Selenide-linked polydopamine-reinforced hybrid hydrogels with on-demand degradation and light-triggered nanozyme release for diabetic wound healing

BACKGROUND

Multifunctional hydrogels with controllable degradation and drug release have attracted extensive attention in diabetic wound healing. This study focused on the acceleration of diabetic wound healing with selenide-linked polydopamine-reinforced hybrid hydrogels with on-demand degradation and light-triggered nanozyme release.

METHODS

Herein, selenium-containing hybrid hydrogels, defined as DSeP@PB, were fabricated via the reinforcement of selenol-end capping polyethylene glycol (PEG) hydrogels by polydopamine nanoparticles (PDANPs) and Prussian blue nanozymes in a one-pot approach in the absence of any other chemical additive or organic solvent based on diselenide and selenide bonding-guided crosslinking, making them accessible for large-scale mass production.

RESULTS

Reinforcement by PDANPs greatly increases the mechanical properties of the hydrogels, realizing excellent injectability and flexible mechanical properties for DSeP@PB. Dynamic diselenide introduction endowed the hydrogels with on-demand degradation under reducing or oxidizing conditions and light-triggered nanozyme release. The bioactivity of Prussian blue nanozymes afforded the hydrogels with efficient antibacterial, ROS-scavenging and immunomodulatory effects, which protected cells from oxidative damage and reduced inflammation. Further animal studies indicated that DSeP@PB under red light irradiation showed the most efficient wound healing activity by stimulating angiogenesis and collagen deposition and inhibiting inflammation.

CONCLUSION

The combined merits of DSeP@PB (on-demand degradation, light-triggered release, flexible mechanical robustness, antibacterial, ROS-scavenging and immunomodulatory capacities) enable its high potential as a new hydrogel dressing that can be harnessed for safe and efficient therapeutics for diabetic wound healing.

PHMB modified photothermally triggered nitric oxide release nanoplatform for precise synergistic therapy of wound bacterial infections

Bacterial infection has been considered as a significant obstacle for wound healing. Nitric oxide (NO), as a novel alternative for antibiotics, has emerged as a promising antibacterial agent. However, the precise spatiotemporal controlled release of NO still remains a major challenge. Herein, a near-infrared (NIR) light triggered NO release nanoplatform (designated as PB-NO@PDA-PHMB) with enhanced broad-spectrum antibacterial and anti-biofilm properties was constructed. Given that PB-NO@PDA-PHMB has strong absorption in the NIR region and exhibits excellent photothermal effect, it can rapidly trigger NO release by NIR irradiation. PB-NO@PDA-PHMB can effectively contact and capture bacteria, and then exhibit synergistic effect of photothermal and gas therapy. In vitro and in vivo experiments indicated that PB-NO@PDA-PHMB exhibited excellent biocompatibility, satisfactory synergistic antibacterial efficacy and the capability of accelerating wound healing. Under NIR irradiation (808 nm, 1 W cm^-2, 7 min), PB-NO@PDA-PHMB (80 μg mL^-1) achieved 100% bactericidal activity against both Gram-negative bacteria Escherichia coli (E. coli) and Gram-positive bacteria Staphyloccocus aureus (S. aureus), removed 58.94% of S. aureus biofilm. Therefore, this all-in-one antibacterial nanoplatform with high NIR responsiveness provides a promising antibiotic-free strategy for bacterial infection treatment.

Bone marrow iron scoring in healthy and clinically ill dogs with and without evidence of iron-restricted erythropoiesis

BACKGROUND

There are few reports in dogs that have evaluated the utility of semi-quantitative scoring of bone marrow iron stores in conjunction with reticulocyte hemoglobin (CHr) to identify iron-restricted erythropoiesis due to absolute iron deficiency or iron sequestration.

OBJECTIVES

An established system for scoring iron stores in human bone marrow samples was applied to dogs. The objectives were to evaluate interobserver agreement (Κ_ω ), determine marrow iron scores in dogs without detectable hematologic abnormalities, and assess combined interpretation of iron scores and CHr to evaluate for iron-restricted erythropoiesis.

METHODS

Four blinded observers independently scored iron in 139 Prussian blue-stained canine marrow samples from 0 (none) to 6 (very heavy), including healthy controls (n = 12), clinically ill dogs with (n = 100) and without (n = 16) detectable hematologic abnormalities, and dogs with experimental nutritional iron deficiency (n = 11). Additional medical record data were available for 118 dogs to evaluate for other evidence of iron deficiency (abnormal CHr, RBC indices, serum iron variables, external blood loss, or nutritional deficiencies).

RESULTS

Mean Κ_ω was 0.69 (substantial agreement) for all samples but was 0.44 (moderate agreement) for samples with iron scores <3, indicating distinguishing scores 0-2 may not be reliable. Dogs without detectable hematologic abnormalities had scores from 3-5. Dogs with scores <3 and decreased CHr often had more indicators of iron deficiency vs dogs only having low iron scores or low CHr.

CONCLUSIONS

Evaluation of dogs with marrow iron score <3 for external blood loss or nutritional deficiencies is likely clinically worthwhile, particularly if there is also decreased CHr.

Oriented Assembled Prussian Blue Analogue Framework for Confined Catalytic Decomposition of Ammonium Perchlorate

The design of highly dispersed active sites of hollow materials and unique contact behavior with the components to be catalyzed provide infinite possibilities for exploring the limits of catalyst capacity. In this study, the synthesis strategy of highly open 3-dimensional frame structure Prussian blue analogues (CoFe-PBA) was explored through structure self-transformation, which was jointly guided by template mediated epitaxial growth, restricted assembly and directional assembly. Additionally, good application prospect of CoFe-PBA as combustion catalyst was discussed. The results show that unexpected thermal decomposition behavior can be achieved by limiting AP(ammonium perchlorate) to the framework of CoFe-PBA. The high temperature decomposition stage of AP can be advanced to 283.6 °C and the weight loss rate can reach 390.03% min^-1 . In-situ monitoring shows that CoFe-PBA can accelerate the formation of NO and NO₂ . The calculation of reaction kinetics proved that catalytic process was realized by increasing the nucleation factor. On this basis, the catalytic mechanism of CoFe-PBA on the thermal decomposition of AP was discussed, and the possible interaction process between AP and CoFe-PBA during heating was proposed. At the same time, another interesting functional behavior to prevent AP from caking was discussed.

Bio-inspired nanozyme with ultra-thin Fe-Bi2O2S nanosheets for in-situ amplified photoelectrochemical immunoassay of cancer-related protein

A Fe-loaded Bi₂O₂S nanosheet photoanode serving as photoelectric biomonitoring platform for the detection of prostate-specific antigen (PSA) using biologically inspired prussian nanoparticle (PB)-catalyzed biocatalytic precipitation strategy was developed. Primarily, the signal probe PB-mAb₂ obtained by electrostatic adsorption was immobilized on a microplate in the presence of target PSA, and 4-chloro-1-naphthol (4-CN) was oxidized to benzo-4-chloro-hexadienone (4-CD) with the assistance of exogenous hydrogen peroxide, which was generated by a large number of hydroxyl radicals catalyzed by PB. The generated 4-CD showed strongly low conductivity characteristics to burst the photocurrent of highly photoactive Fe-Bi₂O₂S photoanode. The split incubation reaction could be suitable for high volume and low-cost rapid detection. A dynamic response range of 0.1-100 ng mL^-1 with a limit of detection of 34.2 pg mL^-1 was achieved with the sensor based on a photoelectric sensing platform and a biomimetic catalytic precipitation reaction. Equally important, the sensor also showed good potential in the detection of real samples compared to commercially available ELISA kits. In conclusion, this work provides a fresh scheme for the development of sensitive biosensors through a bio-inspired catalytic strategy of versatility and a photoanode coupling with high photoelectric activity.

Prussian blue nanozymes coated with Pluronic attenuate inflammatory osteoarthritis by blocking c-Jun N-terminal kinase phosphorylation

Osteoarthritis (OA) is a degenerative joint disorder associated with inflammation, functional disability, and high socioeconomic costs. The development of effective therapies against inflammatory OA has been limited owing to its complex and multifactorial nature. The efficacy of Prussian blue nanozymes coated with Pluronic (PPBzymes), US Food and Drug Administration-approved components, and their mechanisms of action have been described in this study, and PPBzymes have been characterized as a new OA therapeutic. Spherical PPBzymes were developed via nucleation and stabilization of Prussian blue inside Pluronic micelles. A uniformly distributed diameter of approximately 204 nm was obtained, which was maintained after storage in an aqueous solution and biological buffer. This indicates that PPBzymes are stable and could have biomedical applications. In vitro data revealed that PPBzymes promote cartilage generation and reduce cartilage degradation. Moreover, intra-articular injections with PPBzymes into mouse joints revealed their long-term stability and effective uptake into the cartilage matrix. Furthermore, intra-articular PPBzymes injections attenuated cartilage degradation without exhibiting cytotoxicity toward the synovial membrane, lungs, and liver. Notably, based on proteome microarray data, PPBzymes specifically block the JNK phosphorylation, which modulates inflammatory OA pathogenesis. These findings indicate that PPBzymes might represent a biocompatible and effective nanotherapeutic for obstructing JNK phosphorylation.

A facile and sensitive magnetic relaxation sensing strategy based on the conversion of Fe3+ ions to Prussian blue precipitates for the detection of alkaline phosphatase and ascorbic acid oxidase

Herein, a novel magnetic relaxation sensing strategy based on the change in Fe³⁺ content has been proposed by utilizing the conversion of Fe³⁺ ions to Prussian blue (PB) precipitates. Compared with the common detection approach based on the valence state change of Fe³⁺ ions, our strategy can cause a larger change in the relaxation time of water protons and higher detection sensitivity since PB precipitate can induce a larger change in the Fe³⁺ ion concentration and has a weaker effect on the relaxation process of water protons relative to Fe²⁺ ions. Then, we employ alkaline phosphatase (ALP) as a model target to verify the feasibility and detection performance of the as-proposed strategy. Actually, ascorbic acid (AA) generated from the ALP-catalyzed L-ascorbyl-2-phosphate hydrolysis reaction can reduce potassium ferricyanide into potassium ferrocyanide, and potassium ferrocyanide reacts with Fe³⁺ to form PB precipitates, leading to a higher relaxation time. Under optimum conditions, the method for ALP detection has a wide linear range from 5 to 230 mU/mL, and the detection limit is 0.28 mU/mL, sufficiently demonstrating the feasibility and satisfactory analysis performance of this strategy, which opens up a new path for the construction of magnetic relaxation sensors. Furthermore, this strategy has also been successfully applied to ascorbic acid oxidase detection, suggesting its expansibility in magnetic relaxation detection.

Novel Siloxane Derivatives as Membrane Precursors for Lactate Oxidase Immobilization

We report new enzyme-containing siloxane membranes for biosensor elaboration. Lactate oxidase immobilization from water-organic mixtures with a high concentration of organic solvent (90%) leads to advanced lactate biosensors. The use of the new alkoxysilane monomers-(3-aminopropyl)trimethoxysilane (APTMS) and trimethoxy[3-(methylamino)propyl]silane (MAPS)-as the base for enzyme-containing membrane construction resulted in a biosensor with up to a two times higher sensitivity (0.5 A·M^-1·cm^-2) compared to the biosensor based on (3-aminopropyl)triethoxysilane (APTES) we reported previously. The validity of the elaborated lactate biosensor for blood serum analysis was shown using standard human serum samples. The developed lactate biosensors were validated through analysis of human blood serum.

Low-Spin Fe Redox-Based Prussian Blue with excellent selective dual-band electrochromic modulation and energy-saving applications

Dual-band electrochromic materials (DBEMs) are of utmost importance for smart windows to realize independent control of the visible (VIS) and near-infrared (NIR) light. However, very few single-component DBEMs are capable of independently and effectively controlling both VIS and NIR light. Here, we present Prussian blue (PB) with remarkable performance to replace the composite DBEMs that require deliberate design and complicated preparation. Excellent durability and capacity were achieved simultaneously due to the activated low-spin Fe in PB. A dual-band electrochromic device (DBED) by using PB thin films as electrochromic layers was constructed, exhibiting superior dual-band electrochromic performance, energy storage performance and memory effect. We show that the energy-saving DBED can be bleached without applying any external bias potential, and can be colored by using a commercial photovoltaic solar panel under ambient solar irradiation. The stored energy during coloration can be further used to light up the lights. Finally, the coloration mechanism of the DBED was studied by the density functional theory calculations, to shed light on the large optical transmittance modulation in both VIS and NIR regions. The new insights will advance the design of efficient and durable DBEMs and the development of bi-functional smart windows.

Highly Crystalline Prussian Blue for Kinetics Enhanced Potassium Storage

Prussian blue analogs (PBAs) are promising cathode materials for potassium-ion batteries (KIBs) owing to their large open framework structure. As the K⁺ migration rate and storage sites rely highly on the periodic lattice arrangement, it is rather important to guarantee the high crystallinity of PBAs. Herein, highly crystalline K₂ Fe[Fe(CN)₆ ] (KFeHCF-E) is synthesized by coprecipitation, adopting the ethylenediaminetetraacetic acid dipotassium salt as a chelating agent. As a result, an excellent rate capability and ultra-long lifespan (5000 cycles at 100 mA g^-1 with 61.3% capacity maintenance) are achieved when tested in KIBs. The highest K⁺ migration rate of 10^-9 cm² s^-1 in the bulk phase is determined by the galvanostatic intermittent titration technique. Remarkably, the robust lattice structure and reversible solid-phase K⁺ storage mechanism of KFeHCF-E are proved by in situ XRD. This work offers a simple crystallinity optimization method for developing high-performance PBAs cathode materials in advanced KIBs.

Flexible Inorganic All-Solid-State Electrochromic Devices toward Visual Energy Storage and Two-Dimensional Color Tunability

Multicolor display has gradually become a sought-after trend for electrochromic devices due to its broadened application scope. Meanwhile, the advantages of inorganic electrochromic devices such as stable electrochemical performance and good energy storage ability also have great attraction in practical production applications. However, there are still huge challenges for inorganic electrochromic materials to achieve multicolor transformation due to their single-color hue change. Herein, we design an inorganic and multicolor electrochromic energy storage device (MEESD) exhibiting flexibility and all-solid-state merits. Prussian blue (PB) and MnO₂, as the asymmetrical electrodes of this MEESD, show good pseudocapacitance property, matching charge capacity, and obvious color change. As a typical electrochromic device, the MEESD shows a fast response of 0.5 s and good coloration efficiency of 144.2 cm²/C. As an energy storage device, the MEESD presents excellent rate capability and volumetric energy/power density (84.2 mWh cm^-3/23.3 W cm^-3). Its energy level can be visually monitored by color contrast and optical modulation. In the charging/discharging process, its color can obviously change to various degrees of yellow, green, and blue along with 40% wide optical modulation at 710 nm. Meanwhile, the stability of the MEESD in a common and humidity environment was analyzed in detail from electrochemical, optical, and energy storage aspects. This work provides feasible thoughts to design multifunctional electrochromic devices integrated with inorganic, flexible, all-solid-state, multicolor, and energy storage properties.

Oral formulation of Prussian blue with improved efficacy for prophylactic use against thallium

OBJECTIVE

The present study is aimed to enhance the efficacy of Insoluble Prussian blue (PB) in the stomach. PB formulation was developed comprising of PB in combination with pH modifying agents particularly magnesium hydroxide, calcium carbonate, sodium carbonate, and sodium bicarbonate. pH profile and the binding efficacy of the final formulation was evaluated in simulated gastric fluid (SGF).

METHODS

The capsule formulation was optimized with desired in vitro characteristics. The final formulations (FF1-FF4) were evaluated for drug release, pH profile, and binding efficacy for thallium (Tl). The stability studies were performed in terms of drug assay, Fourier-transformed infrared (FTIR) spectroscopy and Thermo-gravimetric analysis (TGA). The in vivo study was performed in rats to determine the removal efficacy of optimized formulation (FF4) for Tl.

RESULTS

The PB formulation consisting of optimized PB granules and pH modifying agents showed a significant increase in the binding efficacy for Tl in SGF at an equilibrium time of 24 h. The Maximum Binding Capacity (MBC) of FF1-FF4 was found to be higher than commercially available Radiogardase^®-Cs capsules and PB granules alone in SGF. The blood Tl level in rats treated with FF4 showed three-fold decreases in the level of Tl in the blood (C_max) and Area under Curve (AUC) as compared to the control.

CONCLUSION

The results revealed that the developed oral PB formulation has a significantly higher efficiency of binding Tl at the acidic pH of the stomach thereby reducing its absorption into the systemic circulation. Thus, the optimized formulation of PB with pH-modifying agents is a better drug for prophylactic use in thallium ingestion.

Hybrid Au-star@Prussian blue for high-performance towards bimodal imaging and photothermal treatment

In recent years, branched or star-shaped Au nanostructures composed of core and protruding arms have attracted much attention due to their unique optical properties and morphology. As the clinically adapted nanoagent, prussian blue (PB) has recently gained widespread attention in cancer theranostics with potential applications in magnetic resonance (MR) imaging. In this article, we propose a hybrid star gold nanostructure（Au-star@PB）as a novel theranostic agent for T1-weighted magnetic resonance imaging (MRI)/ photoacoustic imaging（PAI） and photothermal therapy (PTT) of tumors. Importantly, the Au-star@PB nanoparticles function as effective MRI/PA contrast agents in vivo by increasing T1-weighted MR/PAI signal intensity and as effective PTT agents in vivo by decreasing the tumor volume in MCF-7 tumor bearing BALB / c mouse model as well as in vitro by lessening tumor cells growth rate. Interestingly, we found the main photothermal effect of Au-star@PB is derived from Au-star, but not PB. In summary, the hybrid structure of Au-star@PB NPs with good biological safety, significant photostability, dual imaging capability, and high therapeutic efficiency, might offer a novel avenue for the future diagnosis and treatment of cancer.

Recovery of Pure Methanol from Humid Gas Using Mn-Co Prussian Blue Analogue

Conventional methanol recovery and purification processes are highly energy-intensive; processes using selective adsorbents that consume low energy are preferable. However, conventional adsorbents have low methanol selectivity under humid conditions. In this study, we develop a selective methanol adsorbent, manganese hexacyanocobaltate (MnHCC), which enables the efficient removal of methanol from waste gas and its subsequent reuse. MnHCC adsorbs 4.8 mmol-methanol/g-adsorbent at 25 °C in a humid gas containing 5000 ppmv of methanol, which is five times higher than the adsorption capacity of activated carbon (0.86 mmol/g). Although MnHCC exhibits the simultaneous adsorption of methanol and water, it has a higher adsorption enthalpy for methanol. Thus, pure methanol (95%) was recovered via thermal desorption at 150 °C after dehydration. The estimated energy of this recovery was 18.9 MJ/kg-methanol, approximately half that of existing mass production methods. MnHCC is reusable and stable even after 10 cyclic experiments. Consequently, MnHCC has the potential to contribute to both the recycling of methanol from waste gas and its low-cost purification.

Tailoring abundant active-oxygen sites of Prussian blue analogues-derived adsorbents for highly efficient Yb(III) capture

The removal of rare earth elements in mineral processing wastewater is highly desirable but still challenging. In this study, three bimetallic Prussian blue analogues (PBA) and six corresponding oxides are prepared by co-precipitation and calcination methods, and then utilized to adsorb aqueous Yb(III) solution. The results of XRD, SEM, BET, and XPS indicate the successful synthesis of all the adsorbents. Among them, three PBA-oxide samples (PBO-800) exhibit the superior adsorption capacities (˃250 mg/g). The adsorption processes of Yb(III) are in accordance with the pseudo-second-order kinetic model and Langmuir model, simultaneously showing the spontaneous and endothermic thermodynamics. Moreover, PBO-800 can be reused after alkaline solution regeneration with less than 10% degradation after five consecutive adsorption-desorption cycles. More importantly, PBO-800 exhibits the impressive separation selectivity of Yb(III) and most light rare earth ions (e.g., 5.51 of Yb/La, 4.03 of Yb/Pr), as well as the selectivity of Yb(III) and alkali metal ions (e.g., 300.5 of Yb/Na, 256.2 of Yb/Ca). According to the characterization analysis and DFT calculation, the adsorption mechanism of Yb(III) by PBO-800 is mainly attributed to the strong interaction between the abundant active-oxygen sites and Yb(III), and the significant electrostatic attraction.

Removal of cesium and strontium for radioactive wastewater by Prussian blue nanorods

In this work, novel Prussian blue tetragonal nanorods were prepared by template-free solvothermal methods to remove radionuclide Cs and Sr. The as-prepared Prussian blue nanorods were identified and characterized by scanning electron microscopy, transmission electron microscope, Fourier transform infrared spectroscopic, thermogravimetric analysis, zeta potential, and surface analysis, and its sorption performance was tested by batch experiments. Our results suggest that Prussian blue nanorods exhibited better adsorption performance than co-precipitation PB or Prussian blue analogue composites. Thermodynamic analysis implied that the adsorption process was spontaneous and endothermic which was described well with the Langmuir isotherm and pseudo-second-order equation. The maximum adsorption capacity of PB nanorod was estimated to be 194.26 mg g^-1 and 256.62 mg g^-1 for Cs⁺ and Sr²⁺(adsorbate concentration at 500 mg L^-1, the temperature at 298 k, pH at 7.0). Moreover, the experimental results showed that the Prussian blue nanorods have high crystallinity, few crystal defects, and good stability under alkaline conditions. The adsorption mechanism of Cs⁺ and Sr²⁺ was studied by X-ray photoelectron spectroscopy, X-ray diffraction, and ⁵⁷Fe Mössbauer spectroscopy. The results revealed that Cs⁺ entered the PB crystal to generate a new phase, and most of Sr²⁺ was trapped in the internal crystal and the other exchanged Fe²⁺. Furthermore, the effect of co-existing ions and pH on PB adsorption process was also investigated. The results suggest that PB nanorods were an outstanding candidate for removing Cs⁺ and Sr²⁺ from radioactive wastewater.

PB@PDA nanocomposites as nanolabels and signal reporters for separate-type cathodic photoelectrochemical immunosensors in the detection of carcinoembryonic antigens

Photoelectrochemical (PEC) immunoassays exhibiting high sensitivity and decent operability have considerable potential in areas such as cancer diagnostics. In particular, cathodic PEC configurations can prevent interference from reductive substances, which can occur in biological samples; however, challenges remain in terms of sensitivity and operability. In this study, separate-type PEC immunoassays were developed for carcinoembryonic antigen (CEA) by combining microplate-based immune recognition and off-on cathodic PEC detection. Polydopamine (PDA)-coated Prussian blue (PB) nanoparticles (PB@PDA NPs) were used as signal tags to label the detection antibody. The PB NPs and PDA captured on the microplates both disassembled under strongly alkaline conditions to generate redox-active electron acceptors. The disassembled products were quantitatively transferred to PEC detection cells and synergistically enhanced the PEC current with microstructured BiOI, which operated as a cathodic semiconductor electrode. As proof of principle, carcinoembryonic antigen (CEA) was applied to elucidate the potential application of PEC immunoassay in clinical diagnosis, and the obtained linear range of the sensor was 0.001-100 ng mL^-1 with the detection limit of 54.9 fg mL^-1 (S/N = 3). The proposed separate-type off-on PEC strategy showed high sensitivity and decent operability for CEA detection, indicating its potential for the identification of other tumor markers.

Sensing soluble molecules through SERS substrates in one-step procedure: Unrevealing the Meiji woodblock printing materials

Ultrasensitive SERS substrates allowed us to detect complex mixtures of coloring components from Meiji Japanese woodblock prints (1868-1912). In museum settings, compositional analyses have limitations due to restrictions to sampling advised by conservators and curators for the adequate preservation of the objects. An additional layer of complexity is brought by the high heterogeneity of heritage materials, usually not resolved with commercial portable instruments. High-performance instruments for in situ analyses are seldom available in museums. Furthermore, the chambers of most instruments for morphological or chemical characterization accommodate small samples rather than large or medium-sized objects. The innovative sampling strategy herein proposed comprises the gentle touch-dry removal of small coloring molecules weakly bound to the surface of heritage objects, transferred through a silicone sampler to planar SERS substrates with selected solvents in a one-step procedure. The analytical protocol reduces the amount of sample necessary for reliable identification of color components down to nanograms. The selectivity of the solvents combined with the geometry of the planar SERS sensing devices produces reliable signals for molecular identification, with no need for incision or wetting of the printed material. Further, 3D Raman imaging allowed us to reach an unprecedented degree of molecular discrimination, advancing previously available minimally-invasive instrumental methods used in heritage science research. The validation with historical inks from Meiji woodblock prints led to the identification of soluble synthetic azo β-naphthols, barium sulfonic lakes, purple anilines, Prussian blue, glass arsenic sulfides and other traditional coloring media.

Iron-Vanadium Incorporated Ferrocyanides as Potential Cathode Materials for Application in Sodium-Ion Batteries

Sodium-ion batteries (SIBs) are potential replacements for lithium-ion batteries owing to their comparable energy density and the abundance of sodium. However, the low potential and low stability of their cathode materials have prevented their commercialization. Prussian blue analogs are ideal cathode materials for SIBs owing to the numerous diffusion channels in their 3D structure and their high potential vs. Na/Na⁺. In this study, we fabricated various Fe-V-incorporated hexacyanoferrates, which are Prussian blue analogs, via a one-step synthesis. These compounds changed their colors from blue to green to yellow with increasing amounts of incorporated V ions. The X-ray photoelectron spectroscopy spectrum revealed that V³⁺ was oxidized to V⁴⁺ in the cubic Prussian blue structure, which enhanced the electrochemical stability and increased the voltage platform. The vanadium ferrocyanide Prussian blue (VFPB1) electrode, which contains V⁴⁺ and Fe²⁺ in the Prussian blue structure, showed Na insertion/extraction potential of 3.26/3.65 V vs. Na/Na⁺. The cycling test revealed a stable capacity of ~70 mAh g^-1 at a rate of 50 mA g^-1 and a capacity retention of 82.5% after 100 cycles. We believe that this Fe-V-incorporated Prussian green cathode material is a promising candidate for stable and high-voltage cathodes for SIBs.

Prussian Blue Sensor for Bacteria Detection in Personal Protection Clothing

Biological hazards can be defined as substances that endanger the life of any living organism, most notably humans, and are often referred to as biohazards. Along with the use of personal protective equipment (PPE), early detection of contact is essential for the correct management and resolution of a biological threat, as well as lower mortality rates of those exposed. Herein, Prussian blue (PB) was evaluated as a functional compound applied on polyester knits to act as an on-site sensor for bacteria detection. In order to study the best compound concentration for the intended application, polymeric solutions of 0.5, 1 and 2 g/L were developed. The three conditions tested displayed high abrasion resistance (>2000 cycles). The bacterial sensing capacity of the coated knits was assessed in liquid and solid medium, with the functionalised substrates exhibiting the capability of detecting both Gram-positive and Gram-negative bacteria and changing colours from blue to white. Evaluation of water repellence and chemical penetration resistance and repellence was also performed in polyester functionalised with PB 0.5 and 1 g/L. Both knits showed a hydrophobic behaviour and a capacity to resist to penetration of chemicals and level 3 repellence effect for both acid and base chemicals.

Quantitative Evaluation of Cerebral Microhemorrhages in the Mouse Brain

Cerebral microhemorrhages are microscopic bleeds in the brain parenchyma and are the pathological substrates of cerebral microbleeds. Clinically and in mouse models, detection of cerebral microhemorrhages involves the use of magnetic resonance imaging and/or postmortem neuropathology techniques including hematoxylin and eosin (H & E) staining to detect extravasated red blood cells and fresh/acute microhemorrhages and Prussian blue staining to detect iron released from extravasated red blood cells and subacute/old microhemorrhages. Here we describe the step-by-step procedure for mouse brain processing and H & E and Prussian blue staining and quantification of acute (H & E-positive) and subacute (Prussian blue-positive) cerebral microhemorrhages in mouse brain tissues.

Synthesis of heated aluminum oxide particles impregnated with Prussian blue for cesium and natural organic matter adsorption: Experimental and machine learning modeling

Heated aluminum oxide particles impregnated with Prussian blue (HAOPs-PB) are synthesized for the first time using different molar ratios of aluminum sulfate and PB to improve the adsorption of cesium (¹³³Cs⁺) and natural organic matter (NOM) from an aqueous solution. The Cs⁺ adsorption from various aqueous solutions, including surface, tap and deionized water by synthesized HAOPs-PB, is investigated. The influencing factors such as HAOPs-PB mixing ratio, pH and dosage are studied. In addition, pseudo 1st and 2nd order is tested for adsorption kinetics study. A machine learning model is developed using gene expression programming (GEP) to evaluate and optimize the adsorption process for Cs⁺ and NOM removal. Synthesized adsorbent showed maximum adsorption at a 1:1 M ratio of aluminum sulfate and PB in DI, tap, and surface water. The pseudo 2nd order kinetics model described the Cs ⁺ adsorption by HAOPs-PB more accurately that indicating physiochemical adsorption. Adsorption of Cs⁺ showed an increasing trend with higher HAOPs-PB concentration, while high pH also favored the adsorption. Maximum NOM adsorption is found at a higher HAOPs-PB dosage and a neutral pH value. Furthermore, the proposed GEP model shows outstanding performance for Cs⁺ adsorption modeling, whereas a modified-GEP model presents promising results for NOM adsorption prediction for testing dataset by learning the relationship between inputs and output with R² values of 0.9348 and 0.889, respectively.

Cyanide within gold mine waste of the free state goldfields: A geochemical modelling approach

Cyanide, which remains the preferred chemical used in the gold extraction process, has the potential to be disposed of on goldmine tailings. South Africa has nine goldfields, producing approximately a third of the world's gold to date. The cyanide interacts with metals in the tailings environment, where Prussian blue [Formula: see text] and Turnbull's blue [Formula: see text] are among these. In previous studies, Prussian blue or Turnbull's blue have been found as a blue substance in tailings material. PHREEQC modelling software was used adding the mineralogical data from 16 tailings samples from the Free State goldfield. The results revealed that Prussian blue prefers to precipitate in an oxic environment and Turnbull's blue prefers an anoxic environment. It was also determined that their precipitation is affected by the availability of iron in solution. As soon as all of the iron is consumed in solution, all excess cyanide produces HCN, which is a free cyanide which volatilizes. Contrarily, Prussian and Turnbull's blue are CN_SAD compounds, only dissociating in extremely low pH condition in the absence of photolysis. Ultimately, these iron-cyanide compounds are able to immobilize cyanide, preventing seepage into environments such as the ground water. This along with an anoxic environment such as mine void, keeping the pH high, may be a possible solution for cyanide remediation.

NIR responsive nanoenzymes via photothermal ablation and hypoxia reversal to potentiate the STING-dependent innate antitumor immunity

Despite advances in combined photothermal/immunotherapy of tumor, the therapeutic effect has been impaired due to hypoxic microenvironment and inadequate immune activation. Manganese ions directly activated the stimulator of interferon genes (STING) pathway and induced innate antitumor immunity. Herein, a near infrared light (NIR)-responsive nanoenzyme (PB-Mn/OVA NE) was constructed by doping manganese into the ovalbumin (OVA)-templated Prussian blue (PB) nanoparticles. The resultant PB-Mn/OVA NEs exhibited favorable catalase activity to produce oxygen, which was conducive to alleviate the tumor hypoxic microenvironment. Under 808 ​nm NIR irradiation, the PB-Mn/OVA NEs with outstanding photothermal conversion efficiency of 30% significantly destroyed tumor cells by inducing immunogenic cell death (ICD). Impressively, the PB-Mn/OVA NEs could activate the cGAS-STING pathway to promote the maturation and the antigen cross-presentation ability of dendritic cells (DCs), which further activated cytotoxic T lymphocytes and memory T lymphocytes. Overall, this work presents a powerful nanoenzyme formula to integrate photothermal ablation and hypoxic reversal for triggering robust innate and adaptive antitumor immune response.

Tannic acid-assisted in-situ interfacial formation of Prussian blue-assembled adsorptive membranes for radioactive cesium removal

There is a growing interest in advanced materials that can effectively treat wastewater contaminated with radioactive cesium (¹³⁷Cs), which is an extremely hazardous material. Here, we report a new class of Cs-adsorptive membranes compactly assembled with Cs-adsorptive Prussian blue (PB) particles. The PB particle assembly was formed via an in-situ interfacial reaction between two PB precursors in the presence of tannic acid (TA) as a binder on a porous support. While the interfacial reaction enabled the formation of a defect-less PB network, TA enhanced the PB-PB and PB-support compatibilities, consequently producing a uniform, densely packed PB assembly near the support surface. The fabricated TA-assisted PB membrane (PB/TA-M) synergistically rejected Cs via a combination of adsorption and membrane filtration, although adsorption predominantly determined Cs rejection initially. Hence, the PB/TA-M membrane showed considerably higher Cs removal performance than commercial nanofiltration (NF) and reverse osmosis (RO) polyamide (PA) membranes for a sufficiently long operation time. Furthermore, the PB/TA-M membrane displayed excellent radioactive ¹³⁷Cs removal performance, significantly exceeding those of commercial NF and RO PA membranes due to its higher radiation stability, indicating its viability for application in treating actual radioactive wastewater.