The biointerface established by vertical nanoprobes—arrays of vertical high-aspect-ratio nanostructures—is a simple, controllable and powerful tool for interrogating and manipulating cells. The cover shows a colored electron microscopy image of a single cell on nanoneedles. See Roey Elnathan et al.

In this Focus Issue we explore the different facets of wearable electronics, from the design of wearable sensors and of self-charging power sources, to the use of wearable electronics for deep-tissue monitoring and for collecting signals from the mucosa. The cover artistically illustrates the use of wearable sensors in daily life and for medical purposes. See the Editorial.

Halide perovskite light emitters hold promise for next-generation high-colour-purity displays and lighting applications. The cover artistically illustrates the crystal structure of a perovskite lattice and its versatile colour tuning, with the shadow-like colourful triangle representing the wide colour gamut generated by the perovskite. See Han et al.

Architected materials are structured at the intermediate scale between the atomic and bulk scale, and they can be encoded with a temporal degree of freedom such that they evolve over time, resulting in unique materials properties and functionalities. The cover artistically illustrates three examples of responsive architected materials. See Xia et al.

Multicaloric cooling promises environmentally friendly and high-efficiency refrigeration. This cover artistically illustrates magnetic and electric fields and pressure acting together to cool a multicaloric material. See Huilong Hou et al.

Defects have a key role in determining the functionality of solids and can make them powerful catalysts. In particular, defect chemistry in metal oxides is important to enable photoelectrochemical reactions. This cover artistically illustrates an artificial leaf performing photosynthesis. See Ernest Pastor et al.

Trained immunity is a form of nonspecific immune memory harboured within the innate immune system, and nanomaterials are ideal platforms with which to regulate it. This cover shows a selection of SEM images of nanoparticles in the bone marrow. See Mandy van Leent et al.

Centrifugal and shear forces induced by rotary motion can alter chemical reactivity, materials synthesis and self-organization behavior, enabling new types of chemical experimentation. The cover image is a photograph of a spinning multiphase reactor. See Bartosz Grzybowski et al.

Spin–orbit coupling can be leveraged to enable new functional properties in oxide materials, in particular for spintronics applications. The cover image is an artistic impression of spin-charge conversion in a Rashba two-dimensional electron gas. See Felix Trier et al.

Solution-processed networks of 2D materials are promising for applications in printed electronics, but more research is needed to understand how they are electrically limited by the junctions between nanosheets and their macroscopic electrical properties. The cover image is an artistic illustration showing electrons flowing from a gold electrode across a nanosheet network. See Adam Kelly et al.

Plastics shape the modern world, but between their reliance on fossil fuels and their massive accumulation as waste, plastics are also at the heart of a dual environmental crisis. In this month’s Focus Issue, our collection of articles explores plastics from many perspectives, including biopolymers for a circular economy, the design of polymers with end-of-life management in mind and the issue of microplastics. See Plastics give and plastics take.

The fate of implanted biomaterials and biomedical devices can be investigated by intravital microscopy in animal models to reveal regenerative and potentially pathological responses to the implant, such as the foreign body response. The cover image shows a three-dimensional reconstruction of a polycaprolactone electrospun scaffold, capturing second-harmonic generation and third-harmonic generation by nonlinear multiphoton microscopy. See Eleonora Dondossola & Peter Friedl.