Multivalent Elements Research Articles

A Dual-Targeting Biomimetic Nanoplatform Integrates SDT/CDT/Gas Therapy to Boost Synergistic Ferroptosis for Orthotopic Hepatocellular Carcinoma Therapy.

The development of efficient therapeutic strategies to promote ferroptotic cell death offers significant potential for hepatocellular carcinoma (HCC) treatment. Herein, this study presents an HCC-targeted nanoplatform that integrates bimetallic FeMoO4 nanoparticles with CO-releasing molecules, and further camouflaged with SP94 peptide-modified macrophage membrane for enhanced ferroptosis-driven multi-modal therapy of HCC. Leveraging the multi-enzyme activities of the multivalent metallic elements, the nanoplatform not only decomposes H2O2 to generate oxygen and alleviate tumor hypoxia but also depletes glutathione to inactivate glutathione peroxides 4, which amplify sonodynamic therapy and ferroptotic tumor death under ultrasound (US) irradiation. Meanwhile, the nanoplatform catalyzes the Fenton reaction to produce hydroxyl radicals for chemodynamic therapy. Elevated intracellular reactive oxygen species trigger the cascade release of CO, leading to lethal lipid peroxidation and further enhancing ferroptosis-mediated tumor therapy. This nanoplatform demonstrates robust anti-tumor efficacy under US irradiation with favorable biosafety in both subcutaneous and orthotopic HCC models, representing a promising therapeutic approach for HCC. Additionally, the findings offer new insights into tumor microenvironment modulation to optimize US-triggered multi-modal cancer therapy.

Augment of Ferroptosis with Photothermal Enhanced Fenton Reaction and Glutathione Inhibition for Tumor Synergistic Nano-Catalytic Therapy.

Ferroptosis-driven tumor ablation strategies based on nanotechnology could be achieved by elevating intracellular iron levels or inhibiting glutathione peroxidase 4 (GPX4) activity. However, the intracellular antioxidative defense mechanisms endow tumor cells with ferroptosis resistance capacity. The purpose of this study was to develop a synergistic therapeutic platform to enhance the efficacy of ferroptosis-based tumor therapy. In this study, a multifunctional nano-catalytic therapeutic platform (mFeB@PDA-FA) based on chemodynamic therapy (CDT) and photothermal therapy (PTT) was developed to effectively trigger ferroptosis in tumor. In our work, iron-based mesoporous Fe3O4 nanoparticles (mFe3O4 NPs) were employed for the encapsulation of L-buthionine sulfoximine (BSO), followed by the modification of folic acid-functionalized polydopamine (PDA) coating on the periphery. Then, the antitumor effect of mFeB@PDA-FA NPs was evaluated using Human OS cells (MNNG/HOS) and a subcutaneous xenograft model of osteosarcoma. mFe3O4 harboring multivalent elements (Fe2+/3+) could catalyze hydrogen peroxide (H2O2) into highly cytotoxic ˙OH, while the tumor microenvironment (TME)-responsive released BSO molecules inhibit the biosynthesis of GSH, thus achieving the deactivation of GPX4 and the enhancement of ferroptosis. Moreover, thanks to the remarkable photothermal conversion performance of mFe3O4 and PDA shell, PTT further synergistically enhanced the efficacy of CDT and facilitated ferroptosis. Both in vivo and in vitro experiments confirmed that this synergistic therapy could achieve excellent tumor inhibition effects. The nanotherapeutic platform mFeB@PDA-FA could effectively disrupted the redox homeostasis in tumor cells for boosting ferroptosis through the combination of CDT, PTT and GSH elimination, which provided a new perspective for the treatment of ferroptosis sensitive tumors.

Experimental determination of tin partitioning between titanite, ilmenite, and granitic melts using improved capsule designs

Abstract Investigating mineral/melt Sn partitioning at high temperatures and pressures is a difficult task because Sn is a redox-sensitive multivalent element and easily alloys with noble metal sample capsules. To obtain accurate Sn partition coefficients between titanite, ilmenite, and granitic melts, we developed single capsule Pt or Au and double capsule Pt95Rh5 (or Au)-Re designs to avoid significant Sn loss at a controlled oxygen fugacity (fO2). With these new capsule designs, we performed piston-cylinder experiments of Sn partitioning between titanite, ilmenite, and granitic melts. The experimental P-T-fO2 conditions were 0.5–1.0 GPa, 850–1000 °C, and ~QFM+8 to ~QFM-4 (quartz-fayalite-magnetite, QFM, buffer), with fO2 controlled by the solid buffers of Ru-RuO2, Re-ReO2, Co-CoO, graphite, and Fe-FeO. The obtained mineral/melt Sn partition coefficients (DSnmin/melt) are 0.48–184.75 for titanite and 0.03–69.45 for ilmenite at the experimental conditions. The DSnmin/melt values are largely dependent on fO2, although the effects of temperature and melt composition are also observed. DSnTtn/melt strongly decreases with decreasing fO2, from ~46–185 at the most oxidizing conditions (Ru-RuO2 buffer), to ~2–16 at moderately oxidizing to moderately reducing conditions (Re-ReO2 to Co-CoO and graphite buffers), to <1 at the most reducing conditions (Fe-FeO buffer). DSnIlm/melt exhibits a variation trend similar to DSnTtn/melt but is always lower than DSnTtn/melt at a given fO2. These DSnmin/melt values can be applied to quantitatively assess the mineralization potential of granitic magmas. Using DSnTtn/melt, we estimate that Sn contents are ~150–400 ppm in the pre-mineralization magmas of the tin-mineralized Qitianling plutons (South China).

SrCoO3-based perovskites with enhanced electrochemical performance through structural tailoring induced by B-site substitution

The progression of supercapacitor technology hinges on the discovery of high-performance electrode materials to enhance energy storage. SrCoO3-δ perovskite holds considerable promise potential as an anion intercalation electrode material. To elucidate the structural and electrochemical performance modulation rules of SrCoO3-based perovskites, this study synthesized SrCo0.875M0.125O3-δ (M = Ti, Ta, Nb, Fe) perovskites with different B-site ion substitutions. The structural tailoring induced by B-site substitution were thoroughly investigated alongside their corresponding electrochemical performance. Notably, SrCo0.875Ti0.125O3-δ exhibited a simple cubic structure, while the other samples displayed a tetragonal structure. Additionally, SrCo0.875Fe0.125O3-δ displayed numerous oxygen vacancies and significant distortion in the [CoO6] octahedron, which is attributed to the lower valence state of Fe. At a current density of 1 A g−1, the specific capacities of SrCo0.875M0.125O3-δ (M = Nb, Ti, Fe, Ta) perovskites were 984.43, 853.33, 503.53, and 452.00C/g, respectively. SrCo0.875Nb0.125O3-δ demonstrated the highest specific capacity and capacity retention rate across various current density, owing to its relatively stable structure with appropriate oxygen vacancies and multivalent state changes of Nb. In contrast, SrCo0.875Fe0.125O3-δ, with excessive oxygen vacancies and severe structural distortions, exhibited restricted electrochemical performance, particularly at higher current densities. Integrating structural and performance analysis, this work proposes an optimization strategy for the electrochemical performance of SrCoO3-δ-based perovskite electrode materials, emphasizing the importance of tailoring multivalent B-site elements to achieve a stable perovskite structure with appropriate oxygen vacancies.

Tumor-targeted delivery of hyaluronic acid/polydopamine-coated Fe2+-doped nano-scaled metal–organic frameworks with doxorubicin payload for glutathione depletion-amplified chemodynamic-chemo cancer therapy

Chemodynamic therapy (CDT), an emerging cancer treatment modality, uses multivalent metal elements to convert endogenous hydrogen peroxide (H2O2) to toxic hydroxyl radicals (•OH) via a Fenton or Fenton-like reaction, thus eliciting oxidative damage of cancer cells. However, the antitumor potency of CDT is largely limited by the high glutathione (GSH) concentration and low catalytic efficiency in the tumor sites. The combination of CDT with chemotherapy provides a promising strategy to overcome these limitations. In this work, to enhance antitumor potency by tumor-targeted and GSH depletion-amplified chemodynamic-chemo therapy, the hyaluronic acid (HA)/polydopamine (PDA)-decorated Fe2+-doped ZIF-8 nano-scaled metal–organic frameworks (FZ NMs) were fabricated and utilized to load doxorubicin (DOX), a chemotherapy drug, via hydrophobic, π-π stacking and charge interactions. The attained HA/PDA-covered DOX-carrying FZ NMs (HPDFZ NMs) promoted DOX and Fe2+ release in weakly acidic and GSH-rich milieu and exhibited acidity-activated •OH generation. Through efficient CD44-mediated endocytosis, the HPDFZ NMs internalized by CT26 cells not only prominently enhanced •OH accumulation by consuming GSH via PDA-mediated Michael addition combined with Fe2+/Fe3+ redox couple to cause mitochondria damage and lipid peroxidation, but also achieved intracellular DOX release, thus eliciting apoptosis and ferroptosis. Importantly, the HPDFZ NMs potently inhibited CT26 tumor growth in vivo at a low DOX dose and had good biosafety, thereby showing promising potential in tumor-specific treatment.

Gold Nanodots-Anchored Cobalt Ferrite Nanoflowers as Versatile Tumor Microenvironment Modulators for Reinforced Redox Dyshomeostasis.

Given that tumor microenvironment (TME) exerts adverse impact on the therapeutic response and clinical outcome, robust TME modulators may significantly improve the curative effect and increase survival benefits of cancer patients. Here, Au nanodots-anchored CoFe2O4 nanoflowers with PEGylation (CFAP) are developed to respond to TME cues, aiming to exacerbate redox dyshomeostasis for efficacious antineoplastic therapy under ultrasound (US) irradiation. After uptake by tumor cells, CFAP with glucose oxidase (GOx)-like activity can facilitate glucose depletion and promote the production of H2O2. Multivalent elements of Co(II)/Co(III) and Fe(II)/Fe(III) in CFAP display strong Fenton-like activity for·OH production from H2O2. On the other hand, energy band structure CFAP is superior for US-actuated 1O2 generation, relying on the enhanced separation and retarded recombination of e-/h+ pairs. In addition, catalase-mimic CFAP can react with cytosolic H2O2 to generate molecular oxygen, which may increase the product yields from O2-consuming reactions, such as glucose oxidation and sonosensitization processes. Besides the massive production of reactive oxygen species, CFAP is also capable of exhausting glutathione to devastate intracellular redox balance. Severe immunogenic cell death and effective inhibition of solid tumor by CFAP demonstrates the clinical potency of such heterogeneous structure and may inspire more relevant designs for disease therapy.

Material modification of electrodes in microbial electrochemical system to enhance electrons utilization on the electrode and its impact on microorganisms

Previous research has established a MES embedding a microbial electrode to facilitate the degradation of antibiotics in water. We modified microbial electrodes in the MES with PEDOT and rGO to enhance electron utilization on electrodes and to further promote antibiotic degradation. Density functional theory calculations on the SMX molecule indicated that the C4-S8 and S8-N27 bonds are the most susceptible to electron attack. The introduction of various functional groups and multivalent elements enhanced the electrodes' capacitance and electron mediation capabilities. This led to enhance both electron utilization on the electrodes and the removal efficiency of SMX. After 120 h, the degradation efficiency of SMX by PEDOT and rGO-modified electrodes increased by 45.47 % and 25.19 %, respectively, compared to unmodified electrodes. The relative abundance of sulfate-reducing and denitrifying bacteria significantly increased in PEDOT and rGO-modified electrodes, while the abundance of nitrifying bacteria and potential antibiotic resistance gene host microbes significantly decreased. The impact of PEDOT modification positively influenced microbial Cellular Processes, including cell growth, death, and motility. This study provides insights into the mechanisms of direct electron involvement in antibiotic degradation steps in microbial electrochemistry, and provides a possible path for improved strategies in antibiotic degradation and sustainable environmental remediation.

N/S co-doped Nb2CTx MXene as the effective catalyst for improving the hydrogen storage performance of MgH2

While MgH2 has high hydrogen storage capacity, its high dehydrogenation temperature and sluggish de-/hydrogenation rate have hindered practical application. In the present work, a non-metallic element (N, S) co-doped Nb2CTx MXene catalyst (N/S-Nb2CTx) is employed to improve the hydrogen storage property of MgH2. The dehydrogenation activation energy of MgH2+N/S-Nb2CTx composite is reduced to 70.00 kJ mol–1 H2, which is much lower than that of MgH2+Nb2CTx (99.44 kJ mol–1 H2) and Milled-MgH2 (133.19 kJ mol–1 H2). The composite can release about 4.78 wt% of H2 within 30 min at 225 °C and uptake about 4.00 wt% of H2 within 80 min even at 30 °C under 30 bar H2, which is significantly better than most of the reported MgH2+Nb-based-catalyst composites. The mechanism analysis reveals that the stable layered structure of the N/S-Nb2CTx catalyst provides enough nucleation sites for MgH2/Mg, and the in-situ formed substances (Nb, NbO2) play the role of elongating Mg–H bond. Besides, the N, S co-doped effectively enhances the ability of multivalent Nb elements to promote the electron transfer between Mg2+ and H–, and it promotes the diffusion of hydrogen through weakening the interaction between Nb and H atoms, thus the de-/hydrogenation kinetics and cyclic stability of MgH2 is significantly improved. This work not only proves that Nb2CTx can effectively enhance its catalytic activity by N and S co-doping, but also provides a MXene-based catalyst design concept for highly efficient hydrogen storage catalysts.

Modelling Ca2+ Mobility and Dynamics in Solvent-Free Molten Salt Electrolytes for Calcium Batteries

Multivalent elements based batteries using earth-abundant minerals is a route with promises, not only from a performance but also from a supply and cost point of view; this is not the last true for calcium (Ca) batteries since Ca is the fifth most abundant element in the Earth's crust [1,2,3]. There is, however, no functional electrolyte available yet for Ca batteries, calling for early modelling to be made to map the influence of different Ca-salts and salt concentrations on electrolyte physicochemical properties such as density, viscosity, ionic conductivity, charge carrier dynamics and diffusivity [3, 4]. One particular route little trodden is molten salt electrolytes (MSEs), materials that consist of ions with different valences in direct contact with each other due to the complete absence of any solvent. In practice, MSEs are multicomponent salt mixtures with reduced melting points with respect to the ingoing components and furthermore they also expand the operating temperature range upwards as compared to conventional liquid electrolytes. Moreover, MSEs have high ionic conductivities due to their intrinsically high ionic content and ionic mobility. Additionally, MSEs exhibit wide electrochemical stability windows, non-flammability, and non-toxicity [5, 6]. We have investigated MSEs composed of Ca(FSI)2, LiFSI, NaFSI, and KFSI, by molecular dynamics (MD) simulations. Apart from the basic properties, we focus on the relative dynamical properties of the different cations in the MSEs in order to obtain a fundamental understanding of the systems’ behaviour, both globally and locally, but for natural reasons with special emphasis on the Ca2+ ions.

Multiphase synergistic immobilization of complex trialkyl phosphine oxide end-waste into an iron-containing aluminosilicate glass-ceramic

The objective of this study was to address the challenges associated with complex TRPO waste, by utilizing a natural aluminosilicate material to produce glass-ceramic waste forms. When the simulated waste content was below 30 wt.%, glassy waste forms were successfully obtained. Ce and Fe played crucial roles in the formation of Si–O–Ce bonds and [FeO4]-tetrahedra in the glass network, which effectively immobilized other waste elements. However, when the waste content exceeded 30 wt.%, the waste was incorporated into feldspar, iron-manganese crystals, fluorite ceramic, and glass. This combination of ceramic and glass matrices synergistically immobilized the waste, resulting in excellent mechanical performance and chemical durability. The leaching rates of LRCe and LRNd were remarkably low around ∼10−6 to 10−7 g m−2 d−1, after 42 d. Furthermore, the study also investigated the role of multi-valence elements, such as Ce, Fe, and Mn, in the formation of iron-containing aluminosilicate glass-ceramics. The findings offer a novel approach to effectively immobilize complex nuclear waste.

Interpretation of experimental findings on the structure of glass in the CaO–MoO3–P2O5 system using a thermodynamic model including oxidation–reduction equilibria

This work extends the thermodynamic model of associated solutions used in the past to describe the structure and properties of glasses to the area of complex multicomponent glasses with polyvalent elements, where it has not been applied until now either due to the absence of Gibbs energies of formation of the necessary compounds or due to oxidation–reduction equilibrium in the presence of a gas phase containing oxygen. While the fitting of unknown Gibbs energies based on experimental data has already been applied to some extent in our previous work, the implementation of redox is, to the best of our knowledge, new. Four concentration series were taken from the published data from the glass-forming ternary system CaO–MoO3−P2O5: A) xMoO3−(0.5–0.75x)CaO−(0.5–0.25x)P2O5; B) xMoO3−(0.5–0.875x)CaO−(0.5–0.125x)P2O5; C) xMoO3−(0.5−x)CaO−0.5P2O5; M) xMoO3−(1−x)P2O, for which the distributions of Qn units were also published (Q denotes the PO4 tetrahedral unit with n bridging oxygens) by the 31P MAS NMR method and the Mo[V]/ΣMo fraction by the ESR method [Černošek et al. (J Solid State Chem 303:122522, 2021); Holubová et al., (J Non-Cryst Solids 607:122222, 2023)]. The following compounds were considered in the TD model: P2O5, CaO, Mo[VI]O3, Ca(PO3)2, Ca2P2O7, (Mo[VI]O2)(PO3)2, (Mo[VI]O2)2(P2O7), (Mo[VI]O2)3(PO4)2, (Mo[V]O)2(PO3)2(P2O7), (Mo[V]O)PO4. All except the hypothetical compound (Mo[VI]O2)3(PO4)2 exist, and their structure is known. Binary phosphate compounds with molybdenum lack Gibbs energies of formation. Therefore, one of the series, namely A, was used to determine these energies by nonlinear regression with the help of a genetic algorithm, without/with redox, and then the distribution of Qn units and the fraction of Mo[V]/ΣMo was predicted for the remaining series. It was found that the distribution of Qn units can be described by the TD model with redox only. During the reduction of molybdenum, the distribution of Qn unit’s changes, and thus also the connectivity of the phosphate network, for example, according to the reactions: (MoO2)2(P2O7)—> 2(MoO)PO4 + 1/2O2, in which Q1—> Q0 and 2(MoO2)(PO3)2—> (MoO)2(PO3)2(P2O7) + 1/2O2 in which Q2—> Q1. Despite the fact that the TD model with redox gives excellent agreement in the case of the Qn distribution, the agreement with the ESR measurements of the Mo[V]/ΣMo ratio is not good. The TD model predicts significantly more pentavalent molybdenum in the glass.

A mineralogical reason why all exoplanets cannot be equally oxidizing

ABSTRACT From core to atmosphere, the oxidation states of elements in a planet shape its character. Oxygen fugacity ($f_{\rm O_2}$) is one parameter indicating these likely oxidation states. The ongoing search for atmospheres on rocky exoplanets benefits from understanding the plausible variety of their compositions, which depends strongly on their oxidation states – and if derived from interior outgassing, on the $f_{\rm O_2}$ at the top of their silicate mantles. This $f_{\rm O_2}$ must vary across compositionally diverse exoplanets, but for a given planet, its value is unconstrained insofar as it depends on how iron (the dominant multivalent element) is partitioned between its 2+ and 3+ oxidation states. Here, we focus on another factor influencing how oxidizing a mantle is – a factor modulating $f_{\rm O_2}$ even at fixed Fe3+/Fe2+ – the planet’s mineralogy. Only certain minerals (e.g. pyroxenes) incorporate Fe3+. Having such minerals in smaller mantle proportions concentrates Fe3+, increasing $f_{\rm O_2}$. Mineral proportions change within planets according to pressure, and between planets according to bulk composition. Constrained by observed host star refractory abundances, we calculate a minimum $f_{\rm O_2}$ variability across exoplanet mantles, of at least two orders of magnitude, due to mineralogy alone. This variability is enough to alter by a hundredfold the mixing ratio of SO2 directly outgassed from these mantles. We further predict that planets orbiting high-Mg/Si stars are more likely to outgas detectable amounts of SO2 and H2O; and for low-Mg/Si stars, detectable CH4, all else equal. Even absent predictions of Fe3+ budgets, general insights can be obtained into how oxidizing an exoplanet’s mantle is.

Structural, electrical and electrochemical properties of Na2NixMn2−xFe(PO4)3as positive electrode material for sodium-ion batteries

The design of synthetic Alluaudite cathode materials has attracted much interest. However, their poor electrochemical activity and the limited kinetics have prevented them from practical applications, both stationary and mobile. Therefore, we provide in this work, a comprehensive study on the effect of combining 3d multivalent elements (Ni2+, Mn2+, Fe2+) and small particle sizes on structural, electrical and electrochemical properties of a series of Na2NixMn2−xFe(PO4)3 Alluaudite phases using a plethora of techniques. We systematically investigated the impact of the crystal structure, morphology and the density of the samples on Na-ion transport and the associated activation energies. Electrochemical performances of the prepared phases were investigated as positive electrode on a Na-ion battery by means of galvanostatic charge/discharge technique. An enhanced electrochemical performance was obtained by improving the composition of the slurry and the optimization of the electrolyte formulation, thus, affecting the electrochemical performances and cycling stability.

Light stable Cr isotope compositions of mid-ocean ridge basalts: Implications for mantle source composition

Stable isotopes of chromium (Cr) and iron (Fe), both multivalent elements in silicate melts, are valuable proxies of redox conditions in magmatic systems. Partial melting and fractional crystallization have been identified as the dominant fractionation processes for Cr and Fe isotopes in high-temperature reservoirs that can lead to small but detectable isotope variations in igneous rocks. More recently, however, the source mineralogy has been suggested to play an important role, which can ultimately affect the magnitude of Cr and Fe isotopic fractionation during partial melting and thus the Cr and Fe isotopic composition of the originating melt.With the aim to investigate the role of magmatic processes and the source Cr and Fe isotope signatures on the isotope composition of these transition metals in normal mid-ocean ridge basalts (N-MORB), we analyzed 21 well-characterized MORB glasses from the southern East-Pacific Rise, Pacific-Antarctic Ridge and Mid-Atlantic Ridge. The Cr isotope compositions of N-MORB show a narrow range from −0.278 to −0.186 ‰ in δ53/52Cr (i.e., difference of a sample’s 53Cr/52Cr ratio relative to the international reference material NIST SRM979), with an average value of −0.237 ± 0.050 ‰ (2SD; n = 19). As such, the average N-MORB δ53/52Cr value is significantly lower than that of Bulk Silicate Earth of −0.12 ± 0.06 ‰ and the Cr isotope compositions reported for most ocean island basalts ranging from ∼ −0.23 to 0.00 ‰. Iron isotopic compositions of these MORB range from +0.032 to +0.137 ‰ in δ56/54Fe (i.e., difference of a sample’s 56Fe/54Fe ratio relative to the international reference material IRMM014) and are within the range of previously published MORB data. The lack of correlations between N-MORB Cr isotope signatures and indices of magmatic differentiation suggests a negligible control of this process on Cr stable isotopes. Partial melting modeling using pMELTS provides evidence that the significant offset towards lower δ53/52Cr values of N-MORB cannot be produced by decompression partial melting of a lherzolithic source such as the depleted upper mantle alone. Instead, we suggest that the lower δ53/52Cr values of MORB could be linked to intrinsic small-scale 53Cr-depleted pyroxene-rich domains in the upper mantle that influence the melt’s Cr isotopic budget during partial melting.

La0.8Sr0.2Mn0.8Co0.2O3-δ perovskite as an efficient functional electrocatalyst for oxygen reduction reactions

The negative effects of the widespread and rough use of fossil energy have promoted the emergence of new energy technologies. Cost-effective electrocatalysts play an irreplaceable role in energy conversion and storage, especially oxygen reduction reactions (ORR) catalysts. While the reserves of precious metal catalysts are rare and expensive, it is of prime importance to develop catalysts that can replace precious metals. In the present work, La0.8Sr0.2Mn0.8Co0.2O3-δ (LSMC) with Mn and Co is successfully prepared by sol-gel method and subsequent calcination. The characterizations of physical phase, microstructure, BET and valence state of elements demonstrate that LSMC material possesses ample mesoporous structure, large specific surface area, and multivalent elements, which can provide abundant active sites for ORR. The electrochemical tests reveal that the LSMC delivers outstandingly higher electrocatalytic activity for ORR, relatively lower overpotential and Tafel slope and a better long-term stability than the other perovskites (LSM, LSC) under alkaline condition. Furthermore, the coupling effects of high content of high-valence Co, multivalent Mn and large amounts of adsorbed oxygen endow the catalyst excellent ORR electrocatalytic activity. The present work investigating the effect of Mn and Co elements on the electrocatalysis of LSMC perovskite, will provide the possibility of developing a new type of perovskite electrocatalyst with excellent ORR electrocatalytic activity and low cost.

Redox‐Independent Low Water Solubility in Quartz and Implications for Water Storage in the Crust

AbstractQuartz is an important mineral constituent of the continental crust, which commonly contains trace amounts of water as hydroxyl in the lattice. Despite considerable efforts to document the roles of pressure, temperature, and chemistry on water storage in quartz, the effect of redox state, a key thermodynamic factor in Earth sciences, has not been well established. We assessed the redox effect on water solubility in quartz at 2 and 10 kbar and 800°C, by equilibrating two natural gem‐quality crystals with water over a range of redox conditions. Recovered samples show infrared absorption bands at 3,100–3,600 cm−1. Dehydration experiments at 1200°C (room pressure) suggest that the two bands at ∼3,197 and 3,293 cm−1 are linked to Si‐O overtones, with the other bands to hydroxyl. The water solubility, ∼3.7–32.2 ppm wt. H2O, is redox‐independent, differing from other minerals such as feldspar, pyroxenes, garnet, rutile, and olivine in which the water solubility is significantly redox‐dependent. This provides evidence that the water incorporation in quartz is not controlled by polyvalent elements and/or other redox‐linked mechanisms. Considering the roles of Al, Li, and B in incorporating water and its low solubility over remarkable variations in the abundances of those elements in most natural samples, quartz is not a major water carrier compared to other nominally anhydrous minerals (NAMs) in the crust. The partitioning of water between quartz and other crustal NAMs such as feldspar, pyroxenes, rutile, and garnet is redox‐influenced, and is unlikely to be constant in the crust.

Shell-core COF@Co3O4 Z-scheme heterojunctions for triple amplification of oxidative stress to enhance nanocatalytic-sonodynamic tumor therapy

Constructing efficient nanozyme platforms with multiple amplification of tumor oxidative stress is crucial to enhance the reactive oxygen species (ROS)-mediated tumor therapy. However, the inherent low catalytic activity and unsustainability of nanozymes in the highly complex tumor microenvironment (TME) severely restricted their clinical applications. Herein, we first reported a heterojunction (HJ)-enhanced nanocatalytic-sonodynamic therapy nanoplatform based on COF@Co3O4 Z-scheme HJs with shell-core architecture by coating COF on the surface of Co3O4 nanospheres. The as-prepared Co3O4 nanospheres not only exhibited excellent sonodynamic properties owing to the narrow bandgap (1.37 eV), but also possessed peroxidase-like, catalase-like, and glutathione peroxidase-like catalytic activities to realize the amplification of ROS levels and relieve tumor hypoxia due to the presence of multivalent Co element. More importantly, the ultrasound (US)-triggered ROS generation ability and triple enzyme-mimic activity of Co3O4 nanospheres were greatly enhanced by the encapsulation of COF to fabricate Z-scheme HJs with large interfacial contact area. Based on the improved spatial separation dynamics of US-generated electron-hole pairs and accelerate carrier transfer process, complete tumor eradication without recurrence was realized by the synergetic therapeutic effect of COF@Co3O4 through HJ-enhanced nanocatalytic-sonodynamic therapy. This work presents highly efficient nanozyme platforms with both multiple enzyme-mimic catalytic activity and sonodynamic properties, which will open up a promising approach to engineer semiconductor Z-scheme HJs for enhanced tumor therapy.

Chromium toxicity, speciation, and remediation strategies in soil-plant interface: A critical review.

In recent decades, environmental pollution with chromium (Cr) has gained significant attention. Although chromium (Cr) can exist in a variety of different oxidation states and is a polyvalent element, only trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)] are found frequently in the natural environment. In the current review, we summarize the biogeochemical procedures that regulate Cr(VI) mobilization, accumulation, bioavailability, toxicity in soils, and probable risks to ecosystem are also highlighted. Plants growing in Cr(VI)-contaminated soils show reduced growth and development with lower agricultural production and quality. Furthermore, Cr(VI) exposure causes oxidative stress due to the production of free radicals which modifies plant morpho-physiological and biochemical processes at tissue and cellular levels. However, plants may develop extensive cellular and physiological defensive mechanisms in response to Cr(VI) toxicity to ensure their survival. To cope with Cr(VI) toxicity, plants either avoid absorbing Cr(VI) from the soil or turn on the detoxifying mechanism, which involves producing antioxidants (both enzymatic and non-enzymatic) for scavenging of reactive oxygen species (ROS). Moreover, this review also highlights recent knowledge of remediation approaches i.e., bioremediation/phytoremediation, or remediation by using microbes exogenous use of organic amendments (biochar, manure, and compost), and nano-remediation supplements, which significantly remediate Cr(VI)-contaminated soil/water and lessen possible health and environmental challenges. Future research needs and knowledge gaps are also covered. The review's observations should aid in the development of creative and useful methods for limiting Cr(VI) bioavailability, toxicity and sustainably managing Cr(VI)-polluted soils/water, by clear understanding of mechanistic basis of Cr(VI) toxicity, signaling pathways, and tolerance mechanisms; hence reducing its hazards to the environment.

Joint-detection of Salmonella typhimurium and Escherichia coli O157:H7 by an immersible amplification dip-stick immunoassay

To explore the superiority of multifunctional nanocomposites and realize the joint-detection of foodborne pathogens, an immersible amplification dip-stick immunoassay (DSIA) was exploited for the sensitive detection of Salmonella typhimurium (S. typhi) and Escherichia coli O157:H7 (E. coli O157:H7). Saving for the basic colorimetric performance, the reporter molecule of CoFe2O4 (CFO) possesses multivalent elements (Co2+/3+, Fe2+/3+) as well as multifunction of superior catalase-like activity and magnetic properties. By dint of the catalytic activity of CFO, a directly immersible amplification can be simply achieved to endure the DSIA with an intensive signal and a dual-visible mode for the determination of S. typhi and E. coli O157:H7. In virtue of the magnetic separation and enrichment capability of the CFO, the DSIA can perform a matrix-interference-free detection and obtain a dynamic detection range of 102–108 CFU/mL and a low assay limit of 102 CFU/mL. Moreover, the DSIA has reasonable recovery rates for contamination monitoring of two target bacteria in milk and beef samples. Our research provides a persuasive supplement for the application of multifunctional nanocomposites in the ongoing dip-stick immunoassay and an alternative strategy for the efficient detection of foodborne pathogens.

Amplification of oxidative stress with a hyperthermia-enhanced chemodynamic process and MTH1 inhibition for sequential tumor nanocatalytic therapy.

During chemodynamic therapy (CDT), tumor cells can adapt to hydroxyl radical (˙OH) invasion by activating DNA damage repairing mechanisms such as initiating mutt homologue 1 (MTH1) to mitigate oxidation-induced DNA lesions. Therefore, a novel sequential nano-catalytic platform MCTP-FA was developed in which ultrasmall cerium oxide nanoparticle (CeO2 NP) decorated dendritic mesoporous silica NPs (DMSN NPs) were used as the core, and after encapsulation of MTH1 inhibitor TH588, folic acid-functionalized polydopamine (PDA) was coated on the periphery. Once endocytosed into the tumor, CeO2 with multivalent elements (Ce3+/4+) could transform H2O2 into highly toxic ˙OH through a Fenton-like reaction to attack DNA as well as eliminating GSH through a redox reaction to amplify oxidative damage. Meanwhile, controllable release of TH588 hindered the MTH1-mediated damage repair process, further aggravating the oxidative damage of DNA. Thanks to the excellent photothermal performance of the PDA shell in the near-infrared (NIR) region, photothermal therapy (PTT) further improved the catalytic activity of Ce3+/4+. The therapeutic strategy of combining PTT, CDT, GSH-consumption and TH588-mediated amplification of DNA damage endows MCTP-FA with powerful tumor inhibition efficacy both in vitro and in vivo.