An important signalling mechanism in chronic pain is mediated by the substance P (SP) neurokinin 1 receptor (NK1R), which is located in the acidic endosomes of sensory nervous cells, from which it generates signals that maintain the pain. NK1R antagonists have been developed, but have failed in clinical trials thus far. Ramírez-García et al. now exploit the intrinsic property of polymeric pH-responsive nanoparticles to be transported in endosomes within cells to directly deliver an FDA-approved NK1R antagonist to the acidic endosomes of spinal neurons. Upon intrathecal injection in rodents, the nanoparticles could efficiently prevent pain signal transmission, providing a potential alternative to opioids for chronic pain treatment. The cover art is an artistic impression of this nanoparticle-mediated prevention of chronic pain signal transmission in the spine.

Article by Bunnett et al.

A superlattice potential created due to the emergence of the moiré pattern in a lattice-mismatched van der Waals heterostructure has a profound effect on its resulting electronic properties. Nathan R. Finney et al. demonstrate devices consisting of monolayer graphene encapsulated between two crystals of boron nitride and observe multiple moiré patterns that can be created by adjusting the relative twist angle between the layers. Such a control knob can serve to tune the symmetry and electronic properties of the rotated heterostructures. In particular, a highly altered graphene band structure emerges when the three layers are perfectly aligned, manifested by the formation of coexisting long-wavelength moiré patterns. The cover is the artist’s depiction of such coexisting moiré structures.

Letter by Hone et al

Since the first report of the isolation of atomically thin carbon films in 2004, the field of graphene and other 2D materials has expanded dramatically. Fast forward 15 years, graphene — once established as the world's thinnest, strongest and most conductive material — remains the subject of rigorous scientific scrutiny and significant industrial interest. More than a decade of fundamental research combined with the mature graphene manufacturing methodology have created a strong basis for the future commercialization of graphene. As a reminder of the old times when graphene was still prepared by repeated peeling of graphite, the cover art shows a scanning electron microscopy image of graphene flakes — small in size, big on scientific implications.

Feature by Bubnova et al

Precision placement and transport is crucial for high-throughput autonomous molecular sorting and detection. Take nanopore sequencing as an example. The delivery of DNA molecules towards a nanopore determines the throughput and precision of the measurement. Now, using all-atom molecular dynamics, Shankla et al. find that, subject to force, molecules are more likely to move down a step defect than up the defect and are more likely to be displaced along the step defect line. The cover art depicts the tendency of adsorbed DNA molecules to move down and along the defect edge of graphene surface-step defects that separate multilayer domains. The principle can be used to guide the delivery of molecules in various technological processes.

Article by Aksimentiev et al.

High mechanical strength paired with low density and good ductility is desirable in functional materials, but difficult to achieve. Materials based on carbon nanotubes or graphene may provide a solution to this challenge if the high strength of the low-dimensional building blocks can be transferred to 3D micro- or even macrostructures. Zhang et al. now manufacture micropillars of pyrolytic carbon by means of two-photon lithography and pyrolysis. The pillars exhibit large compressive strength at low density and show rubber-like ductility; they sustain compressive strain of up to 50% without catastrophic failure. The cover art shows the atomic-scale structure of the micropillars responsible for the favourable mechanical properties. Curled graphene fragments are covalently interconnected via carbon-carbon bonds, which at the same time transfers the mechanical strength of the sp 2 carbon nanomaterial to the microscale and maintains low density.

Article by Zhang et al.

Spin waves, which can propagate free of Joule heating, may act as the information carrier in future spintronic technology. In antiferromagnets (AFMs), spin waves are fast and insensitive to external magnetic fields, but current-induced excitation and control of the propagation is difficult to achieve. Liu et al. now explore spin waves in an artificial AFM structure, which consists of periodic 100-nm-wide stripe domains with alternating upward and downward magnetization. They excite high-frequency spin waves, which propagate along the strips. Furthermore, they can reorient the domain pattern by current pulses and, thereby, control the propagation direction of the spin waves. The cover art shows spin waves propagating within domains of opposite spin polarization as indicated by the yellow and purple arrows.

Article by Yu et al

A range of nano-enabled strategies can address existing inefficiencies in agrochemical delivery and activity. Many of these approaches for plant protection and nutrition involve foliar application of engineered nanomaterials, which can also be used to enhance plant resilience and to enable biofortification. Nanotechnology clearly holds great promise for crop production, helping to sustainably meet the growing global demands for food, feed and fuel. The cover art depicts nanoparticles deposited on a leaf, interacting with the unique surface environment and subsequently entering the vascular system to deliver novel functionality to the entire plant.

See Kah et al

Unidirectional molecular motors can already perform tasks at the molecular scale, but in order to harness their properties at a larger scale, scientists are working to devise ways in which to make them work in a coordinated manner. Feringa and co-workers now show that they can embed molecular motors in the scaffold of a metal–organic framework (MOF) and that the rotation of the motor within the MOF crystals in unhindered. The cover image is a microscopy picture of MOF crystals that contain molecular motors in their structure.

See Feringa et al

Detecting plastic in complex environmental media is a challenging and time-consuming task. By synthesizing metal-doped plastics, researchers can employ commonly available analytics for trace metals analysis to more easily assess fate, transport and biological uptake of nanoplastics in experimental systems. Understanding these processes more quickly in the laboratory can shed light on their behaviour in the natural environment. Using this fundamentally different approach to circumvent some of the difficulties of detecting plastic directly, Mitrano et al. assessed the fate of nanoplastic particles in experiments representing a municipal wastewater treatment plant. Here, the authors studied the rate and extent of nanoplastic association with sludge flocs and consequently estimated their likely retention through larger-scale water treatment facilities. The cover art depicts the nanoplastic particles in suspension, with a cross section of one particle showing the finer details of the materials synthesis. Here, palladium is incorporated into a polyacrylonitrile core, with a shell of polystyrene making up the outer layer.

See Mitrano et al.

The incorporation of metal nanoparticles onto solid oxide electrochemical cell electrodes is known to be capable of improving the electrode performance substantially, especially for low-temperature operation. However, it is lack of model systems to determine the exact role of nanoparticles on the reactivity. Choi et al. prepared well-ordered arrays of monodisperse metal nanoparticles onto mixed-conducting oxide electrodes via self-assembled nanopatterning. Their constructed model electrochemical cell enables the quantitative analysis of the contribution of metal nanoparticles to the overall catalytic performance. The cover art depicts the uniform distribution of nanoparticles (10 nm in size) on solid oxide electrochemical cell electrode surface. The tested Pt, Pd, Au and Co nanoparticles are shown in different colours.

See Jung et al.

The integration of condensed matter qubits towards a synchronous control and read-out for quantum computational applications requires 2D arrays of qubits with control lines above and below the qubit layer. For single atom qubits in silicon, dopants must be patterned in separate atomic layers of the crystalline silicon with high precision and without diffusion in between layers. By means of scanning tunnelling microscope lithography, Koch et al. have now patterned a phosphorous-dopant qubit in a vertically gated single electron transistor with interlayer alignment accuracy better than 5 nm. The cover art shows the all-crystalline structure with the bright atomic qubit in the centre being controlled by red in-plane control lines and a cyan top gate.

See Koch et al.

Complete removal of cancer tissue during surgery is hard to achieve and frequently results in tumour recurrence. While radiotherapy and chemotherapy can help to prevent cancer recurrence, they cause severe toxic effects, prompting the search for alternative approaches, such as immunotherapy, to curb tumour spread. Now, Chen and co-workers present an immunotherapy gel that forms upon the reaction of two components: a fibrinogen solution containing CaCO3 nanoparticles that encapsulate anti-CD47 antibodies, and a thrombin solution. Once sprayed on the surgical wound, the two components react, forming a fibrin gel in situ. Upon acidic degradation, the CaCO3 nanoparticles activate the tumour suppressing macrophages and release the anti-CD47 antibodies, which block the ‘don’t eat me’ ligands on cancer cells, making them susceptible to macrophage recognition and elimination. By reprogramming the tumour microenvironment, the gel prevents local tumour recurrence and distant tumour formation. The image on the cover is a false-coloured cryo-SEM image of the fibrin gel loaded with the bioresponsive nanoparticles.

See Gu et al.