Jing Zhang

Magnetic modular microrobots that can change their end-effectors to achieve different functions are presented. The two modules, the magnetic base and the end-effector, are connected by a responsive mating component made from hydrogel materials, fabricated with two-photon polymerization. The modular microrobots successfully demonstrate with their ability to exchange end-effectors and perform micromanipulation applications.

Abstract

Microrobots show great potential in biomedical applications such as drug delivery and cell manipulations. However, current microrobots are mostly fabricated as a single entity and type and the tasks they can perform are limited. In this paper, modular microrobots, with an overall size of 120 µm × 200 µm, are proposed with responsive mating components, made from stimuli-responsive hydrogels, and application specific end-effectors for microassembly tasks. The modular microrobots are fabricated based on photolithography and two-photon polymerization together or separately. Two types of modular microrobots are created based on the location of the responsive mating component. The first type of modular microrobot has a mating component that can shrink upon stimulation, while the second type has a double bilayer structure that can realize an open and close motion. The exchange of end-effectors with an identical actuation base is demonstrated for both types of microrobots. Finally, different manipulation tasks are performed with different types of end-effectors.

This study reports thickness-dependent dewetting modes in printed polymer droplets with coffee-ring-like morphology. These dewetting modes are activated by thermal annealing and relies on multiple molecular transport processes that are driven by interfacial interactions within microscopically confined polymeric features. The selective assembly of quantum dots over polymeric features leads to deterministic and stochastic features for anti-counterfeiting applications.

Abstract

Molecular transport processes in printed polymer droplets hold enormous importance for understanding wetting phenomena and designing systems in applications such as encoding, electronics, photonics, and sensing. This paper studies thickness-dependent dewetting modes that are activated by thermal annealing and driven by interfacial interactions within microscopically confined polymeric features. The printing of poly(2-vinylpyridine) is performed in a regime where coffee-ring effects lead to strong thinning of the central region of the deposit. Thermal annealing leads to two different modes of dewetting that depend on the thickness of the central region. Mode I refers to the formation of randomly positioned small features surrounded by large hemispherical ones located along the periphery of the printed features and occurs when the central regions are thin. Observed at large central thicknesses, Mode II mediates significant molecular transport from edges toward the center of the printed droplet with thermal annealing and forms a hemispherical feature from the initial ring-like deposit. The selective adsorption of red, green, and blue emitting quantum dots over the poly(2-vinylpyridine) results in photoluminescent patterns. The selective assembly of photoluminescent quantum dots over patterned surfaces leads to deterministic and stochastic features beneficial to creating security labels for anti-counterfeiting applications.

An All-in-One piezoelectric multidirectional bending sensor is proposed. The design strategy based on dual piezoelectric modes enables the sensor to obtain significantly improved anisotropy. The All-in-One architecture based on interconnected and micro-interlocked interfaces enables the sensor to achieve breakthrough mechanical stability, with up to 1.6 million bending cycles.

Abstract

Flexible bending sensors are crucial components of flexible/wearable electronics. However, their broad application is restricted by their difficulty in sensing different bending directions and, more importantly, their significant output attenuation after long cycles. Herein, a new design of an All-in-One piezoelectric bending sensor is proposed, in which double-deck, cross-over 3D interdigital microelectrodes (silver nanowires (Ag NWs)) are embedded in a piezoelectric polymer film (poly(vinylidene fluoride-trifluoroethylene (P(VDF-TrFE))). The piezoelectric film with the embedded 3D microelectrodes exhibits a high anisotropy coefficient (η90∘${{\eta }_{90^\circ }}$ > 1) based on dual piezoelectric modes (d₃₁ and d₃₃ ), which renders it more sensitive to different bending directions. More importantly, the homogeneous interconnected interface and heterogeneous microinterlocked interface formed inside the sensor significantly enhance its interface mechanical properties, with at least a tensile strength of 51 MPa, a shear strength of 28 MPa, and an interfacial toughness of 300 J m⁻², which are nearly two orders of magnitude greater than those of conventional sandwich architectures. The prepared All-in-One sensor shows an extremely stable piezoelectric output over as many as 16 00 000 bending cycles, which represents a remarkable breakthrough. Furthermore, a single sensor can be used to remotely control the multidirectional motion of a smart car, demonstrating enormous potential in practical applications.

In the history of MAX phase, in-plane and out-of-plane ordered configurations are reported for n = 1 and n ≥ 2 in M_n+1AlC_n separately. Here, starting from the (Mo, Nb)₄AlC₃ o-MAX, the novel Mo_{3.33- x}R _0.67Nb _x AlC₃ (R = Y, Gd-Tm, Lu) super-ordered (s-)MAX phase is synthesized with simultaneous R in-plane-ordering and Mo/Nb out-of-plane-ordering. The Pt-anchored 2D s-MXene shows supreme HER performance.

Abstract

Nanolamellar transition metal carbides are gaining increasing attentions because of the promising application in energy storage of their 2D derivatives. There are in-plane and out-of-plane atomic ordered occupations, which is thought to only be formed in separated systems due to totally different origins and crystallographic structure. In present work, starting from (Mo, Nb)₄AlC₃ o-MAX phase where out-of-plane ordered occupation is experimentally and theoretically proved for Mo/Nb atoms, rare-earth elements (R = Y, Gd-Tm, Lu) are introduced, and the novel Mo_{3.33- x}R _0.67Nb _x AlC₃ (x = 1, 1.25, 1.5, 1.75, 2, 2.25, and 2.5) super-ordered (s-) MAX phase is synthesized, where R is ordered at the outer layer in the strict stoichiometry meanwhile Mo/Nb maintains the out-of-plane ordered occupation. By R introduction, s-MAX is easier to be delaminated to obtain the s-MXene with the topochemical ordered vacancies, leading into the enhanced supercapacitance of 114.9 F g⁻¹ in Mo_1.33Nb₂C₃ s-MXene compared with 95.1 F g⁻¹ in Mo₂Nb₂C₃ o-MXene. By Pt anchoring, very low overpotential of 22 mV at a current density of 10 mA cm⁻² is achieved for HER applications. This study demonstrates a novel variety of s-MAX phase and seeks to inspire further exploration of the ordered MAX and MXene families.

Using X-ray imaging to track the kidney transport of renal-clearable gold nanoparticles, the study finds that inner strip of outer medulla is the most significant site in accumulating glomerular filtered nanoparticles in cisplatin-injured kidney: formation of gold–protein casts in the lumen of the loop of Henle increases as proximal tubular injury progresses, which is undetectable by renal function biomarkers BUN and creatinine in mild injury stages.

Abstract

Renal function biomarkers such as serum blood urea nitrogen (BUN) and creatinine (Cr) serve as key indicators for guiding clinical decisions before administering kidney-excreted small-molecule agents. With engineered nanoparticles increasingly designed to be renally clearable to expedite their clinical translation, understanding the relationship between renal function biomarkers and nanoparticle transport in diseased kidneys becomes crucial to their biosafety in future clinical applications. In this study, renal-clearable gold nanoparticles (AuNPs) are used as X-ray contrast agents to noninvasively track their transport and retention in cisplatin-injured kidneys with varying BUN and Cr levels. The findings reveal that AuNP transport is significantly slowed in the medulla of severely injured kidneys, with BUN and Cr levels elevated to 10 times normal. In mildly injured kidneys, where BUN and Cr levels only four to five times higher than normal, AuNP transport and retention are not predictable by BUN and Cr levels but correlate strongly with the degree of tubular injury due to the formation of gold–protein casts in the Henle's loop of the medulla. These results underscore the need for caution when employing renal-clearable nanomedicines in compromised kidneys and highlight the potential of renal-clearable AuNPs as X-ray probes for assessing kidney injuries noninvasively.

Plant epidermal cell walls bear increasing loads even after plastic deformation. The multiscale structural characterization of walls under strain reveals realignment of cellulose networks, close packing of cellulose microfibrils and the stretching of cellulose backbones, suggesting that the molecular crowding of cellulose upon sliding may enable further stretching of celluloses for the wall to bear higher loads.

Abstract

The molecular foundations of epidermal cell wall mechanics are critical for understanding structure–function relationships of primary cell walls in plants and facilitating the design of bioinspired materials. To uncover the molecular mechanisms regulating the high extensibility and strength of the cell wall, the onion epidermal wall is stretched uniaxially to various strains and cell wall structures from mesoscale to atomic scale are characterized. Upon longitudinal stretching to high strain, epidermal walls contract in the transverse direction, resulting in a reduced area. Atomic force microscopy shows that cellulose microfibrils exhibit orientation-dependent rearrangements at high strains: longitudinal microfibrils are straightened out and become highly ordered, while transverse microfibrils curve and kink. Small-angle X-ray scattering detects a 7.4 nm spacing aligned along the stretch direction at high strain, which is attributed to distances between individual cellulose microfibrils. Furthermore, wide-angle X-ray scattering reveals a widening of (004) lattice spacing and contraction of (200) lattice spacing in longitudinally aligned cellulose microfibrils at high strain, which implies longitudinal stretching of the cellulose crystal. These findings provide molecular insights into the ability of the wall to bear additional load after yielding: the aggregation of longitudinal microfibrils impedes sliding and enables further stretching of the cellulose to bear increased loads.

The genomic landscape of a cell surface protein reveals how neuron identity is displayed

Nature, Published online: 24 July 2024; doi:10.1038/s41586-024-07606-7

A regional atlas of the ageing human brain—spanning six distinct anatomical regions from individuals with and without Alzheimer’s dementia—provides insights into cellular vulnerability, response and resilience to Alzheimer’s disease pathology

The precise and programmable assembly of multiple cells into complex 3D cell sheet architectures is of utmost importance but currently remains challenging. A biodegradable nanochannel membrane is thus created and combined with vacuum-guided cell assembly for generating versatile 3D cell sheet architectures; the formed tissues are further demonstrated for modeling and repairing slow-healing murine diabetic skin wounds as a proof-of-concept.

Abstract

The ability to precisely arrange and control the assembly of diverse cell types into intricate 3D structures remains a critical challenge in tissue engineering. Herein, a versatile and programmable 3D cell sheet assembly is described technology by developing a biodegradable nanochannel (BNC) membrane to fulfill this unmet need. This membrane, hierarchically assembled from 2D nanomaterial aggregates, exhibits both exceptional fluid permeability and rapid biodegradation under physiological conditions. The unique properties of the BNC membrane enable precise spatial and temporal control over cell assembly, facilitating the creation of complex 3D cellular architectures. The BNC membrane is integrated with a programmable negative-pressure-based cell assembly strategy to form single and multicellular 3D sheets in a highly controllable manner. To demonstrate the feasibility and translatability of this technology in the field of tissue engineering approaches to screen stem cell-derived therapeutics with “core–shell” macrophage-fibroblast multicellular patterns and treat murine diabetic skin wounds via scaffold-free 3D adipose-derived mesenchymal stem cell (ADMSC) sheets are devised. In summary, the results demonstrate that the BNC membrane-based 3D cell sheet assembly approach significantly advances current tissue engineering capabilities, offering substantial potential for both regenerative medicine applications and the development of physiologically relevant disease models.

A versatile molecular soldering-governed defect engineering strategy is proposed to simultaneously control the microscale, mesoscale, and macroscale structural defects in wet-spun MoS₂ semiconducting fibers, which affords two orders of magnitude enhancement in responsivity and remarkable mechanical robustness, thus enabling large-scale weaving of reliable smart textile optoelectronic systems.

Abstract

Semiconducting fibers (SCFs) are of significant interest to design next-generation wearable and comfortable optoelectronics that seamlessly integrate with textiles. However, the practical applications of current SCFs are always limited by poor optoelectronic performance and low mechanical robustness caused by uncontrollable multiscale structural defects. Herein, a versatile in situ molecular soldering-governed defect engineering strategy is proposed to construct ultrahigh responsivity and robust wet-spun MoS₂ SCFs, by using a π-conjugated dithiolated molecule to simultaneously patch microscale sulfur vacancies within MoS₂ nanosheets, diminish mesoscale interlayer voids/wrinkles, promote macroscale orientation, build long-range photoelectron percolation bridges, and provide n-doping effect. The derived MoS₂ SCFs exhibit over two orders of magnitude higher responsivity (144.3 A W⁻¹) than previously reported fiber photodetectors, 37.3-fold faster photoresponse speed (52 ms) than pristine counterpart, and remarkable bending robustness (retain 94.2% of the initial photocurrent after 50 000 bending-flattening cycles). Such superior robustness and photodetection capacity of MoS₂ SCFs further enable large-scale weaving of reliable smart textile optoelectronic systems, such as direction-identifiable wireless light alarming system, modularized mechano-optical communication system, and indoor light-controlled IoT system. This work offers a universal strategy for the scalable production of mechanically robust and high-performance SCFs, opening up exciting possibilities for large-scale integration of wearable optoelectronics.

Nature Electronics, Published online: 22 July 2024; doi:10.1038/s41928-024-01221-0

Oxide dielectrics that grow on 2D materials

Magnetically sensitive micropatterns are obtained by inkjet printing on uncured polydimethylsiloxane. The ink consisted of synthesized magnetic colloidal nanocrystal clusters with proper surface modification. Nanocrystal clusters formed photonic crystals under applied magnetic field and provided a tunability of structural color.

Abstract

Magnetic colloidal nanocrystalline clusters (MCNCs) exhibit a color-changing response to a magnetic field due to their tunable assembly into photonic crystals demonstrating visible light diffraction. The use of this response to obtain a magnetically sensitive color micropattern on the surface of a solid substrate requires appropriate scalable technologies for deposition of MCNCs. Here, inkjet printing of MCNCs onto the surface of a solid substrate coated with uncured polydimethylsiloxane is addressed and demonstrate their capability to form desired patterns with structural colors from blue to red controlled by external magnetic field. The results, thereby, pave the way to semi-commercial manufacture an anticounterfeiting imaging at a large scale.

Through the construction of a double-dielectric layer/Si substrate, the creation of phase singularity by introducing zero-reflection in monolayer MoS₂ facilitates the fast and quantitative detection of infectious 2019-nCov antigen. The topological phase singularity together with topological charge based on materials of atomic layers broadens the scope of flexible wavefront shaping beyond metastructures.

Abstract

Manipulation of wavefront lies at the core of next-generation information technologies. Compared to metal and dielectric metasurfaces, atomic 2D materials exhibit excellent prospects toward fulfilling ultra-thin thickness requirements in flat optics in wavefront shaping, with thickness much smaller than those of traditional bulky devices. However, phase manipulation by light propagating through atomic 2D materials is suppressed due to its sub-nanometer thickness. Here, an approach is reported to realize reflection phase singularities by establishing a zero-reflection point in a monolayer MoS₂-based multilayer system, which broadens topological study beyond polarization singularity. This is achieved through the creation of a multilayer Fabry-Perot-type interference, and a pronounced phase change in the reflected light is realized due to the high absorption of monolayer MoS₂ in the studied wavelength range. As an application, a rapid, sensitive, and label-free detection of SARS-CoV-2 (2019-nCov) antigen is demonstrated with a detection limit of 10⁻¹² M L⁻¹ (62 pg ml⁻¹) by using monolayer MoS₂ based optical biosensor. In addition to offering a comprehensive study in phase singularity, efficient wavefront engineering based on the reflective system using materials is presented with atomic thickness which may greatly simplify optical architecture in flat optics, and promote its development toward compactness and integrated functions.

A facile yet efficient off-stoichiometry protocol enables the precise synthesis of 0D organic–inorganic metal halide polycrystals within seconds, and the key lies in the meticulous control of metal polyhalide intermediates in the solution. The resulting scintillator films exhibit a superior light yield compared to commercial LuAG:Ce, accompanied by a commendable spatial resolution of 8.3 lp mm⁻¹.

Abstract

0D organic–inorganic metal halides (OIMHs) with intriguing luminescence encoded in their diverse crystal structure open wide opportunities for next-generation optoelectronics. Yet, this structural diversity makes their precise synthesis challenging. Here, a facile yet efficient off-stoichiometry antisolvent precipitation protocol is devised to synthesize pure Bmpip₂PbBr₄ (Bmpip = 1-butyl-1-methylpiperidinium) polycrystals. Optical investigations reveal that the key to suppressing the by-product, Bmpip₉[Pb₃Br₁₁][PbBr₄]₂, generally occurring in a typical stoichiometric synthesis is to create a Br-rich environment to promote the [PbBr₄]²⁻ formation while suppressing the formation of [Pb₃Br₁₁]⁵⁻. Moreover, this off-sociometric protocol can be extended to the precise synthesis of Bzmim₃SbCl₆ (Bzmim = 1-benzyl-3-methylimidazolium) polycrystals through the meticulous control of [SbCl₆]³⁻ formation in the solution. The resulting Bzmim₃SbCl₆ polycrystals show a nominal light yield of 24600 photons MeV⁻¹, which is 6.8 times higher than that of its by-product, namely Bzmim₂SbCl₅, and outperforms that of commercial LuAG:Ce. As a result, the scintillators made of Bzmim₃SbCl₆@PMMA achieve a decent spatial resolution of 8.3 lp mm⁻¹. This work highlights the importance of regulating the metal polyhalide intermediates in precisely synthesizing 0D OIMHs.

Thick-Layer OLEDs

In article number 2401434, Zujin Zhao and co-workers report two tailored blue luminescent molecules consisting of ring-fused carbonyl-containing acceptors and spiro-acridine donors. They hold ultrafast bipolar charge transport and strong solid-state delayed fluorescence in neat films, and the state-of-the-art electroluminescence performances are achieved not only in thin-layer organic light-emitting diodes but also simplified thick-layer ones with obviously improved operational lifetimes.

Visible/UV-light-driven photosensitive photoluminescent metallopolymers with good mechanical properties and fast self-healing behaviors are successfully developed by incorporating spiropyran and terpyridine components into a unified lanthanide polymer structure. By adjusting the proportions of raw material, precise control over the stimulus response and luminescent color can be achieved. The obtained polymers have been applied for dynamic information encryption, UV-sensing, and Light-writing fields.

Abstract

Photoluminescent metallopolymers displaying photo-stimuli-responsive properties are emerging as promising materials with versatile applications in photo-rewritable patterns, wearable UV sensors, and optical encryption anti-counterfeiting. However, integrating these materials into practical applications that require fast response times, lightweight qualities, fatigue resistance, and multiple encryption capabilities poses challenges. In this study, luminescent photochromic lanthanide (Ln) metallopolymers with rapid self-healing properties are developed by cross-linking terpyridine (Tpy)- and spiropyran (SP)- functionalized polyurethane chains through Ln-Tpy coordination bonds and H-bonds among polymer chains. The resulting products exhibit a range of intriguing features: i) photo-stimuli responsiveness using spiropyran monomers without additional dopants; ii) dual-emitting performance under UV-light due to Ln-Tpy and open-ring spiropyran moieties; iii) satisfactory mechanical properties and self-healing abilities from polymer chains; iv) multiple control switches for luminescence colors through photostimulation or feed ratio adjustments. Leveraging these attributes, the developed material introduces novel opportunities for light-writing applications, advanced information encryption, UV-sensing wearable devices, and insights into designing multifunctional intelligent materials for the future.

Liquid microcarriers are attractive solutions to enable cell culture in a scalable format, for stem cell manufacturing and applications in regenerative medicine. Here, iPSCs are cultured at the surface of microdroplets for the first time. This process is enabled by the self-assembly of strong elastic protein nanosheets that stabilize microdroplets, reinforce interfacial mechanics and engage cell adhesion receptors.

Abstract

Advances in stem cell technologies, revolutionizing regenerative therapies and advanced in vitro testing, require novel cell manufacturing pipelines able to cope with scale up and parallelization. Microdroplet technologies, which have transformed single cell sequencing and other cell-based assays, are attractive in this context, but the inherent soft mechanics of liquid-liquid interfaces is typically thought to be incompatible with the expansion of induced pluripotent stem cells (iPSCs), and their differentiation. In this work, the design of protein nanosheets stabilizing liquid-liquid interfaces and enabling the adhesion, expansion and retention of stemness by iPSCs is reported. Microdroplet microfluidic chips are used to control the formulation of droplets with defined dimensions and size distributions. The resulting emulsions sustain high expansion rates, with excellent retention of stem cell marker expression. iPSCs cultured in such conditions retain the capacity to differentiate into cardiomyocytes. This work provides clear evidence that local nanoscale mechanics, associated with interfacial viscoelasticity, provides strong cues able to regulate and maintain pluripotency, as well as to support commitment in defined differentiation conditions. Microdroplet technologies appear as attractive candidates to transform cell manufacturing pipelines, bypassing significant hurdles paused by solid substrates and microcarriers.

A micro-well structured plasmonic film with in situ grown dendritic Ag nanostructures is developed for plant wearable surface-enhanced Raman spectroscopy (SERS) detection. The film capitalizes on the concentration enrichment of analytes through droplet evaporation within the microwell, facilitating ultrasensitive detection. Additionally, this film offers dual-sided detection and allows for multiplexed identification of target analytes, expanding its utility in precision agriculture, bio-sensing, and environmental surveillance.

Abstract

Plant wearable detection has garnered significant interest in advancing agricultural intelligence and promoting sustainable food production amidst the challenges of climate change. Accurately monitoring plant health and agrochemical residue levels necessitates qualities such as precision, affordability, simplicity, and noninvasiveness. Here, a novel attachable plasmonic film is introduced and designed for on-site detection of agrochemical residues utilizing surface-enhanced Raman spectroscopy (SERS). By functionalizing a thin polydimethylsiloxane film with silver nanoparticles via controlled droplet reactions in micro-well arrays, a plasmonic film is achieved that not only maintains optical transparency for precise analyte localization but also conforms closely to the plant surface, facilitating highly sensitive SERS measurements. The reliability of this film enables accurate identification and quantification of individual compounds and their mixtures, boasting an ultra-low detection limit ranging from 10⁻¹⁶ to 10⁻¹³ m, with mini mal relative standard deviation. To showcase its potential, on-field detection of pesticide residues on fruit surfaces is conducted using a handheld Raman spectrometer. This advancement in fabricating plasmonic nanostructures on flexible films holds promise for expanding SERS applications beyond plant monitoring, including personalized health monitoring, point-of-care diagnosis, wearable devices for human–machine interface, and on-site monitoring of environmental pollutants.

The ionic photovoltaics-in-memory has been found in centrosymmetric CdSb₂Se₃Br₂. The migration of Br ions induces a reversible modulation of the built-in electric field, resulting in significant anisotropy and electrically-induced nonvolatile photovoltaic currents. Consequently, a highly secure circuit with electrical and optical keys is implemented. It opens up new possibilities for cutting-edge optoelectronic devices.

Abstract

The photovoltaic effect is gaining growing attention in the optoelectronics field due to its low power consumption, sustainable nature, and high efficiency. However, the photovoltaic effects hitherto reported are hindered by the stringent band-alignment requirement or inversion symmetry-breaking, and are challenging for achieving multifunctional photovoltaic properties (such as reconfiguration, nonvolatility, and so on). Here, a novel ionic photovoltaic effect in centrosymmetric CdSb₂Se₃Br₂ that can overcome these limitations is demonstrated. The photovoltaic effect displays significant anisotropy, with the photocurrent being most apparent along the CdBr₂ chains while absent perpendicular to them. Additionally, the device shows electrically-induced nonvolatile photocurrent switching characteristics. The photovoltaic effect is attributed to the modulation of the built-in electric field through the migration of Br ions. Using these unique photovoltaic properties, a highly secure circuit with electrical and optical keys is successfully implemented. The findings not only broaden the understanding of the photovoltaic mechanism, but also provide a new material platform for the development of in-memory sensing and computing devices.

Advanced Materials, Volume 36, Issue 38, September 19, 2024.

Nature Nanotechnology, Published online: 22 July 2024; doi:10.1038/s41565-024-01732-z

In Bi2O2Se thin films, the local inversion-symmetry breaking in two sectors of the [Bi2O2]2+ layer yields opposite Rashba spin polarizations, which compensate each other and give rise to the hidden Rashba effect. Hence, the films exhibit only even-integer quantum Hall states, but there is no sign of odd-integer states.

Nature Nanotechnology, Published online: 23 July 2024; doi:10.1038/s41565-024-01705-2

Monolithic 3D integration of complementary WSe2 FETs has been achieved, featuring n-type FETs in tier 1 and p-type FETs in tier 2. Dense vias are realized using a pitch of less than 1 µm, facilitating 3D inverters as well as NAND and NOR logic functionalities.