Turning Polysaccharides into Injectable and Rapid Self-Healing Antibacterial Hydrogels for Antibacterial Treatment and Bacterial-Infected Wound Healing.

Great efforts have been devoted to the development of novel and multifunctional wound dressing materials to meet the different needs of wound healing. Herein, we covalently grafted quaternary ammonium groups (QAGs) containing 12-carbon straight-chain alkanes to the dextran polymer skeleton. We then oxidized the resulting product into oxidized quaternized dextran (OQD). The obtained OQD polymer is rich in antibacterial QAGs and aldehyde groups. It can react with glycol chitosan (GC) via the Schiff-base reaction to form a multifunctional GC@OQD hydrogel with good self-healing behavior, hemostasis, injectability, inherent superior antibacterial activity, biocompatibility, and excellent promotion of healing of methicillin-resistant Staphylococcus aureus (MRSA)-infected wounds. The biosafe and nontoxic GC@OQD hydrogel with a three-dimensional porous network structure possesses an excellent swelling rate and water retention capacity. It can be used for hemostasis and treating irregular wounds. The designed GC@OQD hydrogel with inherent antibacterial activity possesses good antibacterial efficacy on both S. aureus (Gram-positive bacteria) and Escherichia coli (Gram-negative bacteria), as well as MRSA bacteria, with antibacterial activity greater than 99%. It can be used for the treatment of wounds infected by MRSA and significantly promotes the healing of wounds. Thus, the multifunctional antibacterial GC@OQD hydrogel has the potential to be applied in clinical practice as a wound dressing.

A redox homeostasis disruptor based on a biodegradable nanoplatform for ultrasound (US) imaging-guided high-performance ferroptosis therapy of tumors.

The synergistic disruption of intracellular redox homeostasis through the combination of ferroptosis/gas therapy shows promise in enhancing the antitumor efficacy. However, the development of an optimal delivery system encounters significant challenges, including effective storage, precise delivery, and controlled release of therapeutic gas. In this study, we propose the utilization of a redox homeostasis disruptor that is selectively activated by the tumor microenvironment (TME), in conjunction with our newly developed nanoplatforms (MC@HMOS@Au@RGD), for highly efficient ferroptosis therapy of tumors. The TME-triggered degradation of HMOS initiates the release of MC and AuNPs from the MC@HMOS@Au@RGD nanoplatform. The released MC subsequently reacts with endogenous hydrogen peroxide (H2O2) and H+ to enable the on-demand release of CO gas, leading to mitochondrial damage. Simultaneously, the released AuNPs exhibit GOx-like activity, catalyzing glucose to generate gluconic acid and H2O2. This process not only promotes the decomposition of MnCO to enhance CO production but also enhances the Fenton-like reaction between Mn2+ and H2O2, generating ROS through the modulation of the H+ and H2O2-enriched TME. Moreover, the generation of CO bubbles enables the monitoring of the ferroptosis treatment process through ultrasound (US) imaging. The efficacy of our prepared MC@HMOS@Au@RGD disruptors in ferroptosis therapy is validated through both in vitro and in vivo experiments.

A strategy of disrupted redox homeostasis specifically initiated by the tumor microenvironment and our constructed MC@HMOS@Au@RGD nanoplatforms is proposed for ultrasound (US) imaging-guided potent ferroptosis therapy of tumors.

A Simple-Structured Perovskite Wavelength Sensor for Full-Color Imaging Application.

In this study, simple-structured wavelength sensors were developed by depositing two back-to-back Au/MAPbI3/Au photodetectors on an MAPbI3 single crystal. This sensor could quantitatively distinguish wavelengths. Further device analysis showed that both photodetectors possess entirely disparate optoelectronic properties. Consequently, the as-developed wavelength sensor could accurately distinguish incident-light wavelengths ranging from 265 to 860 nm with a resolution of less than 1.5 nm based on the relation between the photocurrent ratios of both photodetectors and the incident light wavelengths. Notably, a high resolution and wide detection range are among the optimum reported values for such sensors and enable full-color imaging. Furthermore, technology computer-aided design (TCAD) simulations showed that a mechanism involved in distinguishing wavelengths is attributed to the wavelength-dependent photon generation rate in MAPbI3 single crystals. The high-performance MAPbI3 wavelength sensor can potentially drive the research progress of perovskites in wavelength recognition and full-color imaging.

Two-dimensional CdS/SnS2 heterostructure: a highly efficient direct Z-scheme water splitting photocatalyst.

A desired water splitting photocatalyst should not only possess a suitable bandgap and band edge position, but also host the spontaneous progress for overall water splitting without the aid of any sacrificial agents. In this work, we propose a two-dimensional CdS/SnS2 heterostructure (CSHS) as a possible water splitting photocatalyst by first-principles calculations. The CSHS enhances the absorption of visible and infrared light, and the type-II band alignment guarantees the spatial separation of the photoinduced carriers. The induced built-in electric field across the CSHS interface efficiently separates the photoexcited carriers and extends their carrier lifetimes. All these properties make the CSHS a direct Z-scheme system with the hydrogen and oxygen evolution reactions occurring, respectively, at the CdS and SnS2 layers. More encouragingly, the introduction of a S-vacancy into SnS2 could effectively lower the overpotential of the oxygen evolution reaction, thus ensuring the overall water redox reaction to be achieved spontaneously under light irradiation. Our findings suggest that the CSHS is a promising water splitting photocatalyst.

Highly Sensitive Ultraviolet and Visible Wavelength Sensor Composed of Two Identical Perovskite Nanofilm Photodetectors.

This work reports the design of a wavelength sensor composed of two identical perovskite (FA0.85 Cs0.15 PbI3 ) photodetectors (PDs) that are capable of discriminating incident wavelength in a quantitative way. Due to strong wavelength-dependent absorption coefficient, the penetration depth of the photons in the FA0.85 Cs0.15 PbI3 nanofilms increases with the increasing wavelength, leading to a gradual decrease of photo-generated current for PD1, but an increase of photocurrent in PD2, according to the theoretical simulation of Technology Computer Aided Design. This special evolution of photo-generated current as a function of wavelength facilitates the quantitative determination of the wavelength since the current ratio of both PDs monotonously decreases with the increase of wavelength from 265 to 810 nm. The average absolute error and the average relative error are estimated to be 7.6 nm and 1.68%, respectively, which are much better than other semiconductors materials-based wavelength sensors previously reported. It is believed that the present perovskite film-based wavelength sensor will have potential application in the future color/spectrum optoelectronic devices.

Highly efficient BiVO4single-crystal nanosheets with dual modification: phosphorus doping and selective Ag modification.

BiVO4, a visible-light response photocatalyst, has shown tremendous potential because of abundant raw material sources, good stability and low cost. There exist some limitations for further applicaitions due to poor capability to separate electron-hole pairs. In fact, a single-component modification strategy is barely adequate to obtain highly efficient photocatalytic performance. In this work, P substituted some of the V atoms from VO4oxoanions, namely P was doped into the V sites in the host lattice of BiVO4by a hydrothermal route. Meanwhile, Ag as an attractive and efficient electron-cocatalyst was selectively modified on the (010) facet of BiVO4nanosheets via facile photo-deposition. As a result, the obtained dually modified BiVO4sheets exhibited enhanced photocatalytic degradation property of methylene blue (MB). In detail, photocatalytic rate constant (k) was 2.285 min-1g-1, which was 2.78 times higher than pristine BiVO4nanosheets. Actually, P-doping favored the formation of O vacancies, led to more charge carriers, and facilitated photocatalytic reaction. On the other hand, metallic Ag loaded on (010) facet effectively transferred photogenerated electrons, which consequently helped electron-hole pairs separation. The present work may enlighten new thoughts for smart design and controllable synthesis of highly efficient photocatalytic materials.

Increased fes1a thermotolerance is induced by BAG6 knockout.

KEY MESSAGE: (1) The fes1a bag6 double mutant shows an increased short term thermotolerance compared to fes1a. BAG6 is a suppressor of Fes1A; (2) IQ motif is essential to effective performance of BAG6. (3) Calmodulin was involved in signal transduction. (4) BAG6 is localized in the nucleus. HSP70s play an important role in the heat-induced stress tolerance of plants. However, effective HSP70 function requires the assistance of many co-chaperones. BAG6 and Fes1A are HSP70-binding proteins that are critical for Arabidopsis thaliana thermotolerance. Despite this importance, little is known about how these co-chaperones interact. In this study, we assessed the thermotolerance of a fes1a bag6 double mutant. We found that the fes1a bag6 double mutant shows an increased short-term thermotolerance compared to fes1a. However, calmodulin inhibitors diminished this enhanced thermotolerance in the fes1a bag6 double mutant. In addition, we found the IQ motif to be essential for effective BAG6 performance. Since BAG6 is localized in the nucleus, the signal transduction is likely to involve nuclear calcium signaling.

Double mutation of BRF1 and BRF2 leads to sterility in Arabidopsis thaliana.

The TFIIB-related factor (BRF) family plays vital roles in RNA polymerase (Pol) III transcription initiation. However, little is known about the role of BRF in plants. Here, we report BRF1 and BRF2 are involved in Arabidopsis reproduction. In this study, we generated BRF1 and BRF2 double mutant plants. We found that no homozygous double mutants of brf1brf2 were obtained when brf1 and brf2 were crossed, although brf1 and brf2 mutants individually developed and reproduced normally. Further experiments revealed that heterozygous brf1/ + brf2/ + produced abnormal pollen and had no seeds in some placentas of siliques. Genetic data derived from reciprocal crosses showed that BRF2 plays a dominant role in Arabidopsis reproduction. Taken together, a double mutation of BRF1 and BRF2 results in a high degree of aborted macrogametes and microgametes and complete failure in zygote generation, ultimately leading to sterility.

Electrical property of macroscopic graphene composite fibers prepared by chemical vapor deposition.

Graphene fibers are promising candidates in portable and wearable electronics due to their tiny volume, flexibility and wearability. Here, we successfully synthesized macroscopic graphene composite fibers via a two-step process, i.e. first electrospinning and then chemical vapor deposition (CVD). Briefly, the well-dispersed PAN nanofibers were sprayed onto the copper surface in an electrified thin liquid jet by electrospinning. Subsequently, CVD growth process induced the formation of graphene films using a PAN-solid source of carbon and a copper catalyst. Finally, crumpled and macroscopic graphene composite fibers were obtained from carbon nanofiber/graphene composite webs by self-assembly process in the deionized water. Temperature-dependent conduct behavior reveals that electron transport of the graphene composite fibers belongs to hopping mechanism and the typical electrical conductivity reaches 4.59 × 103 S m-1. These results demonstrated that the graphene composite fibers are promising for the next-generation flexible and wearable electronics.

Large-area, high-quality monolayer graphene from polystyrene at atmospheric pressure.

Graphene films have been attracting great interest owing to their unique physical properties. In this paper, we develop an efficient method to prepare large-area monolayer graphene (97.5% coverage) by atmospheric pressure chemical vapor deposition on Cu foils using polystyrene in a short time (3 min). Raman spectroscopy, transmission electron microscopy and scanning electron microscopy are employed to confirm the thickness and uniformity of the graphene films. Graphene films on glass substrates show high optical transmittance and electrical conductivity. Magnetic transport studies demonstrate that the as-grown monolayer graphene exhibits a high carrier mobility of 3395 cm2 V-1 s-1 at 25 K. On the basis of the analysis, it is concluded that our method is a simple, safe and versatile approach for the synthesis of monolayer graphene.

Directed growth of graphene nanomesh in purified argon via chemical vapor deposition.

Graphene nanomeshes (GNMs), new graphene nanostructures with tunable bandgaps, are potential building blocks for future electronic or photonic devices, and energy storage and conversion materials. In previous works, GNMs have been successfully prepared on Cu foils by the H2 etching effect. In this paper, we investigated the effect of Ar on the preparation of GNMs, and how the mean density and shape of them vary with growth time. In addition, scanning electron microscopy (SEM) and high resolution transmission electron microscopy (TEM) revealed the typical hexagonal structure of GNM. Atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS) indicated that large copper oxide nanoparticles produced by oxidization in purified Ar can play an essential catalytic role in preparing GNMs. Then, we exhibited the key reaction details for each growth process and proposed a growth mechanism of GNMs in purified Ar.

A high-performance organic lithium salt-doped OFET with the optical radical effect for photoelectric pulse synaptic simulation and neuromorphic memory learning.

Simulation of synaptic characteristics is essential for the application of organic field effect transistors (OFETs) in neural morphology. Although excellent performance, including bias stability and mobility, as well as photoelectric pulse synaptic simulation, has been achieved in SiO2-gated OFETs with PDVT-10 as an organic channel, there are relatively few studies on photoelectric pulse synaptic simulation of electrolyte-gated OFETs based on environmentally friendly and low-voltage operation. Herein, synaptic transistors based on organic semiconductors are reported to simulate the photoelectric pulse response by developing solution-based organic semiconductor PDVT-10, and polyvinyl alcohol (PVA) with an electric double layer (EDL) effect to act as a channel and gate dielectric layer, respectively, and organic lithium salt-doped PVA is used to enhance the EDL effect. The presence of electrical pulses in doped devices not only achieves basic electrical synaptic characteristics, but also significantly realizes the long-term characteristics, pain perception, memory and sensitization applications. Furthermore, the introduction of photoinitiator molecules into the channel layer leads to improved photosynaptic performances by using light-induced free radicals, and the photoelectric synergistic effect has been actualized by introducing heterojunction architecture. This work provides promising prospects for achieving photoelectric pulse modulation based on organic synaptic devices, which shows great potential for the development of artificial intelligence.

Acceleration of bone repairation by BMSCs overexpressing NGF combined with NSA and allograft bone scaffolds.

BACKGROUND: Repairation of bone defects remains a major clinical problem. Constructing bone tissue engineering containing growth factors, stem cells, and material scaffolds to repair bone defects has recently become a hot research topic. Nerve growth factor (NGF) can promote osteogenesis of bone marrow mesenchymal stem cells (BMSCs), but the low survival rate of the BMSCs during transplantation remains an unresolved issue. In this study, we investigated the therapeutic effect of BMSCs overexpression of NGF on bone defect by inhibiting pyroptosis. METHODS: The relationship between the low survival rate and pyroptosis of BMSCs overexpressing NGF in localized inflammation of fractures was explored by detecting pyroptosis protein levels. Then, the NGF+/BMSCs-NSA-Sca bone tissue engineering was constructed by seeding BMSCs overexpressing NGF on the allograft bone scaffold and adding the pyroptosis inhibitor necrosulfonamide(NSA). The femoral condylar defect model in the Sprague-Dawley (SD) rat was studied by micro-CT, histological, WB and PCR analyses in vitro and in vivo to evaluate the regenerative effect of bone repair. RESULTS: The pyroptosis that occurs in BMSCs overexpressing NGF is associated with the nerve growth factor receptor (P75NTR) during osteogenic differentiation. Furthermore, NSA can block pyroptosis in BMSCs overexpression NGF. Notably, the analyses using the critical-size femoral condylar defect model indicated that the NGF+/BMSCs-NSA-Sca group inhibited pyroptosis significantly and had higher osteogenesis in defects. CONCLUSION: NGF+/BMSCs-NSA had strong osteogenic properties in repairing bone defects. Moreover, NGF+/BMSCs-NSA-Sca mixture developed in this study opens new horizons for developing novel tissue engineering constructs.

Hierarchically porous metastable ß-Ag2WO4 hollow nanospheres: controlled synthesis and high photocatalytic activity.

Metastable materials have received extensive attention due to their unique physical and chemical properties which are different from those of the thermodynamically stable phase. However, the variety of reported metastable materials is still very limited owing to difficulties in the effective synthesis of pure metastable materials because they can easily transform into the corresponding stable phases. Therefore, it is crucial and a great challenge to explore new metastable materials with novel and fascinating functions. In this study, hierarchically porous metastable ß-Ag2WO4 hollow nanospheres with a diameter of 50-500 nm were prepared for the first time by a facile precipitation reaction between AgNO3 and Na2WO4 in the presence of poly(methacrylic acid) (PMAA). It was found that the PMAA not only provided a spherical soft template to induce the formation of hollow nanospheres but also worked as an inhibitor to prevent the phase transformation from thermodynamically unstable ß-Ag2WO4 to stable α-Ag2WO4 phase. The resultant metastable ß-Ag2WO4 hollow nanospheres show a larger specific surface area (165.5 m(2) g(-1)) owing to the hierarchically porous structure (micropores, mesopores, and macropores), resulting in a high photocatalytic performance for the decomposition of methyl orange and phenol aqueous solutions. The present work can provide some new insight into the smart design and preparation of other new metastable hollow materials, and the prepared metastable ß-Ag2WO4 hollow nanospheres have various potential applications in chemical reactors, drug-delivery carriers, solar cells, catalysis, and separation and purification fields.

Sensitive Silicon Nanowire Ultraviolet B Photodetector Induced by Leakage Mode Resonances.

Ultraviolet photodetectors (UVPDs) have played an important role both in civil and military applications. While various studies have shown that traditional UVPDs based on wide-band-gap semiconductors (WBSs) have excellent device performances, it is, however, undeniable that the practical application of WBS-based UVPDs is largely limited by the relatively high fabrication cost. In this work, we propose a new silicon nanowire (Si NW) UVPD that is very sensitive to UVB light illumination. The Si NWs with a diameter of about 36 nm are fabricated by a metal-assisted chemical etching method. Performance analysis revealed that the Si NW device was only sensitive to UVB light and almost blind to illumination in the visible and near-infrared regions. Such abnormal spectral selectivity was associated with the leakage mode resonances (LMRs) of the small diameter, according to our theoretical simulation. Under 300 nm illumination, the responsivity, external quantum efficiency, and specific detectivity were estimated to be 10.2 AW-1, 4.22 × 103%, and 2.14 × 1010 Jones, respectively, which were comparable to or even higher than those of some WBS-based UVPDs. These results illustrate that the small dimension Si NWs are potential building blocks for low-cost and high-performance UVPDs in the future.

Filterless Discrimination of Wavelengths in the Range from Ultraviolet to Near-Infrared Light Using Two PdSe2/Thin Si/PdSe2 Heterojunction Photodetectors.

In this study, we present a wavelength sensor that is capable of distinguishing the spectrum in the range from ultraviolet (UV) to near-infrared (NIR) light. The filterless device is composed of two horizontally stacking PdSe2/20 µm Si/PdSe2 heterojunction photodetectors with a photovoltaic (PV) behavior, which makes it possible for the device to work at 0 bias voltage. Due to the relatively small thickness of Si and the wavelength-dependent absorption coefficient, the two PdSe2/20 µm Si/PdSe2 photodetectors according to theoretical simulation display a sharp contrast in distribution of the photoabsorption rate. As a result, the photocurrents of both photodetectors evolve in completely different ways with increasing wavelengths, leading to a monotonic decrease in the photocurrent ratio from 6800 to 22 when the wavelength gradually increases from 265 to 1050 nm. The corresponding relationship between both the photocurrent ratio and wavelength can be easily described by the monotonic function, which can help to precisely determine the wavelength in the range from 265 to 1050 nm, with an average relative error less than ±1.6%. It is also revealed that by slightly revising the monotonic function, the wavelength in other different temperatures can also be estimated.

Detection of wavelength in the range from ultraviolet to near infrared light using two parallel PtSe2/thin Si Schottky junctions.

A wavelength sensor as a representative optoelectronic device plays an important role in many fields including visible light communication, medical diagnosis, and image recognition. In this study, a wavelength-sensitive detector with a new operation mechanism was reported. The as-proposed wavelength sensor which is composed of two parallel PtSe2/thin Si Schottky junction photodetectors is capable of distinguishing wavelength in the range from ultraviolet to near infrared (UV-NIR) light (265 to 1050 nm), in that the relationship between the photocurrent ratio of both photodetectors and incident wavelength can be numerically described by a monotonic function. The unique operation mechanism of the thin Si based wavelength sensor was unveiled by theoretical simulation based on Synopsys Sentaurus Technology Computer Aided Design (TCAD). Remarkably, the wavelength sensor has an average absolute error of ±4.05 nm and an average relative error less than ±0.56%, which are much better than previously reported devices. What is more, extensive analysis was performed to reveal how and to what extent the working temperature and incident light intensity, and the thickness of the PtSe2 layer will influence the performance of the wavelength sensor.

Leaky Mode Resonance-Induced Sensitive Ultraviolet Photodetector Composed of Graphene/Small Diameter Silicon Nanowire Array Heterojunctions.

Ultraviolet photodetectors (UVPDs) based on wide band gap semiconductors (WBSs) are important for various civil and military applications. However, the relatively harsh preparation conditions and the high cost are unfavorable for commercialization. In this work, we proposed a non-WBS UVPD by using a silicon nanowire (SiNW) array with a diameter of 45 nm as building blocks. Device analysis revealed that the small diameter SiNW array covered with monolayer graphene was sensitive to UV light but insensitive to both visible and infrared light illumination, with a typical rejection ratio of 25. Specifically, the responsivity, specific detectivity, and external quantum efficiency under 365 nm illumination were estimated to be 0.151 A/W, 1.37 × 1012 Jones, and 62%, respectively, which are comparable to or even better than other WBS UVPDs. Such an abnormal photoelectrical characteristic is related to the HE1m leaky mode resonance (LMR), which is able to shift the peak absorption spectrum from near-infrared to UV regions. It is also revealed that this LMR is highly dependent on the diameter and the period of the SiNW array. These results show narrow band gap semiconductor nanostructures as promising building blocks for the assembly of sensitive UV photodetectors, which are very important for various optoelectronic devices and systems.

Insights into protease sequence similarities by comparing substrate sequences and phylogenetic dynamics.

Based on substrate sequences, we proposed a novel method for comparing sequence similarities among 68 proteases compiled from the MEROPS online database. The rank vector was defined based on the frequencies of amino acids at each site of the substrate, aiming to eliminate the different order variances of magnitude between proteases. Without any assumption on homology, a protease specificity tree is constructed with a striking clustering of proteases from different evolutionary origins and catalytic types. Compared with other methods, almost all the homologous proteases are clustered in small branches in our phylogenetic tree, and the proteases belonging to the same catalytic type are also clustered together, which may reflect the genetic relationship among the proteases. Meanwhile, certain proteases clustered together may play a similar role in key pathways categorized using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Consequently, this method can provide new insights into the shared similarities among proteases. This may inspire the design and development of targeted drugs that can specifically regulate protease activity.

Direct Tellurization of Pt to Synthesize 2D PtTe2 for High-Performance Broadband Photodetectors and NIR Image Sensors.

Platinum telluride (PtTe2) has garnered significant research enthusiasm owing to its unique characteristics. However, large-scale synthesis of PtTe2 toward potential photoelectric and photovoltaic application has not been explored yet. Herein, we report direct tellurization of Pt nanofilms to synthesize large-area PtTe2 films and the influence of growth conditions on the morphology of PtTe2. Electrical analysis reveals that the as-grown PtTe2 films exhibit typical semimetallic behavior, which is in agreement with the results of first-principles density functional theory (DFT) simulation. Moreover, the combination of multilayered PtTe2 and Si results in the formation of a PtTe2/Si heterojunction, exhibiting an obvious rectifying effect. Moreover, the PtTe2-based photodetector displays a broadband photoresponse to incident radiation in the range of 200-1650 nm, with the maximum photoresponse at a wavelength of ∼980 nm. The R and D* of the PtTe2-based photodetector are found to be 0.406 A W-1 and 3.62 × 1012 Jones, respectively. In addition, the external quantum efficiency is as high as 32.1%. On the other hand, the response time of τrise and τfall is estimated to be 7.51 and 36.7 µs, respectively. Finally, an image sensor composed of a 8 × 8 PtTe2-based photodetector array was fabricated, which can record five near-infrared (NIR) images under 980 nm with a satisfying resolution. The result demonstrates that the as-prepared PtTe2 material will be useful for application in NIR optoelectronics.