrinsic metal losses. This Review discusses the progress in countering such losses through the use of gain media to realize devices such as nanoplasmonic lasers or improved metamaterials for imaging and nonlinear optical applications.

The spin Hall effect is a relativistic spin–orbit coupling phenomenon, which can be used to electrically generate or detect spin currents in non-magnetic systems. This Review discusses the experiments that have established the basic physical understanding of the effect, and the role that several of the spin Hall devices have had in the demonstration of spintronic functionalities and physical phenomena.

Control of the electron spin as well as its charge is predicted to lead to efficient electronic devices, with potentially new functionalities. Injecting and manipulating spin-polarized carriers in silicon is a natural step towards integrating spintronics with current technology. This Review describes the first encouraging results as well as the open questions and challenges that still remain.

Spin caloritronics focuses on the interaction of electron spins with heat currents. This Review describes newly discovered physical effects that have re-invigorated the field by stimulating further research into understanding the fundamentals of spin–phonon interactions, and providing new avenues to explore to improve current thermoelectric technology.

Spin-transfer torque is the rotation that a spin-polarized current induces on the magnetization of the solid it flows through. The way in which currents generate torques in a wide variety of magnetic materials and structures is discussed in this Review, as well as recent state-of-the-art demonstrations of current-induced-torque devices that show great promise for enhancing the functionality of semiconductor devices.

From magnetism, ferroelectricity and superconductivity to electrical and thermal properties, oxides show a broad range of phenomena of fundamental as well as practical relevance. Reviewed here are the emergent phenomena arising at the interface between oxide materials, which have attracted considerable interest based on advances in thin-film deposition techniques.

The amount of energy that can be stored in Li-ion batteries is insufficient for the long-term needs of society, for example, for use in extended-range electric vehicles. Here, the energy-storage capabilities of Li–O₂ and Li–S batteries are compared with that of Li-ion, their performances are reviewed, and the challenges that need to be overcome if such batteries are to succeed are highlighted.

Although heterogeneous photocatalysts for converting solar to chemical energy are mostly semiconductors, metallic plasmonic nanostructures have started to attract interest. Recent progress on plasmon-enhanced, water-splitting composite photocatalysts and photocatalytic reactions on the surface of plasmonic nanostructures of noble metals are now reviewed.

Poisson's ratio describes the resistance of a material to distort under mechanical load rather than to alter in volume. On the bicentenary of the publication of Poisson's Traité de Mécanique, the continuing relevance of Poisson's ratio in the understanding of modern materials is reviewed.

The thermal properties of nanostructures have become a fundamental topic owing to the necessity of heat removal in increasingly smaller electronic devices. Carbon allotropes present a range of intriguing thermal features, with the thermal conductivity spanning five orders of magnitude at room temperature. The topic is reviewed here with particular emphasis on graphene, which exhibits the highest thermal conductivity observed.

The presence of metal centres in synthetic polymers can impart interesting functionality on the resultant material. This Review Article focuses on the use of metal-containing polymers in a diverse range of applications, for example, in emissive and optical materials, in nanomaterials, as sensors, stimuli-responsive gels, catalysts and artifical metalloenzymes.

Single dopants in semiconductors have an atom-like electron-energy spectrum whose discrete character gives them the potential for applications such as quantum information or transistors. This Review describes the marked advances in the past decade towards observing, controllably creating and manipulating single dopants, as well as their application in devices.