http://onlinelibrary.wiley.com/rss/journal/10.1002/(ISSN)1521-4095

Water-free LiYb0.9Gd0.1F4 represents prominent −ΔS m values among the representative sub-Kelvin-temperature refrigerants throughout the whole temperature range from 0.1 to 1 K, demonstrating an exceptional specific cooling capacity of 46.943 mJ cm−3 T−1 at 300 mK in a self-built two-stage adiabatic demagnetization refrigerator.

Adiabatic demagnetization refrigeration, which utilizes the magnetocaloric effect of magnetic refrigerants, stands as the sole cooling technology capable of achieving sub-Kelvin temperatures efficiently and reliably without relying on scarce 3He resources or gravity. However, current sub-Kelvin magnetic refrigerants encounter challenges such as structural instability in vacuum or under mild heating, along with small magnetic entropy change (−ΔS m) values, which significantly limit their practical applications. Here a water-free magnetic refrigerant, LiGd0.1Yb0.9F4 is reported, prepared by introducing Li⁺ ions to reduce the dipolar interactions between Gd3+ ions and/or Yb3+ ions. Notably, this refrigerant possesses a magnetic ordering temperature of 85 mK, while its experimental −ΔS m reaches up to 136 mJ cm−3 K−1 (0.68 K and 2 T), more than three times the theoretical value of CrK(SO4)2·12H2O. Significantly, this refrigerant not only cools the test sample to temperatures as low as 160 mK but also achieves a specific cooling capacity of 46.943 mJ cm−3 T−1 at 300 mK. Remarkably, the specific cooling capacity at 300 mK is more than double that of commercial CrK(SO4)2·12H2O, representing one of the most notable values reported among all known magnetic refrigerants operating at sub-Kelvin temperatures.

The ‘Instant FLISA’ (fluorophore-linked immunosorbent assay) biosensor enables rapid quantification of protein biomarkers at picomolar concentrations within 15 min in undiluted serum and plasma. This is achieved with the ‘monolithic dual-antibody clamp’ reagent that tightly binds to the target molecule and produces a fluorescence signal which is detected with an optical fiber probe.

For more than fifty years, the enzyme-linked immunosorbent assay (ELISA) serves as the gold standard for protein biomarker detection. However, conventional ELISA requires considerable sample preparation including reagent addition, incubation, and washing steps, limiting its usefulness at the point-of-care. In this work, the “instant ELISA” (fluorophore-linked immunosorbent assay) biosensor that can measure protein biomarkers in the picomolar range within 15 min in undiluted plasma or serum with no sample preparation is described. The sensor leverages a synthetic reagent termed the “monolithic dual-antibody clamp” (MDAC) which preserves the specificity, sensitivity, and generalizability of an ELISA, but produces a fluorescence signal as two surface-tethered antibodies form a “sandwich” by binding to two distinct epitopes on the target. As exemplars, picomolar quantification of tumor necrosis factor alpha (TNFα) and monocyte chemotactic protein (MCP)-1, the latter of which is a useful prognostic indicator of cytokine release syndrome in patient plasma samples during chimeric antigen receptor T cell therapy are demonstrated.

A universal method for synthesizing nanostructured transition metal oxides (NTMOs) through induced solidification of microdroplets enables rapid production in air within a minute. This method allows precise control of alignment for various applications, including gas sensors and PUFs, and supports doping, reduction, and chalcogenization while preserving morphology.

Nanostructured transition metal oxides (NTMOs) have consistently piqued scientific interest for several decades due to their remarkable versatility across various fields. More recently, they have gained significant attention as materials employed for energy storage/harvesting devices as well as electronic devices. However, mass production of high-quality NTMOs in a well-controlled manner still remains challenging. Here, a universal, ultrafast, and solvent-free method is presented for producing highly crystalline NTMOs directly onto target substrates. The findings reveal that the growth mechanism involves the solidification of condensed liquid-phase TMO microdroplets onto the substrate under an oxygen-rich ambient condition. This enables a continuous process under ambient air conditions, allowing for processing within just a few tens of seconds per sample. Finally, it is confirmed that the method can be extended to the synthesis of various NTMOs and their related compounds.

This study reveals the concentration-dependent self-assembly of conjugated polymers, uncovering lyotropic liquid crystalline phases in several donor polymers. The extent of this self-assembly process, determined by the solvent drying dynamics during blade coating, gives distinct film morphologies that significantly impact the device efficiency and stability, offering a framework for optimizing performance through precise control of coating conditions and polymer assembly.

Conjugated polymers can undergo complex, concentration-dependent self-assembly during solution processing, yet little is known about its impact on film morphology and device performance of organic solar cells. Herein, lyotropic liquid crystal (LLC) mediated assembly across multiple conjugated polymers is reported, which generally gives rise to improved device performance of blade-coated non-fullerene bulk heterojunction solar cells. Using D18 as a model system, the formation mechanism of LLC is unveiled employing solution X-ray scattering and microscopic imaging tools: D18 first aggregates into semicrystalline nanofibers, then assemble into achiral nematic LLC which goes through symmetry breaking to yield a chiral twist-bent LLC. The assembly pathway is driven by increasing solution concentration – a common driving force during evaporative assembly relevant to scalable manufacturing. This assembly pathway can be largely modulated by coating regimes to give 1) lyotropic liquid crystalline assembly in the evaporation regime and 2) random fiber aggregation pathway in the Landau–Levich regime. The chiral liquid crystalline assembly pathway resulted in films with crystallinity 2.63 times that of films from the random fiber aggregation pathway, significantly enhancing the T80 lifetime by 50-fold. The generality of LLC-mediated assembly and enhanced device performance is further validated using polythiophene and quinoxaline-based donor polymers.

Inspired by marine sponges, the E7 peptide and EXOs-functionalized “Cell Climbing Frame” with a hierarchical porous structure specifically recruits and rejuvenates autologous BMSCs, and enhances cellular proliferation and osteogenic differentiation by down-regulating senescent-related genes and decreasing SASP factor release, thereby promoting the repair of osteoporotic bone defects and achieving robust multi-stage osseointegration.

Osteoporosis, characterized by low bone mass and high fracture risk, challenges orthopedic implant design. Conventional 3D-printed Ti6Al4V scaffolds are mechanically robust but suffer from poor bone regeneration in osteoporotic patients due to stress shielding and cellular senescence. In this study, a functionalized 3D-printed Ti6Al4V “Cell Climbing Frame” is developed, aiming to adapt to the mechanical microenvironment of osteoporosis, effectively recruit and support the adhesion and growth of autologous bone marrow mesenchymal stem cells (BMSCs), while rejuvenating senescent cells for improved bone regeneration. Inspired by marine sponges, the processing accuracy limitations of selective laser melting (SLM) technology is broke through innovatively constructing a hierarchical porous structure with macropores and micropores nested within each other. Results demonstrate that the unique hierarchical porous scaffold reduces the elastic modulus, facilitates blood penetration, and enhances cell adhesion and growth. Further surface functionalization with E7 peptides and exosomes promotes the attraction and rejuvenation of BMSCs and boosts migration, proliferation, and osteogenic differentiation in vitro. In vivo, the functionalized “Cell Climbing Frame” accelerates bone repair in osteoporotic rats, while delaying surrounding bone loss, enabling robust multi-stage osseointegration. This innovation advances 3D-printed regenerative implants for osteoporotic bone repair.

Traditional aqueous electrolytes are limited by water's decomposition voltage (≈1.23 V). “Water-in-Salt” (WIS) electrolytes expand this stability window to 3 V, revolutionizing aqueous battery research. This review discusses the solvation structures, ion transport mechanisms, and interfacial properties of WIS electrolytes, highlighting advancements and future directions in aqueous electrolyte design.

Traditional aqueous electrolytes have a limited electrochemical stability window due to the decomposition voltage of water (≈1.23 V). “Water-in-Salt” (WIS) electrolytes are developed, which expand the stability window of aqueous electrolytes from 1.23 to 3 V and sparked a global surge of research in aqueous batteries. This breakthrough revealed novel aspects of solvation structure, ion transport mechanisms, and interfacial properties in WIS electrolytes, marking the start of a new era in solution chemistry that extends beyond traditional dilute electrolytes and has implications across electrolyte research. In this review, the current mechanistic understanding of WIS electrolytes and their derivative designs, focusing on the construction of solvation structures is presented. The insights gained and limitations encountered in bulk solvation structure engineering is further discussed. Finally, future directions beyond WIS for advancing aqueous electrolyte design is proposed.

This work reveals the insight reason for the Li+ and Na+ storage performance of the rutile phase, which is determined by the electrochemically driven formed rocksalt nanograins. Importantly, the electrochemically in situ formed rocksalt phase has open diffusion channels for rapid Li+ or Na+ (de)intercalations through a solid-solution mechanism, which determines the pseudocapacitive, “mirror-like” cyclic voltammetry curves and excellent rate capabilities.

Rutile titanium dioxide (TiO2(R)) lacks octahedral vacancies, which is not suitable for Li+ and Na+ intercalation via reversible two-phase transformations, but it displays promising electrochemical properties. The origins of these electrochemical performances remain largely unclear. Herein, the Li+ and Na+ storage mechanisms of TiO2(R) with grain sizes ranging from 10 to 100 nm are systematically investigated. Through revealing the electrochemically-driven atom rearrangements, nanosize effect and kinetics analysis of TiO2(R) nanograins during repeated cycling with Li+ or Na+, a unified mechanism of electrochemically-driven multistep rutile-to-rocksalt phase transformations is demonstrated. Importantly, the electrochemically in situ formed rocksalt phase has open diffusion channels for rapid Li+ or Na+ (de)intercalation through a solid-solution mechanism, which determines the pseudocapacitive, “mirror-like” cyclic voltammetry curves and excellent rate capabilities. Whereas, the nanosize effect determines the different Li+ and Na+ storage capacities because of their distinct reaction depths. Remarkably, the TiO2(R)-10 nm anode in situ turns into rocksalt nanograins after 30 cycles with Na+, which delivers a reversible capacity of ≈200 mAh g−1, high-rate capability of 97 mAh g−1 at 10 A g−1 and long-term cycling stability over 3000 cycles. The findings provide deep insights into the in situ phase evolutions with boosted electrochemical Li+ or Na+ storage performance.

Soft-actuated cuff electrodes (SACE) for bidirectional peripheral interfaces enable minimal and secure contact to the nerve through fluid injection-based soft actuation. A 3D bent structure can grasp and securely contact the nerves with only a little pressure (<1.21 gram-force). The SACE can achieve negligible damage to the nerve during recording of sensory and motor feedback signals with superior SNR and neuromodulation for long-term studies.

Neural interfaces with embedded electrical functions, such as cuff electrodes, are essential for monitoring and stimulating peripheral nerves. Still, several challenges remain with cuff electrodes because sutured devices can damage the nerve by high pressure and the secured contact of electrodes with the nerve is hard to accomplish, which however is essential in maintaining electrical performance. Here, a sutureless soft-actuated cuff electrodes (SACE) that can envelop the nerve conveniently by creating a bent shape controlled upon fluid injection, is introduced. Moreover, fluid injection protrudes part of the device where electrodes are formed, thereby achieving minimized, soft but secure contact between the electrodes and the nerve. In vivo results demonstrate the successful recording and stimulation of peripheral nerves over time up to 6 weeks. While securing contact with the nerve, the implanted electrodes can preserve the nerve intact with no reduction in blood flow, thereby indicating only minimal compressive force applied to the nerve. The SACE is expected to be a promising tool for recording and stimulation of peripheral nerves toward bidirectional neuroprostheses.

A novel UV-induced two-step thiol-ene “click chemistry” is introduced for the tailorable fluorescent perovskite quantum dots (T-PQDs). A protective shell is formed around the PQDs in the first step, while chemical cross-linking between PQD and thiol-ene polymer occurs in the second step. The T-PQDs offer high efficiency, stability, and processability, facilitating their multiform manufacturing for a wide range of applications.

In practical applications, fluorescent perovskite quantum dots (PQDs) must exhibit high efficiency, stability, and processibility. So far, it remains a challenge to synthesize PQDs with stable dispersibility in tailorable monomers both before and after photocuring. In this work, a novel strategy of UV-induced two-step thiol-ene “click chemistry” is proposed to prepare PQDs with these attributes. The first step aims to epitaxially grow a shell around the PQD core to ensure stable dispersibility in a thiol-ene monomer solution. The second step is to achieve stable dispersibility in the photocured thiol-ene matrixes for multiform manufacturing processes. The tailorable PQDs (T-PQDs) not only have the highest photoluminescence quantum yield (PLQY) to ≈100% for green emission and over 96% for red emission, but also exhibit remarkable stability under severe conditions, including “double 85” aging, water exposure, and mechanical stress. Moreover, their exceptional processability allows for various processing techniques, including slot-die coating, inkjet printing, direct-laser writing, UV-light 3D printing, nanoimprinting, and spin coating. The high efficiency and stability of T-PQDs facilitate their multiform manufacturing for a wide range of applications.

In this study, bi-confinement effects arising from a highly cross-linked polymer network and rigid Al₂O₃ matrix are exploited to achieve ultra-stable carbonized polymer dots (CPDs). The obtained CPDs@Al2O3 composite demonstrates exceptional long-term stability in various solvents and high photoluminescence emission thermotolerance up to 500 K for 150 h, representing the best performance of carbon dots under harsh conditions reported to date.

Carbon dots are emerging luminescent nanomaterials that have drawn considerable attention due to their abundance, environmental friendliness, and customizable optical properties. However, their susceptibility to temperature-induced vibrational exciton changes and the tendency to thermal quenching of emission have hindered their practical applications. Here, a method is reported for achieving high-temperature photoluminescence carbonized polymer dots (CPDs) through a bi-confinement approach that involves a highly cross-linked polymer network and a rigid Al2O3 matrix. As the temperature increased from 303 to 500 K, the fluorescence and phosphorescence emission intensities of CPDs@Al2O3 remained virtually unchanged, with the emission duration exceeding 150 h at 500 K. Additionally, CPDs@Al2O3 composites with different degrees of carbonization exhibit dynamic excitation-dependent photoluminescence properties, which can be patterned for multiple information encryption application. This work provides a concept for designing stable and luminous CPDs under harsh conditions, thus expanding their potential application range.

A stretchable multimodal photonic sensor capable of simultaneously detecting and discriminating strain deformations, temperature, and sweat pH is developed for on-skin health monitoring. By integrating multiple sensing mechanisms in a single hydrogel-coated PDMS optical fiber (HPOF) at distinct wavelengths, the device achieves simultaneous monitoring of heartbeat, respiration, body temperature, and sweat pH of a person in real-time with negligible crosstalk.

Stretchable sensors that can conformally interface with the skins for wearable and real-time monitoring of skin deformations, temperature, and sweat biomarkers offer critical insights for early disease prediction and diagnosis. Integration of multiple modalities in a single stretchable sensor to simultaneously detect these stimuli would provide a more comprehensive understanding of human physiology, which, however, has yet to be achieved. Here, this work reports, for the first time, a stretchable multimodal photonic sensor capable of simultaneously detecting and discriminating strain deformations, temperature, and sweat pH. The multimodal sensing abilities are enabled by realization of multiple sensing mechanisms in a hydrogel-coated polydimethylsiloxane (PDMS) optical fiber (HPOF), featured with high flexibility, stretchability, and biocompatibility. The integrated mechanisms are designed to operate at distinct wavelengths to facilitate stimuli decoupling and employ a ratiometric detection strategy for improved robustness and accuracy. To simplify sensor interrogation, spectrally-resolved multiband emissions are generated upon the excitation of a single-wavelength laser, utilizing upconversion luminescence (UCL) and radiative energy transfer (RET) processes. As proof of concept, this work demonstrates the feasibility of simultaneous monitoring of the heartbeat, respiration, body temperature, and sweat pH of a person in real-time, with only a single sensor.

Wetting-Induced Process

The wetting-induced interconnected reentrant geometry (WING) process enables the large-scale fabrication of multifunctional re-entrant microcavity surfaces, representing a significant technological advancement. Utilizing capillary action in a scalable roll-to-roll printing technique, it produces surfaces with exceptional liquid repellency while maintaining microstructures under external forces. This process offers a cost-effective and high throughput solution for various applications, such as anti-icing, anti-fouling, and particle capture. More details can be found in article number 2411064 by Seok Kim, Young Tae Cho, and co-workers.

Recyclable Polyimide Composite Aerogels

In article number 2411599 by Wim J. Malfait, Qinghua Zhang, Shanyu Zhao, and co-workers, a molecular design strategy was employed to facilitate the formation and controlled disassembly of high-performance, recyclable polyimide composite aerogels. The innovative “aerogel-in”aerogel" structure exhibits a highly porous, interpenetrating architecture with complete disaggregation capabilities. This composite showcases exceptional resistance to extreme conditions, spanning from ultra-low temperatures of −196 °C to ultra-high environments of 800 °C, providing a groundbreaking and sustainable solution for next-generation thermal protection materials.

Single-Cell Exosome

The background shows a microwell array chip with a light beam symbolizing photothermal technology for single-cell isolation. A magnified view highlights exosome secretion by a purple cell. Multicolored markers identify different exosomes. More details can be found in article number 2411259 by Lin Han and co-workers.

Polymorphing Hydrogels – Sculpting with Light

Polymorphing hydrogels can be reshaped on demand by shining light on specific areas. These hydrogels incorporate photo-reactive DNA cross-links, whose lengths are reversibly controlled by UV or visible light. Under UV illumination, the cross-links shorten, causing the hydrogel to contract, while exposure to visible light restores their original length. The image symbolizes this process by depicting a “VIS”ible man and “UV”men working together to sculpt the material. More details can be found in article number 2414648 by Eunjin Choi, Yeongjae Choi, and co-workers.

Perovskite Quantum Dots

Inspired by the hedgehog, the fluorescent perovskite quantum dots (PQDs) with a defending layer are designed via using thiol-ene “click chemistry”. Benefiting from the high colloidal dispersion of PQDs in the photo-curable matrixes, the PQDs offer high efficiency, stability, and processability, facilitating their multiform manufacturing for a wide range of applications, even for underwater displays. More details can be found in article number 2411453 by Zuliang Du and co-workers.

Organic Electronics

Record ion mobility and conductivities are revealed within a nanoscopic interfacial superhighway of an organic mixed ionic-electronic conductor. Fast ion transport can be controlled by hydrophobicity of molecules local to this channel, effectively gating ion access to the superhighway. This mechanism is used in a novel chemical sensing device which detects the dynamics of a local, buried chemical reaction. More details can be found in article number 2406281 by Tamanna Khan, Terry McAfee, Thomas J. Ferron, Awwad Alotaibi, and Brian A. Collins.

Soft-Actuated Cuff Electrodes

A sutureless, soft-actuated cuff electrodes (SACE) device envelops a nerve by itself upon fluid injection into part of the device made of soft and expandable polymeric structures. Three-dimensionally protruded part of the device ensures soft, minimal but secure contact between electrodes and nerve, resulting in superior performance in signal recording. More details can be found in article number 2409942 by Sohee Kim and co-workers.

This review examines the critical role of multi-scale hierarchical structures, from molecular to macro levels, in optimizing light harvesting and photothermal efficiency in solar steam generation (SSG) systems. By tailoring materials and structures to enhance light absorption, manage thermal properties, and support effective water transport, these integrated designs advance solar-thermal desalination as a sustainable solution to water scarcity.

Solar steam generation (SSG) presents a promising approach to addressing the global water crisis. Central to SSG is solar photothermal conversion that requires efficient light harvesting and management. Hierarchical structures with multi-scale light management are therefore crucial for SSG. At the molecular and sub-nanoscale levels, materials are fine-tuned for broadband light absorption. Advancing to the nano- and microscale, structures are tailored to enhance light harvesting through internal reflections, scattering, and diverse confinement effects. At the macroscopic level, light capture is optimized through rationally designed device geometries, configurations, and arrangements of solar absorber materials. While the performance of SSG relies on various factors including heat transport, physicochemical interactions at the water/air and material/water interfaces, salt dynamics, etc., efficient light capture and utilization holds a predominant role because sunlight is the sole energy source. This review focuses on the critical, yet often underestimated, role of hierarchical light harvesting/management at different dimensional scales in SSG. By correlating light management with the structure-property relationships, the recent advances in SSG are discussed, shedding light on the current challenges and possible future trends and opportunities in this domain.