Jing Zhang

The mechanical, ionic, and environmental stability of various 2D perovskite ligands is reported. It is shown that the best balance of mechanical robustness, environmental stability, ion activation energy, and reduced mobile ion concentration under accelerated aging is achieved with the usage of 4TmI, a quater-thiophene-based organic cation that forms an organic-semiconductor-incorporated perovskite structure.

Abstract

Hybrid metal halide perovskite (MHP) materials, while being promising for photovoltaic technology, also encounter challenges related to material stability. Combining 2D MHPs with 3D MHPs offers a viable solution, yet there is a gap in the understanding of the stability among various 2D materials. The mechanical, ionic, and environmental stability of various 2D MHP ligands are reported, and an improvement with the use of a quater-thiophene-based organic cation (4TmI) that forms an organic-semiconductor incorporated MHP structure is demonstrated. It is shown that the best balance of mechanical robustness, environmental stability, ion activation energy, and reduced mobile ion concentration under accelerated aging is achieved with the usage of 4TmI. It is believed that by addressing mechanical and ion-based degradation modes using this built-in barrier concept with a material system that also shows improvements in charge extraction and device performance, MHP solar devices can be designed for both reliability and efficiency.

This review offers a comprehensive overview of the advancements in 2D materials synthesis by salt-assisted methods, including molten salt method (MSM), salt-assisted chemical vapor deposition (SA-CVD), and salt-template method (STM). It highlights the advantages, underlying mechanisms, and recent innovations of these methods. Challenges and future directions are also discussed, emphasizing salt-assisted strategies to produce high-quality 2D materials.

Abstract

Two-dimensional (2D) materials have been attracting extensive interest due to their remarkable chemical, optical, electrical, and magnetic properties, making them ideal candidates for a broad range of applications. Developing facile synthesis methods that can fabricate high-quality 2D materials in an efficient, scalable, and cost-effective way is essential. Among the emerging techniques, salt-assisted methods to synthesize 2D materials, including molten salt method, salt-assisted chemical vapor deposition, and salt-template method, has demonstrated significant potential in fulfilling these requirements. This review highlights recent advancements in the synthesis of 2D materials through salt-assisted methods, focusing on their preparation processes and wide-ranging applications. It also explores the role of salts, in various forms, in directing the formation of 2D structures, providing insights for strategic synthesis design. Finally, challenges and future directions in salt-assisted synthesis are discussed, emphasizing strategies to enable controllable, high-yield production of 2D materials.

The second near-infrared window (NIR-II) fluorescence imaging offers superior spatiotemporal resolution and deep tissue penetration. Organic small-molecule fluorophores are promising for clinical use but often suffer from background noise. Developing activatable NIR-II fluorophores is essential for accurate disease detection and advancing clinical applications, as this review highlights key strategies and progress.

Abstract

The second near-infrared window (NIR-II) fluorescence imaging has been widely adopted in basic scientific research and preclinical applications due to its exceptional spatiotemporal resolution and deep tissue penetration. Among the various fluorescent agents, organic small-molecule fluorophores are considered the most promising candidates for clinical translation, owing to their well-defined chemical structures, tunable optical properties, and excellent biocompatibility. However, many currently available NIR-II fluorophores exhibit an “always-on” fluorescence signal, which leads to background noise and compromises diagnostic accuracy during disease detection. Developing NIR-II activatable organic small-molecule fluorescent probes (AOSFPs) for accurately reporting pathological changes is key to advancing NIR-II fluorescence imaging toward clinical application. This review summarizes the rational design strategies for NIR-II AOSFPs based on four core structures (cyanine, hemicyanine, xanthene, and BODIPY). These NIR-II AOSFPs hold substantial potential for clinical translation. Furthermore, the recent advances in NIR-II AOSFPs for NIR-II bioimaging are comprehensively reviewed, offering clear guidance and direction for their further development. Finally, the prospective efforts to advance NIR-II AOSFPs for clinical applications are outlined.

Nature, Published online: 19 December 2024; doi:10.1038/s41586-024-08525-3

Signatures of ambient pressure superconductivity in thin film La₃Ni₂O₇

Highly Refractive Transparent Half-Heuslers for Near-Infrared Optics

Advanced control of light focusing, reflection, and transmission is possible by using highly refractive transparent materials. In article number 2402295, Akihiro Ishii, Hitoshi Takamura, and co-workers report the discovery of 22 ternary half-Heuslers that exhibit higher refractive indices with wider band gaps than conventional high-refractive-index transparent materials in the near-infrared region. Material design strategies for achieving a high index and wide gap are also explained.

Optimized Er-Doped LiNbO₃ Quantum Memory Platform

In the study by Andrej Kuznetsov, Kiwon Moon, and co-workers (see article number 2401374), an optimized approach for fabricating an efficient solid-state photonic quantum memory platform is proposed. This approach relies on dynamic defect annealing occurring in the LiNbO₃ matrix material during its implantation with Er ions at elevated temperatures. The resulting platform, with minimized crystalline disorder and enhanced optical activity, is promising for realizing robust quantum memory with extended storage times and high efficiencies.

Collagen-mimicking polypeptides (CMPs) which are recombinantly expressed in E. coli with site-specifically incorporated L-3,4-dihydroxyphenylalanine (L-DOPA) using genetic code expansion, exhibit enhanced structural stability, fibrillation, and biocompatibility. These CMPs self-assemble into collagen fibrils, supporting human fibroblast adhesion and growth in 2-D and 3-D scaffolds.

Abstract

Collagen, a key structural protein in the extracellular matrix (ECM), provides essential physical and biological support for cells, making it indispensable in tissue engineering (TE). Producing collagen-mimicking polypeptides (CMPs) in E. coli offers advantages such as rapid production, cost efficiency, and ease of genetic modifications. These CMPs can self-assemble into collagen fibrils, although they lack the post-translational modifications (PTMs) required for structural stability. To address this, the described E. coli system employs genetic code expansion to incorporate L-3,4-dihydroxyphenylalanine (L-DOPA) into CMPs at specific sites. The catechol side chain of L-DOPA enhances molecular structural stability, supports cellular attachment, and promotes cell growth. These CMPs form a triple-helix structure and self-assemble in vitro to construct collagen fibrils, with the inclusion of L-DOPA significantly enhancing the fibrillation process. The CMPs are biocompatible, enabling the spreading and increased metabolic activity of human fibroblasts cultured on 2-D hydrogels or within 3-D scaffolds, contingent on the presence of L-DOPA-incorporated CMPs. This system allows for precise genetic modifications, incorporating non-canonical amino acids to customize CMP properties for diverse TE applications. This innovative strategy merges TE and synthetic biology to improve collagen-based biomaterials, providing custom-made solutions.

Based on photothermal materials, such as a detachable assembly layer, laser direct-writing (LDW) programmable dynamic aligned wrinkling is realized on arbitrary films and even on arbitrary film/substrate systems. Theoretical modeling reveals that LDW-induced localized anisotropic stress field answers for the LDW path-parallel wrinkling orientation. This dynamic oriented wrinkling has broad applications in soft photonics.

Abstract

Dynamic oriented wrinkling especially on arbitrary film materials is highly desirable yet remains a great challenge. Here, fabrication of programmable aligned wrinkling patterns on different film/substrate systems via a laser-direct-writing (LDW) method is reported, regardless of photofunctionality and transparence of the target films. The key is related to smart introduction of photothermal materials (PTMs) into compliant substrates and even as an independent attachable/detachable layer assembled underneath the film/substrate systems. Experiments and theoretical modeling reveal that with the help of the photothermal effect of PTMs, in situ LDW-induced localized dynamic anisotropic stress field is responsible for the intriguing LDW path-parallel aligned wrinkling. Furthermore, dimensional analysis is carried out and explicit solutions quantifying the connection of wrinkling morphology parameters with the LDW conditions are derived for the first time, which enables theoretical pattern designing. It is highlighted that the attachable/detachable assembly strategy for the independent PTMs layer endows arbitrary film/substrate systems with on-demand photosensitivity when needed, which has been inaccessible previously. As demonstrated, these dynamic oriented wrinkling systems have found broad applications especially in smart soft photonics, e.g., information storage, anticounterfeiting, and responsive optical devices.

2D vdW α-In₂Se₃ is used as a ferroelectric tunneling junction in a planar structure with Au electrodes. The interface between the α-In₂Se₃ semiconductor and the Au electrode is studied to achieve a large on/off ratio by inserting a SiO₂ insulating barrier. The polarization of α-In₂Se₃ gradually changes with the applied pulses, mimicking synaptic properties and exhibiting linear LTP/LTD behavior.

Abstract

A synaptic memristor using 2D ferroelectric junctions is a promising candidate for future neuromorphic computing with ultra-low power consumption, parallel computing, and adaptive scalable computing technologies. However, its utilization is restricted due to the limited operational voltage memory window and low on/off current (I_ON/OFF) ratio of the memristor devices. Here, it is demonstrated that synaptic operations of 2D In₂Se₃ ferroelectric junctions in a planar memristor architecture can reach a voltage memory window as high as 16 V (±8 V) and I_ON/OFF ratio of 10⁸, significantly higher than the current literature values. The power consumption is 10⁻⁵ W at the on state, demonstrating low power usage while maintaining a large I_ON/OFF ratio of 10⁸ compared to other ferroelectric devices. Moreover, the developed ferroelectric junction mimicked synaptic plasticity through pulses in the pre-synapse. The nonlinearity factors are obtained 1.25 for LTP, −0.25 for LTD, respectively. The single-layer perceptron (SLP) and convolutional neural network (CNN) on-chip training results in an accuracy of up to 90%, compared to the 91% in an ideal synapse device. Furthermore, the incorporation of a 3 nm thick SiO₂ interface between the α-In₂Se₃ and the Au electrode resulted in ultrahigh performance among other 2D ferroelectric junction devices to date.

Topological supercoupling phenomenon is demonstrated for the first time, enabling efficient waveguide coupling over separation distances ranging from sub-wavelength to multiple wavelengths, driven by the valley vortex wave in the topological valley Hall system. This approach aims at integrating increasing number of on-chip components to further enhance the chip compactness and density.

Abstract

Waveguide interconnect coupling control is essential for enhancing the chip density of photonic integrated circuits to incorporate a growing number of components. However, a critical engineering challenge is to achieve both strong waveguide isolation and efficient long-range coupling on a single chip. Here, a novel photonic supercoupling phenomenon is demonstrated for waveguide coupling over separation distances from a quarter to five wavelengths (λ), leveraging the tunable mode tails and the vortex energy flow in topological valley Hall system. A supercoupled integrated chip is developed, realizing a 91% coupling ratio and a −30 dB isolation over 2.8λ waveguide separations simultaneously. Supercoupled devices are further showcased including a waveguide-cavity system with 3.2λ excitation distance, and a waveguide directional supercoupler with a compact coupling area of nearly λ²/4, which outperform conventional devices. Supercoupling provides new degrees of freedom for optimizing coupling and isolation between photonic integrated components, facilitating new applications in on-chip sensing, lasing, and telecommunications.

Controlling exciton resonances in twodimensional materials can create dynamic flat optics

Ising superconductors are known for remarkable resilience to external in-plane magnetic fields (B _∥) due to the protection of strong spin-orbit coupling fields α_SOC. By forming Cooper pairing states in mirror-symmetric Fermi surfaces with highly anisotropic α_SOC, a new type-III Ising superconductivity is discovered in atomically-thin natural van der Waals heterostructures of TaSe₂/SnSe with anomalous B _∥-enhanced T _c .

Abstract

Van der Waals (vdW) crystals with strong spin-orbit coupling (SOC) provide great opportunities for exploring unconventional 2D superconductors, wherein new pairing states emerge due to the interplay of SOC with crystalline symmetries, electronic correlations, quenched disorders and external modulation forces, etc. Here, a distinct mirror-symmetry protected Ising pairing state with unprecedented Γ- and M-valley symmetries in natural vdW heterostructures (vdWH) of interweaving tetragonal SnSe and trigonal 1H-TaSe₂ monolayers is reported, in which the unidirectional lattice interlocking effectively suppresses the K-valley Ising pairing mechanism by incommensurate charge-density-wave (CDW) transitions. In the 2D limit of an TaSe₂/SnSe bilayer with intact basal mirror symmetry (M _z ), the mirror-symmetric vdWH Ising superconductors show anomalous in-plane magnetic field B _‖-controlled enhancements in the critical temperature T _c, which is completely absent for multilayer vdWHs with broken M _z induced by orthorhombic stacking between nearest-neighbour TaSe₂ monolayers. The experimental observations consistently reveal a mirror symmetry-protected type-III Ising state in the inversion asymmetric lattice of 1H-TaSe₂, which is predicted to be a mixture of spin-singlet and spin-triplet states.

A biodegradable, robust, and versatile PUF platform with multi-mode encoding, multi-level cryptographic keys, and multiple authentication operations is developed by imprinting chaotically grown calcites on a versatile protein film. This all-biomaterial-based PUF exhibits superior encoding diversity, eco-friendly manufacturing, authentication ease, stability, and versatility over existing biocompatible PUF labels, providing a practical, high-security solution for combating counterfeiting across various applications.

Abstract

Physical unclonable functions (PUFs) are emerging as a cutting-edge technology for enhancing information security by providing robust security authentication and non-reproducible cryptographic keys. Incorporating renewable and biocompatible materials into PUFs ensures safety for handling, compatibility with biological systems, and reduced environmental impact. However, existing PUF platforms struggle to balance high encoding capacity, diversified encryption signatures, and versatile functionalities with sustainability and biocompatibility. Here, all-biomaterial-based unclonable anti-counterfeiting labels featuring multi-mode encoding, multi-level cryptographic keys, and multiple authentication operations are developed by imprinting biomimetic-grown calcites on versatile silk protein films. In this label, the inherent non-clonability comes from the randomized characteristics of calcites, mediated by silk protein during crystal growth. The successful embedding of photoluminescent molecules into calcite lattices, assisted by silk protein, allows the resulting platform to utilize fluorescence patterns alongside birefringence for high-capacity encoding. This design facilitates easy and rapid authentication through Hamming distance and convolutional neural networks using standard cameras and portable microscopes. Moreover, angle-dependent polarization patterns enable multi-level key generation, while multi-spectral fluorescence signals offer multi-channel keys. The developed anti-counterfeiting labels combine biodegradability, green manufacture, easy authentication, high-level complexity, low cost, robustness, patternability, and versatility, offering a practical and high-security solution to combat counterfeiting across various applications.

The study explores the effect of chromium oxychloride (CrOCl) spin states on bilayer graphene (BLG) using capacitance measurements. A unique hysteretic behavior in charging states is observed, influenced by magnetization history, not electrical gating. This behavior can be electrically controlled. First-principles calculations show it results from charge transfer during CrOCl's phase transition, offering new insights for 2D device design.

Abstract

Anti-ferromagnetic insulator chromium oxychloride (CrOCl) has shown peculiar charge transfer and correlation-enhanced emerging properties when interfaced with other van der Waals conductive channels. However, the influence of its spin states to the channel material remains largely unknown. Here, this issue is addressed by directly measuring the density of states in bilayer graphene (BLG) interfaced with CrOCl via a high-precision capacitance measurement technique and a surprising hysteretic behavior in the charging states of the heterostructure is observed. Such hysteretic behavior depends only on the history of magnetization, but not on the history of electrical gating; it can also be turned off electrically, providing a synergetic control of these non-volatile states. First-principles calculations attribute this observation to magnetic field-controlled charge transfer between BLG and CrOCl during the phase transition of CrOCl from antiferromagnetic (AFM) to ferrimagnetic-like (FiM) states. This magnetic-electrical synergetic control mechanism broadens the scope of proximity effects and opens new possibilities for the design of advanced 2D heterostructures and devices.

The multi-color synaptic luminescence properties are successfully demonstrated in RE-doped Ca₂SnO₄ (RE = Sm³⁺, Er³⁺, and La³⁺), using long-persistent luminescence. Upon the introduction of serial UV pulses, the sample exhibits major synaptic potentiation features with multi-colors. By utilizing this multi-colored synaptic luminescence, human action recognition and interest point detection in video data processing are successfully demonstrated.

Abstract

Recently, there has been a surge of interest in neuromorphic computation inspired by the extraordinary characteristics of the human brain, such as low energy consumption, parallelism, adaptivity, cognitive abilities, and learning capabilities. Significant research efforts have focused on exploring optical synaptic behaviors in various functional materials. In this study, the potential of red, green and blue (RGB)-colored long-persistent luminescence (LPL) in Sm³⁺/Er³⁺/La³⁺-doped Ca₂SnO₄ is investigated for synaptic functionality. The luminescence of the samples is continuously enhanced under serial photoexcitation pulse applications, that is, the potentiation process, which is a key feature demonstrated in biological synapses. In addition, multichannel synaptic functionalities in the full-color range is successfully demonstrated by integrating individual RGB-colored Sm³⁺/Er³⁺/La³⁺-doped Ca₂SnO₄ into a single quantity. To validate the optical synaptic behavior of the samples in neuromorphic computing applications, a reservoir computing (RC) simulation is performed for space-time data processing using the unique responses of the samples under 4-bit excitation pulses. The results demonstrated that the multi-channel synaptic behaviors in the samples should be more valid for utilization in the RC layer than the single channel of synaptic behavior. We suggest this exploration holds promise for the advancement of synaptic devices employing LPL materials.

In this study, a series of traceless phosphorescent patterns are obtained using the UV laser photothermal effect and the water-absorbing quenching room temperature phosphorescence property of polyacrylamide. Two phosphorescent polymers with excellent UV laser stability are synthesized. This work implements the dual locking QR (quick response) code, misleading double QR code, labeling, and other prominent encryption applications.

Abstract

Organic room temperature phosphorescence (RTP) from polymers holds significant promise for information encryption and anti-counterfeiting applications. However, conventional patterning techniques limit the development of advanced RTP encryption, highlighting the need for an efficient method that achieves encryption processes quickly and conveniently. In this study, the UV laser marking machine is applied to create traceless phosphorescent patterns by leveraging the photothermal effect of the laser and the water-absorbent quenching RTP property of polyacrylamide. A series of biaryl derivative phosphors with low π-electron numbers are designed to limit UV absorption to below 355 nm, thereby preventing polymer sintering by the UV laser (355 nm). Additionally, two phosphorescent polymers, PB2COOH (phosphorescence lifetime τ _P = 2.34 s; phosphorescence quantum yield Φ _P = 13.59%) and PBN (τ _P = 1.46 s; Φ _P = 20.33%), possessing relatively excellent phosphorescent properties, are obtained. The controllable program and non-contact processing of the marking machine enable the rapid realization of complex patterns, such as the Twelve Chinese Zodiac Signs, effectively overcoming the constraints of traditional techniques. Based on this laser technology, applications such as dual-locking QR (quick response) codes, misleading double QR codes, labeling, and other advanced encryption methods are developed.

A series of chiral thermally activated delayed fluorescence polymers (R/S)-E-x (x = 0.02, 0.05, and 0.1) are designed and prepared. Impressively, solution-processable single-emitting-layer circularly polarized white organic light-emitting diode is achieved by employing the chiral polymers and 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) via electroplex emission strategy, which shows the best performances with a maximum external quantum efficiency of 15.1% and charming electroluminescence dissymmetry factor of 2.4 × 10⁻³.

Abstract

Achieving efficient circularly polarized white organic light-emitting diode (CP-WOLED) remains a significant challenge. In this study, a proof-of-concept for realizing CP-WOLED is proposed using an electroplex emission strategy between a chiral thermally activated delayed fluorescence (TADF) emitter and hole-transporting material. A series of chiral polymers (R/S)-E-x (x = 0.02, 0.05, and 0.1) are designed and prepared via random copolymerization of a chiral chromophore and styrene moiety, which shows typical TADF character. The neat film of (R/S)-E-0.1 presents distinct chiroptical properties with a dissymmetry factor (|g _lum|) of 2.8 × 10⁻³. Notably, solution-processable, single-emitting-layer CP-WOLEDs are fabricated using these chiral polymers in combination with 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) as the emitter, achieving a record maximum external quantum efficiency of 15.1% and Commission Internationale de lʹeclairage coordinate of (0.36, 0.40). Importantly, these CP-WOLEDs exhibit an impressive |g _EL| value of 2.4 × 10⁻³. This research provides a straightforward and effective strategy for the realization of high-performance CP-WOLED.

Inspired by the unique microstructures of locust toe pads, this study presents high-temperature-resistant friction pads made from silicone rubber with different radii of curvature of the microstructure. The high-temperature non-destructive handling experiment using a robotic arm verifies the feasibility of bionic high-temperature friction pads in industrial applications and provides a valuable solution.

Abstract

Non-destructive handling such as wafer handling usually requires a high-temperature environment, however, most bionic materials fail in high temperatures due to material decomposition. In this study, inspired by the unique microstructure of locust toe pads with low adhesion and high friction, bionic high-temperature friction pads are designed and fabricated, selecting high-temperature-resistant silicone rubber as the material. The interfacial mechanical properties at high temperatures are analyzed. The samples with terminal bulges possess preferable roughness adaptability, enabling the advantages of low adhesion and high friction in high temperatures. The high-temperature non-destructive handling experiment using a robotic arm verifies the feasibility of bionic high-temperature friction pads in industrial applications and provides a valuable solution for non-destructive handling in high-temperature environments.

A recyclable liquid metal-silicon dioxide ink is proposed, which enables in-situ printing on diverse materials with high resolution and exceptional conductivity, thereby supporting the fabrication of wearable sensors for soft electronics and human–machine interaction.

Abstract

Leveraging the fluidity and excellent conductivity of liquid metal (gallium-indium alloy), liquid metal (LM) can be utilized to manufacture flexible and stretchable electronic products for applications in soft robotics, wearable devices, and human–machine interaction. However, the high surface tension and low surface adhesion of LM hinder its patterning and high-resolution fabrication of soft electronics. Here a recyclable LM-silicon dioxide (LMS) ink is proposed. Under stirring, silicon dioxide (SiO₂) particles are encapsulated by the oxide layer of the LM, consuming the oxide layer. Meanwhile, gallium in the LM reacts with oxygen from the air to form a new oxide layer, enhancing the adhesion of the LM to the substrate while maintaining its conductivity. The in-situ printing of LMS ink is verified on various materials (e.g., paper, polymer, and glass) with a resolution of up to 165 µm and an exceptional conductivity of ≈6.53 × 10⁶ S m⁻¹. The printed patterns can be erased with an anhydrous ethanol solution, allowing the recovered LMS ink to be reused for multiple writing cycles. The general method for direct LM circuits printing can fabricate various wearable sensors for soft electronic devices and human–machine interaction.

A high-performance zero thermal expansion with a negligible coefficient of thermal expansion (α _v = 2.7 ppm K⁻¹) over a broad temperature range (10–220 K) is achieved in ErCo_2.8Fe_0.2 magnet. The unique thermal-expansion-behavior transformation (negative to zero to positive thermal expansion) in Fe-doped Er-Co-Fe magnets is attributed to the significant magnetization thermal fluctuations-induced unconventional sublattice-magnetovolume effect in the Er atoms.

Abstract

Zero thermal expansion (ZTE) alloys are critically needed in sophisticated modern industries, including telescope manufacturing, satellite technology, and semiconductor production, owing to their exceptional dimensional stability. In this study, high-performance ZTE with a negligible coefficient of thermal expansion α _v = 2.7 ppm K⁻¹ over a broad temperature range of 10–220 K is discovered in ErCo_2.8Fe_0.2 magnet. Owing to an unconventional sublattice-magnetovolume effect in the Er atoms, the negative thermal expansion in Fe-substituted ErCo_{3− x} Fe _x magnets can be easily tuned to high-performance ZTE. Moreover, the direct visualization of the magnetic transition in the predominant magnetization from the Er to the Co/Fe sublattices, as observed by the Lorentz transmission electron microscopy, further elucidates the manipulation mechanism behind the high-performance ZTE. This study reports a convenient and effective strategy to optimize the thermal expansion characteristics of Er-Co-Fe magnets, which can guide future research that broadens the application scope of magnetic materials by leveraging the significant correlation between the magnetic properties and crystal structure of such systems.

In this work, a polarization-sensitive synaptic transistor based on nanowires is proposed, which simplifies the traditional polarized light detection system by using its unique photoelectric characteristics, and realizes the accurate recognition and analysis of complex biometric data at the level of a single device. This strategy breaks through the bottleneck of using natural light to obtain biological information technology and provides a new idea and technical path for a new generation of intelligent biometrics.

Abstract

In the digital age, biometric recognition technology is highly valued and widely used in biometrics, security detection, and personalized medicine. This demands more efficient and diverse extraction methods. Traditional techniques rely on natural light, often failing to capture all necessary information and facing issues like high energy consumption and bulky design due to component separation, thus not meeting current high demands. In this paper, a polarization-sensitive synaptic phototransistor based on perovskite nanowire is developed using nanoimprint technology, effectively integrating artificial photonic synapses with polarized light detection to enhance system integration. Notably, this device achieves a high polarization ratio of 2.2 under different polarization angles. Additionally, it features memory-like optical synapse functionality, improving fingerprint recognition accuracy by 225% compared to natural light. This technology overcomes the limitations of traditional optical systems, meeting the needs of security, medical, and research fields to a certain extent.

The quantification of the forces necessary to rupture the cell wall of a bacterium is relevant to understanding, for example, the action mechanisms of mechanobactericidal nanomaterials. This perspective collects and compares recent work on bacterial nanoindentation beyond rupture using atomic force microscopy. The influence of environmental and experimental parameters on the measured rupture forces is discussed, as well as the non-trivial transformation of force values into pressures.

Abstract

The interaction between bacteria and nanomaterials, particularly from a physical or mechanical perspective, has emerged as a topic of significant interest in both science and medicine. Mechanobactericidal nanomaterials, which exert antimicrobial effects through purely physical mechanisms, hold promise as alternative strategies to combat bacterial resistance to traditional antibiotics. High-aspect-ratio nanoparticles and surface topographies are being engineered to enhance their mechanobactericidal properties. However, progress in this field is hindered by an incomplete understanding of how these materials induce mechanical cell death in bacteria. This review examines the role of atomic force microscopy (AFM) nanoindentation in quantifying forces required to rupture the bacterial cell wall. The reported values range from nN to a few tens of nN, depending on the type of bacterium and the experimental conditions used. The potential effect of AFM tip properties, loading speed, bacterial immobilization strategy, or environmental conditions on the measured rupture values are discussed. This perspective also highlights the complexities of modeling bacterial cell rupture and the importance of pressure as a parameter for standardizing results across experiments. Furthermore, the implications of these quantitative insights to understand the mechanisms of action of mechanobactericidal nanomaterials are discussed.

A simple bio-inspired method for fabricating superhydrophobic surfaces with anisotropic properties by mimicking the surface structures of leek leaves is presented. Hydrophobic nanostructures are introduced into microstructures replicated from leek by applying a modified candle-soot coating. The resulting multifunctional surfaces show anisotropic wetting properties, anti-icing properties, mechanical durability, and optical transparency.

Abstract

A bio-inspired approach to fabricate robust superhydrophobic (SHB) surfaces with anisotropic properties replicated from a leek leaf is presented. The polydimethylsiloxane (PDMS) replica surfaces exhibit anisotropic wetting, anti-icing, and light scattering properties due to microgrooves replicated from leek leaves. Superhydrophobicity is achieved by a novel modified candle soot (CS) coating that mimics leek's epicuticular wax. The resulting surfaces show a contact angle (CA) difference of ≈30° in the directions perpendicular and parallel to the grooves, which is similar to the anisotropic properties of the original leek leaf. The coated replica is durable, withstanding cyclic bending tests (up to 10 000 cycles) and mechanical sand abrasion (up to 60 g of sand). The coated replica shows low ice adhesion (10 kPa) after the first cycle; and then, increases to ≈70 kPa after ten icing–shearing cycles; while, anisotropy in ice adhesion becomes more evident with more cycles. In addition, the candle soot-coated positive replica (CS-coated PR) demonstrates a transmittance of ≈73% and a haze of ≈65% at the wavelength of 550 nm. The results show that the properties depend on the replicated surface features of the leek leaf, which means that the leek leaf appears to be a highly useful template for bioinspired surfaces.

The differentiated design on intra-ligand charge transfer is first reported to realize multicolor responsive metal–organic framework (MOF) heterostructures, which display the distinct responsive MOF regions under the same mild stimuli and generate multiple tunable color patterns, further functioning as robust photonic barcodes with high-security convert states. These results provide enlightenment on the development of a smart-responsive MOF heterosystem for advanced anti-counterfeiting applications.

Abstract

Metal–organic framework (MOF) heterostructures with hybrid architectures and abundant functional sites possess great potential applications in advanced information security, yet still suffer from the harsh stimuli mechanisms with restrained emission control. Herein, the differentiated design strategy on intra-ligand charge transfer is first reported to realize smart-responsive multicolor MOF heterostructures as robust anticounterfeiting labels. Designed similar MOF blocks with the differentiated intra-ligand charge transfer are integrated via time-dependent epitaxial growth to form multicolor MOF heterostructures. Different numbers of electron-donating groups in MOF blocks offer distinct space regulation on the torsion of charge transfer ligands, which trigger the diverse responsive emissions under the same mild stimuli, thus generating multiple tunable color patterns in heterostructures. These spatial-resolved MOF heterostructures with stable multicolor responsive modes permit the encoding of fingerprint information, which further functions as robust anti-counterfeiting labels with high-security convert states. These results offer a promising route for the function-oriented exploitation of smart-responsive MOF heterosystems for advanced information anticounterfeiting.

This study explores the design and application of advanced nanometer-scale SERS-encoded probes with significant potential in multiplexed detection and high-resolution imaging down to the subcellular scale. With a high encoding capacity, cell sorting and imaging with 15 channels is demonstrated using a 1D encoding strategy, emphasizing its potential to enhance the capabilities of biosensing and imaging technologies.

Abstract

Optically-encoded probes have great potential for applications in the fields of biosensing and imaging. By employing specific encoding methods, these probes enable the detection of multiple target molecules and high-resolution imaging within the same sample. Among the various encoding methods, surface-enhanced Raman scattering (SERS) spectral encoding stands out due to its extremely narrow linewidth. Compared to fluorescence spectral encoding, SERS encoding significantly reduces crosstalk between adjacent peaks, thereby achieving a larger encoding capacity and enabling multi-channel parallel analysis. This article presents the design and construction of two novel sets of SERS-encoded probes based on noble metal core–shell nanostructures. Two different encoding strategies are successfully applied to encode the SERS spectra of the probes: 1D encoding based on the wavenumber of characteristic peaks in the SERS spectrum, and 2D encoding combining both wavenumber and intensity of characteristic peaks in the SERS spectrum. In addition, this study also demonstrates the potential application of 1D encoded probes in cell sorting. These studies verify the feasibility of applying these two encoding methods to SERS core–shell probes and provide new insights into the construction of optically encoded probes.

Nature Communications, Published online: 10 November 2024; doi:10.1038/s41467-024-53988-7

Hyperbolic polaritons in van der Waals materials are light-matter excitations holding potential for nanophotonics applications, but they are mostly observed in the mid-infrared range. Here, the authors report the observation of low-loss in-plane hyperbolic plasmon polaritons in MoOCl2 thin-films at visible and near-infrared frequencies.