A Coupled System of Ni3S2 and Rh Complex with Biomimetic Function for Electrocatalytic 1,4-NAD(P)H Regeneration.

NAD(P)H cofactor is a critical energy and electron carrier in biocatalysis and photosynthesis, but the artificial reduction of NAD(P)+ to regenerate bioactive 1,4-NAD(P)H with both high activity and selectivity is challenging. Herein, we found that a coupled system of a Ni3S2 electrode and a Rh complex in an electrolyte (denoted as Ni3S2-Rh) can catalyze the reduction of NAD(P)+ to 1,4-NAD(P)H with superior activity and selectivity. The optimized selectivity in 1,4-NADH can be up to 99.1%, much higher than that for Ni3S2 (80%); the normalized activity of Ni3S2-Rh is about 5.8 times that of Ni3S2 and 13.2 times that of the Rh complex. The high performance of Ni3S2-Rh is attributed to the synergistic effect between metal sulfides and Rh complex. The NAD+ reduction reaction proceeds via a concerted electron-proton transfer (CEPT) mechanism in the Ni3S2-Rh system, in which Ni3S2 acts as a proton and electron-transfer mediator to accelerate the formation of Rh hydride (Rh-H), and then the Rh-H regioselectively transfers the hydride to NAD+ to form 1,4-NADH. The artificial system Ni3S2-Rh essentially mimics the functions of ferredoxin-NADP+ reductase in nature.

Hydrogel-Based Biosensors for Bacterial Infections.

Hydrogels are known to have the advantages such as good biodegradability, biocompatibility, and easy functionalization, making them ideal candidates for biosensors. Hydrogel-based biosensors that respond to bacteria-induced microenvironmental changes such as pH, enzymes, antigens, etc., or directly interact with bacterial surface receptors, can be applied for early diagnosis of bacterial infections, providing information for timely treatment while avoiding antibiotic abuse. Furthermore, hydrogel biosensors capable of both bacteria diagnosis and treatment will greatly facilitate the development of point-of-care monitoring of bacterial infections. In this review, the recent advancement of hydrogel-based biosensors for bacterial infection is summarized and discussed. First, the biosensors based on pH-sensitive hydrogels, bacterial-specific secretions-sensitive hydrogels, and hydrogels directly in contact with bacterial surfaces are presented. Next, hydrogel biosensors capable of detecting bacterial infection in the early stage followed by immediate on-demand treatment are discussed. Finally, the challenges and future development of hydrogel biosensors for bacterial infections are proposed.

Natural Underwater Bioadhesive Offering Cohesion Modulation via Hydrogen Bond Disruptor: A Highly Injectable and in Vivo Stable Remedy for Gastric Ulcer Resolution.

Injectable bioadhesives are attractive for managing gastric ulcers through minimally invasive procedures. However, the formidable challenge is to develop bioadhesives that exhibit high injectability, rapidly adhere to lesion tissues with fast gelation, provide reliable protection in the harsh gastric environment, and simultaneously ensure stringent standards of biocompatibility. Here, a natural bioadhesive with tunable cohesion is developed based on the facile and controllable gelation between silk fibroin and tannic acid. By incorporating a hydrogen bond disruptor (urea or guanidine hydrochloride), the inherent network within the bioadhesive is disturbed, inducing a transition to a fluidic state for smooth injection (injection force <5 N). Upon injection, the fluidic bioadhesive thoroughly wets tissues, while the rapid diffusion of the disruptor triggers instantaneous in situ gelation. This orchestrated process fosters the formed bioadhesive with durable wet tissue affinity and mechanical properties that harmonize with gastric tissues, thereby bestowing long-lasting protection for ulcer healing, as evidenced through in vitro and in vivo verification. Moreover, it can be conveniently stored (≥3 m) postdehydration. This work presents a promising strategy for designing highly injectable bioadhesives utilizing natural feedstocks, avoiding any safety risks associated with synthetic materials or nonphysiological gelation conditions, and offering the potential for minimally invasive application.

Supramolecular Photonic Hydrogel for High-Sensitivity Alkaline Phosphatase Detection via Synergistic Driving Force.

Structurally-colored photonic hydrogels which are fabricated by introducing hydrogels into thin films or photonic crystal structures are promising candidates for biosensing. Generally, the design of photonic hydrogel biosensors is based on the sensor-analyte interactions induced charge variation within the hydrogel matrix, or chemically grafting binding sites onto the polymer chains, to achieve significant volume change and color variation of the photonic hydrogel. However, relatively low anti-interference capability or complicated synthesis hinder the facile and low-cost fabrication of high-performance photonic hydrogel biosensors. Here, a facilely prepared supramolecular photonic hydrogel biosensor is developed for high-sensitivity detection of alkaline phosphatase (ALP), which is an extensively considered clinical biomarker for a variety of diseases. Responding to ALP results in the broken supramolecular crosslinking and thus increased lattice distancing of the photonic hydrogel driven by synergistic repulsive force between nanoparticles embedded in photonic crystal structure and osmotic swelling pressure. The biosensor shows sensitivity of 7.3 nm spectral shift per mU mL-1 ALP, with detection limit of 0.52 mU mL-1 . High-accuracy colorimetric detection can be realized via a smartphone, promoting point-of-care sensing and timely diagnosis of related pathological conditions.

Self-Organized Spatiotemporal Mineralization of Hydrogel: A Simulant of Osteon.

Nature creates fascinating self-organized spatiotemporal patterns through the delicate control of reaction-diffusion dynamics. As the primary unit of cortical bone, osteon has concentric lamellar architecture, which plays a crucial role in the mechanical and physiological functions of bone. However, it remains a great challenge to fabricate the osteon-like structure in a natural self-organization way. Taking advantage of the nonequilibrium reaction in hydrogels, a simple mineralization strategy to closely mimic the formation of osteon in a mild physiological condition is developed. By constructing two reverse concentration gradients of ions from periphery to interior of cylindrical hydrogel, spatiotemporal self-organization of calcium phosphate in concentric rings is generated. It is noteworthy that minerals in different layers possess diverse contents and crystalline phases, which further guide the adhesion and spread of osteoblasts on these patterns, resembling the architecture and cytological behavior of osteon. Besides, theoretical data indicates the predominate role of ion concentrations and pH values of solution, in good accordance with experimental results. Independent of precise instruments, this lifelike method is easily obtained, cost-efficient, and effectively imitates the mineral deposition in osteon from a physiochemical view. The strategy may be expanded to develop other functional material patterns via spatiotemporal self-organization.

Charge Separation by Creating Band Bending in Metal-Organic Frameworks for Improved Photocatalytic Hydrogen Evolution.

Metal-organic frameworks (MOFs) have been intensively studied as a class of semiconductor-like materials in photocatalysis. However, band bending, which plays a crucial role in semiconductor photocatalysis, has not yet been demonstrated in MOF photocatalysts. Herein, a representative MOF, MIL-125-NH2 , is integrated with the metal oxides (MoO3 and V2 O5 ) that feature appropriate work functions and energy levels to afford the corresponding MOF composites. Surface photovoltage results demonstrate band bending in the MOF composites, which gives rise to the built-in electric field of MIL-125-NH2 , boosting the charge separation. As a result, the MOF composites present 56 and 42 times higher activities, respectively, compared to the pristine MOF for photocatalytic H2 production. Upon depositing Pt onto the MOF, ∼6 times higher activity is achieved. This work illustrates band bending of MOFs for the first time, supporting their semiconductor-like nature, which would greatly promote MOF photocatalysis.

A new 3D model for genotoxicity assessment: EpiSkin™ Micronucleus Assay.

The European Regulation on Cosmetics (no. 1223/2009) has prohibited the use of animals in safety testing since March 2009 for ingredients used in cosmetics. Irreversible events at the chromosome level (clastogenesis and aneugenesis) are commonly evaluated by scoring either micronuclei or chromosome aberrations using cell-based genotoxicity assays. Like most in vitro genotoxicity assays, the 2D in vitro micronucleus assay exhibits a poor specificity and does not mimic the dermal route. To address these limitations, the current project aims to develop and validate a 3D micronucleus assay using the EpiSkin™ model. This project is scientifically supported by the Cosmetics Europe Genotoxicity Task Force. In a first step, two key criteria for the development of micronucleus assay, namely, the sufficient yield of cells from the EpiSkin™ model and an acceptable proliferation rate of the basal layer, were assessed and demonstrated. Subsequently, six chemicals (vinblastine, n-ethylnitrosourea, ß-butyrolactone, 2-acetylaminofluorene, 2,4-dichlorophenoland d-limonene) were evaluated in the EpiSkin™ Micronucleus Assay. At least two independent experiments using 48- and 72-h incubations were performed for each chemical. Results showed good inter-experimental reproducibility, as well as the correct identification of all six tested chemicals. The metabolism of 2-acetylaminofluorene on the EpiSkin™ model was also investigated and confirmed by the formation of an intermediate metabolite (2-aminofluorene). These preliminary results from the EpiSkin™ Micronucleus Assay indicate that it is a promising in vitro assay for assessing genotoxicity. The availability and suitability of this test method contribute significantly to the development of non-animal testing methods in China and its impact on the worldwide field.

Interfacial Microenvironment Modulation Boosting Electron Transfer between Metal Nanoparticles and MOFs for Enhanced Photocatalysis.

Interfacial electron transfer between cocatalyst and photosensitizer is key in heterogeneous photocatalysis, yet the underlying mechanism remains subtle and unclear. Surfactant coated on the metal cocatalysts, greatly modulating the microenvironment of catalytic sites, is largely ignored. Herein, a series of Pt co-catalysts with modulated microenvironments, including polyvinylpyrrolidone (PVP) capped Pt nanoparticles (denoted as PtPVP ), Pt with partially removed PVP (PtrPVP ), and clean Pt without PVP (Pt), were encapsulated into a metal-organic framework (MOF), UiO-66-NH2 , to afford PtPVP @UiO-66-NH2 , PtrPVP @UiO-66-NH2 , and Pt@UiO-66-NH2 , respectively, for photocatalytic hydrogen production. The PVP appears to have a negative influence on the interfacial electron transfer between Pt and the MOF. Compared with PtPVP @UiO-66-NH2 , the removal of interfacial PVP improves the sluggish kinetics of electron transfer, boosting photocatalytic hydrogen production.

Diagnostic Accuracy of Intestinal Fatty Acid Binding Protein for Acute Intestinal Ischemia: a Systematic Review and Meta-Analysis.

BACKGROUND: Some studies have investigated the diagnostic value of intestinal fatty acid binding protein (I-FABP) for acute intestinal ischemia (II), but the results were not always consistent. Therefore, we performed a systematic review and meta-analysis to determine the diagnostic accuracy of I-FABP for II. METHODS: Publications included in the PubMed and EMBASE before April 7, 2019 were retrieved to identify studies investigating the diagnostic accuracy of I-FABP for II. The Revised Tool for the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) was used to assess the quality of eligible studies. Diagnostic accuracy of I-FABP in all eligible studies was pooled by a bivariate model. Summary receiver operating characteristic (ROC) curves (AUC) were constructed to calculate the overall diagnostic accuracy of I-FABP. RESULTS: A total of 10 studies with 1,265 (219 IIs and 1,046 controls) subjects were included in this systematic review and meta-analysis. The major design weaknesses of included studies were patient selection bias. The overall diagnostic sensitivity, specificity, and AUC of I-FABP were 0.75 (95% CI: 0.68 - 0.82), 0.85 (95% CI: 0.74 - 0.92), and 0.82 (95% CI: 0.79 - 0.86), respectively. In patients with acute abdominal pain, the sensitivity, specificity, and AUC of I-FABP were 0.71 (95% CI: 0.59 - 0.81), 0.89 (95% CI: 0.69 - 0.97) and 0.80 (95% CI: 0.76 - 0.83), respectively. CONCLUSIONS: I-FABP has moderate diagnostic accuracy for II. Due the patient selection bias of available studies, further studies with rigorous design are needed to evaluate the diagnostic accuracy of I-FABP for II.

Incorporating Transition-Metal Phosphides Into Metal-Organic Frameworks for Enhanced Photocatalysis.

Metal-organic frameworks (MOFs) have been shown to be an excellent platform in photocatalysis. However, to suppress electron-hole recombination, a Pt cocatalyst is usually inevitable, especially in photocatalytic H2 production, which greatly limits practical application. Herein, for the first time, monodisperse, small-size, and noble-metal-free transitional-metal phosphides (TMPs; for example, Ni2 P, Ni12 P5 ), are incorporated into a representative MOF, UiO-66-NH2 , for photocatalytic H2 production. Compared with the parent MOF and their physical mixture, both TMPs@MOF composites display significantly improved H2 production rates. Thermodynamic and kinetic studies reveal that TMPs, behaving similar ability to Pt, greatly accelerate the linker-to-cluster charge transfer, promote charge separation, and reduce the activation energy of H2 production. Significantly, the results indicate that Pt is thermodynamically favorable, yet Ni2 P is kinetically preferred for H2 production, accounting for the higher activity of Ni2 P@UiO-66-NH2 than Pt@UiO-66-NH2 .

A Hydrogen Farm Strategy for Scalable Solar Hydrogen Production with Particulate Photocatalysts.

Scalable solar hydrogen production by water splitting using particulate photocatalysts is promising for renewable energy utilization. However, photocatalytic overall water splitting is challenging owing to slow water oxidation kinetics, severe reverse reaction, and H2 /O2 gas separation. Herein, mimicking nature photosynthesis, a practically feasible approach named Hydrogen Farm Project (HFP) is presented, which is composed of solar energy capturing and hydrogen production subsystems integrated by a shuttle ion loop, Fe3+ /Fe2+ . Well-defined BiVO4 crystals with precisely tuned {110}/{010} facets are ideal photocatalysts to realize the HFP, giving up to 71 % quantum efficiency for photocatalytic water oxidation and full forward reaction with nearly no reverse reaction. An overall solar-to-chemical efficiency over 1.9 % and a solar-to-hydrogen efficiency exceeding 1.8 % could be achieved. Furthermore, a scalable HFP panel for solar energy storage was demonstrated under sunlight outdoors.

A glassy carbon electrode modified with molecularly imprinted poly(aniline boronic acid) coated onto carbon nanotubes for potentiometric sensing of sialic acid.

A potentiometric sensor for sialic acid (SA) was developed based on molecular imprinting technique. The sensor was fabricated by modifying carbon nanotubes (CNT) and an SA-imprinted poly(aniline boronic acid) (PABA) film on a glassy carbon electrode (GCE). The detection strategy capitalizes on the change of electrochemical potential resulting from boronic acid-SA interaction. The imprinted PABA combines the functions of SA-binding boronic acid groups and the imprinting effect, thus endowing it with both chemical and sterical recognition capability. The imprint factor (IF, compared to a non-molecularly imprinted polymer) is 1.74. The sensor can well differentiate SA from its analogs at physiological pH values and has a linear potentiometric response (R2 = 0.998) in 80 µM to 8.2 mM SA concentrations range with a detection limit of 60 µM (at S/N = 3). The sensor was applied to the determination of SA in serum samples and gave recoveries between 93% and 105%. Graphical abstract Schematic presentation of the fabrication of a sialic acid (SA) imprinted poly(aniline boronic acid) (PABA)/CNT modified electrode. The electrode can well differentiate SA from its analogs at physiological pH and determine SA in human serum samples with satisfactory recoveries of 93%-105%.

Mimicking the Key Functions of Photosystem II in Artificial Photosynthesis for Photoelectrocatalytic Water Splitting.

It has been anticipated that learning from nature photosynthesis is a rational and effective way to develop artificial photosynthesis system, but it is still a great challenge. Here, we assembled a photoelectrocatalytic system by mimicking the functions of photosystem II (PSII) with BiVO4 semiconductor as a light harvester protected by a layered double hydroxide (NiFeLDH) as a hole storage layer, a partially oxidized graphene (pGO) as biomimetic tyrosine for charge transfer, and molecular Co cubane as oxygen evolution complex. The integrated system exhibited an unprecedentedly low onset potential (0.17 V) and a high photocurrent (4.45 mA cm-2), with a 2.0% solar to hydrogen efficiency. Spectroscopic studies revealed that this photoelectrocatalytic system exhibited superiority in charge separation and transfer by benefiting from mimicking the key functions of PSII. The success of the biomimetic strategy opened up new ways for the rational design and assembly of artificial photosynthesis systems for efficient solar-to-fuel conversion.

Efficient Hole Extraction from a Hole-Storage-Layer-Stabilized Tantalum Nitride Photoanode for Solar Water Splitting.

One of the major hurdles that impedes the practical application of photoelectrochemical (PEC) water splitting is the lack of stable photoanodes with low onset potentials. Here, we report that the Ni(OH)x/MoO3 bilayer, acting as a hole-storage layer (HSL), efficiently harvests and stores holes from Ta3N5, resulting in at least 24 h of sustained water oxidation at the otherwise unstable Ta3N5 electrode and inducing a large cathodic shift of ≈600 mV in the onset potential of the Ta3N5 electrode.

Wettability-regulated extracellular electron transfer from the living organism of Shewanella loihica PV-4.

C-type cytochromes located on the outer membrane (OMCs) of genus Shewanella act as the main redox-active species to mediate extracellular electron transfer (EET) from the inside of the outer membrane to the external environment: the central challenge that must be met for successful EET. The redox states of OMCs play a crucial role in dictating the rate and extent of EET. Here, we report that the surface wettability of the electrodes strongly influences the EET activity of living organisms of Shewanella loihica PV-4 at a fixed external potential: the EET activity on a hydrophilic electrode is more than five times higher than that on a hydrophobic one. We propose that the redox state of OMCs varies significantly at electrodes with different wettability, resulting in different EET activities.

Solar-to-hydrogen efficiency exceeding 2.5% achieved for overall water splitting with an all earth-abundant dual-photoelectrode.

The solar-to-hydrogen (STH) efficiency of a traditional mono-photoelectrode photoelectrochemical water splitting system has long been limited as large external bias is required. Herein, overall water splitting with STH efficiency exceeding 2.5% was achieved using a self-biased photoelectrochemical-photovoltaic coupled system consisting of an all earth-abundant photoanode and a Si-solar-cell-based photocathode connected in series under parallel illumination. We found that parallel irradiation mode shows higher efficiency than tandem illumination especially for photoanodes with a wide light absorption range, probably as the driving force for water splitting reaction is larger and the photovoltage loss is smaller in the former. This work essentially takes advantage of a tandem solar cell which can enhance the solar-to-electricity efficiency from another point of view.

A tantalum nitride photoanode modified with a hole-storage layer for highly stable solar water splitting.

Photoelectrochemical (PEC) water splitting is an ideal approach for renewable solar fuel production. One of the major problems is that narrow bandgap semiconductors, such as tantalum nitride, though possessing desirable band alignment for water splitting, suffer from poor photostability for water oxidation. For the first time it is shown that the presence of a ferrihydrite layer permits sustainable water oxidation at the tantalum nitride photoanode for at least 6 h with a benchmark photocurrent over 5 mA cm(-2) , whereas the bare photoanode rapidly degrades within minutes. The remarkably enhanced photostability stems from the ferrihydrite, which acts as a hole-storage layer. Furthermore, this work demonstrates that it can be a general strategy for protecting narrow bandgap semiconductors against photocorrosion in solar water splitting.

Bioinspired Multiscale Mineralization: From Fundamentals to Potential Applications.

The wondrous and imaginative designs of nature have always been an inexhaustible treasure trove for material scientists. Throughout the long evolutionary process, biominerals with hierarchical structures possess some specific advantages such as outstanding mechanical properties, biological functions, and sensing performances, the formation of which (biomineralization) is delicately regulated by organic component. Provoked by the subtle structures and profound principles of nature, bioinspired functional minerals can be designed with the participation of organic molecules. Because of the designable morphology and functions, multiscale mineralization has attracted more and more attention in the areas of medicine, chemistry, biology, and material science. This review provides a summary of current advancements in this extending topic. The mechanisms underlying mineralization is first concisely elucidated. Next, several types of minerals are categorized according to their structural characteristic, as well as the different potential applications of these materials. At last, a comprehensive overview of future developments for bioinspired multiscale mineralization is given. Concentrating on the mechanism of fabrication and broad application prospects of multiscale mineralization, the hope is to provide inspirations for the design of other functional materials.

Advances in biomimetic nanomaterial delivery systems: harnessing nature's inspiration for targeted drug delivery.

The properties of nanomaterials make them promising and advantageous for use in drug delivery systems, but challenges arise from the immune system's recognition of exogenous nanoparticles, leading to their clearance and reduced targeting efficiency. Drawing inspiration from nature, this paper explores biomimetic strategies to transform recognizable nanomaterials into a "camouflaged state." The focal point of this paper is the exploration of bionic nanoparticles, with a focus on cell membrane-coated nanoparticles. These biomimetic structures, particularly those mimicking red blood cells (RBCs), white blood cells (WBCs), platelets, and cancer cells, demonstrate enhanced drug delivery efficiency and prolonged circulation. This article underscores the versatility of these biomimetic structures across diverse diseases and explores the use of hybrid cell membrane-coated nanoparticles as a contemporary trend. This review also investigated exosomes and protein bionic nanoparticles, emphasizing their potential for specific targeting, immune evasion, and improved therapeutic outcomes. We expect that this continued development based on biomimetic nanomaterials will contribute to the efficiency and safety of disease treatment.

A Drop-By-Drop Self-Assembled All-Natural Hydrogel as a Desensitizer for Rapid and Enduring Management of Dentin Hypersensitivity.

Dentin hypersensitivity (DH) is a prevalent dental condition arising from the exposure of dentin tubules (DTs), leading to discomfort upon external stimuli. However, achieving swift and profound occlusion of these exposed DTs for immediate and enduring relief remains challenging due to the intricate dentin structure and oral environment. Herein, a pioneering and facile drop-by-drop strategy involving an in situ generated natural supramolecular hydrogel formed by self-assembling silk fibroin (SF) and tannic acid (TA) within the narrow DT space is proposed. When SF and TA aqueous solutions are applied successively to exposed dentin, they penetrate deeply within DTs and coassemble into compact gels, robustly adhering to DT walls. This yields a rapid and compact occlusion effect with an unprecedented depth exceeding 250 µm, maintaining stable occlusion efficacy even under rigorous in vitro and in vivo erosion and friction conditions for no less than 21 days. Furthermore, the biocompatibility and effective occlusion properties are verified through cell studies in simulated oral settings and an in vivo rabbit model. This study, for the first time, demonstrates the translational potential of hydrogel-based desensitizers in treating DH with prompt action, superior occlusion depth and enduring treatment benefits, holding promise as clinical-friendly restorative solutions for delicate-structured biosystems.