Weak Acidic Conditions Research Articles

Hyaluronic acid-mediated targeted nano-modulators for activation of pyroptosis for cancer therapy through multichannel regulation of Ca2+ overload.

Calcium-based nanomaterials-mediated Ca2+ overload-induced pyroptosis and its application in tumor therapy have received considerable attention. However, the calcium buffering capacity of tumor cells can maintain mitochondrial calcium homeostasis, so it is important to effectively disrupt this homeostasis to activate pyroptosis. Here, a nano-modulator CUR@CaCO3-PArg@HA (CCAH) was developed to regulate calcium overload in multiple channels and activate pyroptosis. Hyaluronic acid (HA)-coated nano-modulators achieve tumor targeting, and under the weakly acidic conditions of the tumor microenvironment (TME), CaCO3 nanoparticles rapidly release curcumin (CUR), inhibit the outflow of intracellular Ca2+, and release exogenous Ca2+. Meanwhile, poly-L-arginine (PArg) reacts with reactive oxygen species (ROS) generated by mitochondrial imbalance, releasing nitric oxide (NO) and stimulating the endoplasmic reticulum to release endogenous Ca2+. The combined action of endogenous and exogenous Ca2+ effectively activates caspase-1, which cleaves gasdermin-D (GSDMD) to produce the active N-terminus (GSDMD-N), effectively activating pyroptosis. Notably, the generated ROS and NO can also generate more oxidizing ONOO-, further exacerbating the imbalance in mitochondrial homeostasis. This work demonstrates that simultaneous modulation of exogenous and endogenous Ca2+ can disrupt mitochondrial Ca2+ homeostasis and effectively activate pyroptosis to treat tumors, which is expected to promote the progression of cancer treatment in the future.

Electrochemical Reduction of CO2 to CH3OH Catalyzed by an Iron Porphyrinoid.

Designing catalysts for the selective reduction of CO2, resulting in products having commercial value, is an important area of contemporary research. Several molecular catalysts have been reported to facilitate the reduction of CO2 (both electrochemical and photochemical) to yield 2e-/2H+ electron-reduced products, CO and HCOOH, and selective reduction of CO2 beyond 2e-/2H+ is rare. This is partly because the factors that control the selectivity of CO2 reduction beyond 2e- are not yet understood. An iron chlorin complex with a pendent amine functionality in its second sphere, known to selectively catalyze CO2RR to HCOOH with a very low overpotential from its formal Fe(I) state, can catalyze CO2RR from its formal Fe(0) state by 6e-/6H+, forming CH3OH as a major product with a Faradaic yield of ∼50%. Mechanistic investigations using in situ spectro-electrochemistry indicate that the reactivity of a low-spin d7 FeI-COOH intermediate species generated during CO2RR is crucial in determining the product selectivity of this reaction. In weakly acidic conditions, C-protonation of this FeI-COOH species, which is also chemically prepared and spectroscopically characterized, leads to HCOOH. The O-protonation, leading to C-OH bond cleavage and eventually to CH3OH, is ∼3 kcal/mol higher in energy and can be achieved in more acidic solutions. Hydrogen bonding to the pendent amine in the catalyst stabilizes reactive intermediates formed in the CO2RR and enables 6e-/6H+ reduction of CO2 to CH3OH.

Importance of the Cation-Water Interaction on Water Dissociation for Hydrogen Evolution

The solid-liquid interface models are generally concentrated on understanding either covalent interactions between adsorbates and solid surfaces or long-range liquid electrolyte–solid electrode electrostatic interactions. Recently, the focus of interfaces shifts to the cation-water interaction, which is not included in the conventionally pondered. This interaction reportedly plays a pivotal role in water-involved reactions because it affects the intramolecular O-H bond of water molecules. Herein, we demonstrate a correlation between the thermodynamics of water dissociation and the cation species using hydrogen evolution as a probing reaction. Surprisingly, a significantly improved onset potential of water reduction is observed by using multivalent cations, especially, the lowest solubility product (Ksp) towards metal hydroxide, Al3+. It infers that the metal cations interact directly or indirectly with water molecules to form the metal hydroxide, subsequently providing sufficient reactant, i.e., H+, at the electrode surface in the more positive potential region. By correlating electrochemical and spectroscopic results, we surmise that the presence of cations in weak acid conditions causes the formation of metal hydroxide compared to the absence of cations, resulting in a promoted onset potential of water reduction.

Design and synthesis of fluorescence-labeled nucleotide with a cleavable aryl-triazene linker for DNA sequencing by synthesis

A novel acid-cleavable triazene linker was synthesized and then reacted with modified 2′-deoxyuridine triphosphate (dUTP), followed by Cy3 NHS ester, the final product serves as an excellent reversible terminator for DNA sequencing by synthesis (DNA SBS). The synthesized dye-labeled terminator incorporated into DNA strand faithfully in a DNA-elongation, and the fluorophore incorporated into DNA strands was cleaved completely under weak acidic conditions within short time. Further the first cleaved product can be incorporated with 100% efficiency for the second time. These preliminary evaluations show that the triazene reversible terminator has a great potential value in DNA sequencing.

Flotation separation of ilmenite and titanaugite modified by Fe2+-assisted peroxymonosulfate oxidation: Performance and activation mechanism

Efficient separation of ilmenite and titanaugite has always been recognized challenge in modern mineral processing. The use of a heterogeneous Fenton-like oxidation process composed of peroxymonosulfate (PMS) and Fe2+ is promising to address this issue. Flotation findings indicated that effective recovery of ilmenite could be achieved under weak acidic conditions, and a TiO2 recovery of 81.56 % and a grade of 32.16 % concentrate was collected. A series of characterization analyses confirmed that the PMS-Fe2+-mediated Fenton-like reaction in the ilmenite system generated more •OH and SO4•- radicals, which oxidized Fe2+ to Fe3+ on its surface, thus improving the active sites on ilmenite surface. Moreover, PMS-Fe2+ promoted the positive shift of surface charge on ilmenite, facilitating NaOL adsorption and making the surface more hydrophobic. NaOL primarily interacted with Fe active sites on the ilmenite surface and Mg2+ and Ca2+ active sites on the titanaugite surface in the formation as chemisorption. Thus, PMS-Fe2+ activated ilmenite mainly via augmenting the quantity and reactivity of Fe active sites on the surface. In summary, these findings provide the innovative pathways to implement the advanced oxidation processes in mineral flotation.

Walnut Shell Biomass Triggered Formation of Fe3C-Biochar Composite for Removal of Diclofenac by Activating Percarbonate

Percarbonate (SPC) as a promising substitute for liquid H2O2 has many advantages in the application of in situ chemical oxidation (ISCO). Developing efficient, cost effective and environmentally friendly catalysts for SPC activation plays the key role in promoting the development of SPC-based ISCO. Herein, the walnut shell biomass was combined with ferric nitrate for the catalytic synthesis of Fe3C@biochar composite (Fe3C@WSB), which demonstrated high efficiency in activating SPC for the removal of diclofenac (DCF). The Fe3C showed average crystallite size of 32.6 nm and the composite Fe3C@WSB demonstrated strong adsorptivity. The prepared Fe3C@WSB could activate both SPC and H2O2 with high efficiency at ca. pH 3 with extremely low leaching of iron, while in a weak acidic condition, higher efficiency of DCF removal was obtained in the Fe3C@WSB/SPC process than in the Fe3C@WSB/H2O2 process. Moreover, the Fe3C@WSB/SPC and Fe3C@WSB/H2O2 processes did not show significant differences when supplied with varying amounts of catalyst or oxidant, but the Fe3C@WSB/SPC process exhibited stronger capability in dealing with relatively highly concentrated DCF solution. Based on quenching experiments and electron spin resonance (ESR) analysis, heterogeneous activation of SPC was assumed as the dominant route for DCF degradation, and both the oxidation by radicals, including •OH, •O2− and CO3•−, combined with electron transfer pathway contributed to DCF degradation in the Fe3C@WSB/SPC process. The cycling experiment results also revealed the stability of Fe3C@WSB. This work may cast some light on the development of efficient catalysts for the activation of SPC.

Synergistically enhanced heterogeneous activation of dissolved oxygen for aqueous carbamazepine degradation over S(III) coupled with siderite

The wide occurrence of emerging contaminants (ECs) was drawing more attention due to the potential hazard and threat on human and environment. Carbamazepine (CBZ) is a widely prescribed medication that has garnered considerable research interest with the exposures exceeding the environmental carrying capacity. We have established the innovative heterogeneous advanced oxidation process (AOPs) based on the activated dissolved oxygen (DO) coupled with S(III) and natural iron ore (siderite). In S(III)/O2/siderite system, we investigated the degradation efficiency, reactive species generation mechanism, and degradation pathway of CBZ. CBZ degradation and mineralization rate were 90% above and ∼15% with the reaction time of 40 min. The degradation of CBZ conformed to a pseudo-first-order kinetic model, with an activation energy determination of 76.36 kJ/mol. The optimal initial solution pH was the weak acid condition (pH = 4–6) for CBZ degradation. Moreover, the inhibition effects of coexisting substance including Cl−, HCO3−, and natural organic matter (NOM) on CBZ removal were observed, while the coexisted SO42− exhibited no significant influence. In addition, the reactive species generated in S(III)/O2/siderite system were predominantly identified as sulfate radical (SO4∙-) and hydroxyl radical (∙OH). The crucial intermediate complexes, Fe(III)S(IV)O3(+) and Fe(II)HS(IV)O3(+), was proposed to form in the initial stages of the reaction, which upon decomposition, yielded SO4∙- along with other reactive species. The degradation pathway of CBZ primarily involved deamination, oxidative ring-opening, hydroxylation, decarboxylation, and ketone degradation processes. This work provides the effective approach for the CBZ degradation with the mild reaction conditions and the sustainable technology for ECs treatment and control.

The impact of gold mining activities: understanding the dynamics of cyanide in river ecosystems in Ecuador.

Understanding the behavior of cyanide in rivers is of utmost importance as it has a direct impact on the health of people who depend on these water sources. Cyanide contamination from gold mining activities poses a significant environmental threat to river ecosystems, particularly in southern Ecuador. This study aimed to investigate the behavior of cyanide when it enters contact with other metals in these rivers. Simulations were conducted to determine the speciation of cyanide, mercury, arsenic, lead, and manganese in a study area, taking into account the water temperature and pH at four locations. The findings revealed that CN-and HCN(aq) species were present in the research area. Additionally, mercury-cyanide (Hg(CN)2(aq), Hg(CN)3-), and manganese-cyanide (MnCN+) complexes were identified 3km downriver from the site where the mining activity is higher. These metal-cyanide complexes tend to dissociate quickly under weak acidic conditions, making them hazardous to the environment. This research is crucial, not only for the environment but also for human health, as it allows to predict toxicity risks for people supplied with this water source, emphasizing the potential harm to human health. This study highlights the importance of stringent regulations and effective monitoring practices to mitigate cyanide contamination and safeguard environmental and occupational health.

Efficient flotation separation of chalcopyrite from molybdenite and adsorption mechanism by green depressant pyrogallic acid

Chalcopyrite and molybdenite are the primary minerals from which copper and molybdenum are extracted. However, the separation of chalcopyrite and molybdenite is restricted because of their inherent floatability. This study explores the separation effects of the addition of a green depressant, pyrogallic acid (PA), on chalcopyrite and molybdenite. The feasibility of flotation separation was verified by flotations tests with chalcopyrite and molybdenite under weak acid conditions at pH 6. The zeta potential and total organic carbon (TOC) illustrated that PA could have strong chemical adsorption on the surface of chalcopyrite and weak adsorption on the surface of molybdenite. Fourier-transform infrared (FTIR) spectroscopy illustrated that PA had a strong redox reaction at the surface of chalcopyrite. X-ray photoelectron spectroscopy (XPS) results illustrated that the reaction occurred through the generation of Cu/Fe-OH complexes covered on the chalcopyrite surface to reduce the active adsorption sites, which led to a decrease in the collection capacity for chalcopyrite. Moreover, time-of-flight secondary ion mass spectrometry (ToF-SIMS) results showed that the Cu and Fe sites on the surface of chalcopyrite were oxidized by PA. The intensities of FeOH− and CuOH− were found to be enhanced in the fragmentation peaks. Accordingly, a new selective adsorption model of PA on chalcopyrite and molybdenite was proposed.

Fabrication of oxygen-releasing dextran microgels by droplet-based microfluidic method.

In the tissue engineering field, the supply of oxygen to three-dimensional (3D) tissues is an important aspect to avoid necrosis due to hypoxia. Although oxygen-releasing bulk materials containing calcium peroxide (CaO2, CP) have attracted much attention, micrometer-sized oxygen-releasing soft materials would be advantageous because of their highly controllable structures, which can be applied for cell scaffolds, injectable materials, and bioink components in 3D bioprinting. In this study, oxygen-releasing microgels were fabricated via a droplet-based microfluidic system. Homogeneous, monodisperse and stable oxygen-releasing microgels were obtained by photo-crosslinking of droplets composed of biocompatible dextran modified with methacrylate groups and CP nanoparticles as an oxygen source. We also used our microfluidic system for the in situ amorphous calcium carbonate (CaCO3, ACC) formation on the surface of CP nanoparticles to achieve the controlled release of oxygen from the microgel. Oxygen release from an ACC-CP microgel in a neutral cell culture medium was suppressed because incorporation of CP in the ACC suppressed the reaction with water. Strikingly, stimuli to dissolve ACC such as a weak acidic conditions triggered the oxygen release from microgels loaded with ACC-CP, as the dissolution of CaCO3 allows CP to react. Taken together, applications of this new class of biomaterials for tissue engineering are greatly anticipated. In addition, the developed microfluidic system can be used for a variety of oxygen-releasing microgels by changing the substrates of the hydrogel network.

Intensifying inactivation strategies: Insights into the role of ultrasound on the inactivation of antibiotic resistant Acinetobacter baumannii via Photo-Fenton reaction

Improvisation of the contemporary water treatment technologies is critical not only to prevent water borne diseases but also to augment the available water sources. Here, a systematic study is effectuated to comprehend the upswing in the inactivation efficiency of Photo-Fenton (PF) chemistry induced by ultrasound (US) against antibiotic resistant (ABR) Acinetobacter baumannii (A. baumannii). Inactivation of A. baumannii (≈5×106 CFU/mL) was noticed within 75 and 105 min of US assisted PF (SPF) and PF processes respectively using 20 mg/L of H2O2 and 2 mg/L of Fe2+. It was interesting to notice that the PF reaction was effective under weak acidic condition (pH=3 and 5.5) whereas SPF process was realized over a wide pH range (3, 5.5, 7 and 9). No reactivation of the bacteria was found in both the processes till 96 h suggesting the impairment of not only the bacterial cell membrane but also the intracellular components. Experimental results although has suggested the generation of several reactive oxygen species (ROS), the inactivation mechanism was suggested to be dominated by the H2O2 and •OH. The damage caused to the bacterial cell membranes by the synergistic role of US and ROS was observed in the electron microscopy images. Comparative transcriptomic analysis has indicated the upregulation of genes regulating the LPS assembly proteins (Lpt A, B, C) and Pls B, Pgs A and Pal genes regulating the phospholipid synthesis which are known to regulate the stress induced response in bacteria. The SPF process was further validated with real water samples and the treated water was not found to have remarkable toxic effect on the in-vivo animal which endorse its candidature for future applications.

Microenvironment‐adaptive nanodecoy synergizes bacterial eradication, inflammation alleviation, and immunomodulation in promoting biofilm‐associated diabetic chronic wound healing cascade

AbstractThe presence of bacterial biofilms and the occurrence of excessive inflammatory response greatly imped the healing process of chronic wounds in diabetic patients. However, effective strategies to simultaneously address these issues are still lacking. Here, a microenvironment‐adaptive nanodecoy (GC@Pd) is constructed via the coordination and in situ reduction of palladium ions on gallic acid‐modified chitosan (GC) to promote wound healing by synergistic biofilm eradication, inflammation alleviation, and immunoregulation. During the weakly acidic conditions of the biofilm infection stage, GC@Pd serves as a nanodecoy to induce bacterial aggregation. Subsequently, through its oxidase‐like activity generating reactive oxygen species and the hyperthermia from photothermal effects, it effectively eliminates the biofilm. As the local microenvironment of diabetic wounds transitions to an alkaline inflammatory state, the enzyme‐like activity of GC@Pd adapts to catalase‐like activity, effectively eliminating reactive oxygen species at the site of inflammation. Additionally, GC@Pd could selectively capture pro‐inflammatory cytokines through Michael addition reactions. In vivo experiments and transcriptomic analysis confirmed that GC@Pd could accelerate the wound transition from inflammatory to proliferative phase by eliminating biofilm infection and reducing the inflammatory response, thus promoting diabetic chronic wound healing. The nanodecoy provides a potential therapeutic strategy for treating biofilm‐infected diabetic chronic wounds.

Biochar assisted synthesis of α-MnO2 nanowires with superior performance for non-radical activation of peroxymonosulfate

Non-radical activation of peroxymonosulfate (PMS) is a promising water treatment technology for removing refractory organics, but its mechanism is still ambiguous and the development of highly efficient catalyst is still a challenge. Herein, α-MnO2 nanowires were synthesized by a hydrothermal method with the assistance of biochar and their performance for PMS activation was studied. The characterization results show that the addition of biochar had little effect on the crystal phase and valence state of MnO2 but significantly reduced the size of nanowires. These nanowires had mesoporous structure, high surface area and oxidation ability, resulting in their superior performance for removing organic pollutants with PMS activation. The degradation of phenol by α-MnO2-PMS followed first order kinetics with an activation energy of 14.82 kJ mol−1. Electron paramagnetic resonance and radical scavenging experiments demonstrated that this activation process followed the non-radical mechanism. The quenching effect of scavengers led to the misleading role of singlet oxygen. In fact, surface activated PMS (MnO2–PMS*) rather than singlet oxygen was the reactive species. Weak acidic condition was conducive for the formation of MnO2–PMS* complexes. This catalyst exhibited good reusability and high activity for removing various organic pollutants, and the common substances in real water had little effect on its performance, suggesting its potential application in wastewater treatment.

Evaluation of gamma rays shielding properties of bismuth tungstate with different morphologies

To develop lead-free gamma-ray shielding material, bismuth tungstate (Bi2WO6) nanocrystals were synthesized under different conditions of precursor solution by hydrothermal method and composite material based on polyurethane and bismuth tungstate nanocrystals were prepared and evaluated using gamma ray sources in this study. The effects of crystal structure and morphology on the gamma ray shielding properties of bismuth tungstate were specially investigated. Results indicated that pH value of precursors solution had significant effect on the synthesis of bismuth tungstate: orthorhombic Bi2WO6 were obtained under acidic or neutral conditions while tetragonal Bi0.875W0.125O1.6875 were obtained under strongly alkaline condition. With the increase of pH value, the morphology of bismuth tungstate changed from flower-like microspheres to persimmon-like microstructures, and then to randomly stacked nanosheets. Bismuth tungstate nanocrystals were added to polyurethane to prepare flexible gamma-ray shielding material and the gamma ray shielding properties were also tested with energy of 59.5 keV, 81.0 keV and 121.8 keV. For orthorhombic persimmon-like bismuth tungstate (Bi2WO6) which were produced under weak acidic or neutral condition (pH = 2, 5, 7), it was found that the linear attenuation coefficient of gamma ray grew by about 8 % when pH changing from 2 to 7 for all energy tested. While for tetragonal bismuth tungstate (Bi0.875W0.125O1.6875), weakly alkaline condition (pH = 9) induced significant decrease (9 %@59.5 keV, 17 %@81.0 keV and 11 %121.8 keV) of linear attenuation coefficient compared with neutral condition, which could be explained by the dramatic crystal structure change of bismuth tungstate. More alkaline synthesizing condition would make finer granularity of bismuth tungstate and the linear attenuation coefficient increased when pH change from 9 to 12. In addition, obvious differences of mechanical properties were also observed between the composites prepared using different crystalline bismuth tungstates. The results of this study provide a reference for the development of new flexible radiation shielding materials with non-toxicity, light weight and high efficiency.

Enterobacter sp. HIT-SHJ4 isolated from wetland with carbon, nitrogen and sulfur co-metabolism and its implication for bioremediation

Both autotrophic and heterotrophic denitrification are known as important bioprocesses of microbe-mediated nitrogen cycle in natural ecosystems. Actually, mixotrophic denitrification co-driven by organic matter and reduced sulfur substances are also common, especially in hypoxic environments such as estuarine sediments. However, carbon, nitrogen and sulfur co-metabolism during mixotrophic denitrification in natural water ecosystems has rarely been reported in detail. Therefore, this study investigated the co-metabolism of carbon, nitrogen and sulfur using samples collected from four distinct natural water ecosystems. Results demonstrated that samples from various sources all exhibited the ability for co-metabolism of carbon, nitrogen and sulfur. Microbial community analysis showed that Pseudomonas and Paracoccus were dominant bacteria ranging from 65.6% to 75.5% in mixotrophic environment. Enterobacter sp. HIT-SHJ4, a mixotrophic denitrifying strain which owned the capacity for co-metabolism of carbon, nitrogen and sulfur, was isolated and reported here for the first time. The strain preferred methanol as its carbon source and demonstrated remarkable efficiency for removing sulfide and nitrate with below 100 mg/L sulfide. Under weak acid conditions (pH 6.5–7.0), it exhibited enhanced capability in converting sulfide to elemental sulfur. Its bioactivity was evident within a temperature from 25 °C to 40 °C and C/N ratios from 0.75 to 3. This study confirmed the widespread presence of microbial-mediated synergistic carbon, nitrogen and sulfur metabolism in natural aquatic ecosystems. HIT-SHJ4 emerges as a novel strain, shedding light on carbon, nitrogen and sulfur co-metabolism in natural water bodies. Furthermore, it also serves as a promising candidate microorganism for in-situ ecological remediation, particularly in dealing with contamination posed by nitrate, sulfide, and organic matter.

Degradation of sodium dodecylbenzene sulfonate (SDBS) and high efficiency treatment of real grey water by TiO2-loaded stainless steel mesh under VUV irradiation

Reusing treated greywater indoors in buildings is an advanced strategy to increase the utilization of limited water resources, but currently there is a lack of feasible technologies for efficiently purifying greywater indoors. In this study, we construct the heterogeneous TiO2-stainless steel mesh (SSM) interface with photocatalytic degradation of sodium dodecylbenzene sulfonate (SDBS) by under vacuum ultraviolet (VUV) irradiation. At the initial SDBS of 10 mg/L, the degradation rates of SDBS with UV/TiO2-SSM and VUV/TiO2-SSM process were 53 % and 74 % respectively within 50 min. The results of specific scavengers experiments and EPR analysis revealed that the ·OH, h+ and direct photolysis contributed to SDBS degradation and mineralization. The degradation rate of SDBS in VUV/TiO2-SSM process was higher at weak acid or weak alkali conditions, while the performance of UV/TiO2-SSM process was better at alkaline conditions. Both Cl− and HCO3− could inhibit SDBS degradation, while SO42− slightly promoted the degradation. Active oxygen species mainly degrade SDBS in two ways: by attacking the α carbon, β carbon, or branched chain carbon on the alkane chain; or by attacking the adjacent carbon on the alkane chain, resulting in the formation of three branch forms of products. The toxicity of the intermediate products shows a decreasing or stable trend. The experiment shows that UV or VUV photocatalytic TiO2-SSM has a good prospect of removing anionic surfactant in the real greywater. This study provides strategies for the development and design of indoor water reuse technologies and devices in buildings.

A pH-responsive single-atom nanozyme for photothermal-augmented nanocatalytic tumor therapy

Based on the physiological conditions of the tumor microenvironment (TME), many effective therapeutic strategies have been reported by using nanocatalysts. The main challenge is the insufficient catalytic activity of nanocatalysts within the acidic TME, significantly constraining their therapeutic efficacy. Herein, a pH-responsive bifunctional platform is developed with multiple enzyme-like catalytic activities for synergistic tumor therapy by integrating Rh single atoms nanozymes (SA-Rh nanozymes) with photothermal therapy (PTT). The SA-Rh nanozymes display peroxidase-mimicking activities within tumor cells, inducing a synergistic effect of enhanced reactive oxygen species generation for collaborative cancer therapy involving both chemodynamic therapy and PTT. Additionally, SA-Rh nanozymes exhibit catalase mimicking activities, enabling the generation of oxygen, and facilitating efficient nanozyme catalytic therapy in a substrate-cycle manner. Moreover, the catalytic efficiency of SA-Rh nanozymes is found to be higher under weak acidic conditions (pH=6.0) compared to neutral conditions (pH=7.4), thereby enabling the maintenance of catalytic activity in an acidic environment. The incorporation of this feature enhances its catalytic activity within the TME, optimizing the efficacy of nanozyme. The remarkable near-infrared I region absorption capability confers SA-Rh nanozymes with exceptional PTT performance, achieving an impressive efficiency of 34.1 %. Therefore, the SA-Rh nanozymes exhibit a remarkable ability to induce apoptosis in cancer cells through synergistic CDT and PTT modalities, effectively overcoming the shortcomings of current nanozyme catalytic therapy.

Advanced Insulin Synthesis by One-pot/Stepwise Disulfide Bond Formation Enabled by S-Protected Cysteine Sulfoxide.

An advanced insulin synthesis is presented that utilizes one-pot/stepwise disulfide bond formation enabled by acid-activated S-protected cysteine sulfoxides in the presence of chloride anion. S-chlorocysteine generated from cysteine sulfoxides reacts with an S-protected cysteine to afford S-sulfenylsulfonium cation, which then furnishes the disulfide or reversely returns to the starting materials depending on the S-protection employed and the reaction conditions. Use of S-acetamidomethyl cysteine (Cys(Acm)) and its sulfoxide (Cys(Acm)(O)) selectively give the disulfide under weak acid conditions in the presence of MgCl2 even if S-p-methoxybenzyl cysteine (Cys(MBzl)) and its sulfoxide (Cys(MBzl)(O)) are also present. In contrast, the S-MBzl pair yields the disulfide under more acidic conditions in the presence of a chloride anion source. These reaction conditions allowed a one-pot insulin synthesis. Additionally, lipidated insulin was prepared by a one-pot disulfide-bonding/lipidation sequence.

Strong, tough, high-release, and antibacterial nanocellulose hydrogel for refrigerated chicken preservation

Enormous amounts of food resources are annually wasted because of microbial contamination, highlighting the critical role of effective food packaging in preventing such losses. However, traditional food packaging faces several limitations, such as low mechanical strength, poor fatigue resistance, and low water retention. In this study, we aimed to prepare nanocellulose hydrogels with enhanced stretchability, fatigue resistance, high water retention, and antibacterial properties using soy hull nanocellulose (SHNC), polyvinyl alcohol (PVA), sodium alginate (SA), and tannic acid (TA) as raw materials. These hydrogels were applied in food packaging to extend the shelf life of refrigerated chicken. The structure and properties (e.g., mechanical, antibacterial, and barrier properties) of these hydrogels were characterized using different techniques. Fourier-transform infrared spectroscopy revealed the presence of hydrogen and ester bonds in the hydrogels, whereas scanning electron microscopy revealed the three-dimensional network structure of the hydrogels. Mechanical testing demonstrated that the SHNC/PVA/SA/TA-2 hydrogel exhibited excellent tensile properties (elongation = 160 %), viscoelasticity (storage modulus of 1000 Pa), and mechanical strength (compressive strength = 10 kPa; tensile strength = 0.35 MPa). Moreover, under weak acidic and alkaline conditions, the ester bonds of the hydrogel broke down with an increase in pH, improving its swelling and release properties. The SHNC/PVA/SA/TA-2 hydrogel displayed an equilibrium swelling ratio exceeding 300 %, with a release rate of >80 % for the bioactive substance TA. Notably, antibacterial testing showed that the SHNC/PVA/SA/TA-2 hydrogel effectively deactivated Staphylococcus aureus and Escherichia coli, prolonging the shelf life of refrigerated chicken to 10 d. Therefore, the SHNC/PVA/SA/TA hydrogels can be used in food packaging to extend the shelf life of refrigerated meat products. Their cost-effectiveness and simple preparation make them suitable for various applications in the food industry.

Acid tolerance response of Salmonella during the squid storage and its amine production capacity analysis.

Salmonella exhibits a strong inducible acid tolerance response (ATR) under weak acid conditions, and can also induce high-risk strains that are highly toxic, acid resistant, and osmotic pressure resistant to aquatic products. However, the induction mechanism is not yet clear. Therefore, this study aims to simulate the slightly acidic, low-temperature, and high-protein environment during squid processing and storage. Through λRed gene knockout, exploring the effects of low-acid induction, long-term low-temperature storage, and two-component regulation on Salmonella ATR. In this study, we found the two-component system, PhoP/PhoQ and PmrA/PmrB in Salmonella regulates the amino acid metabolism system and improves bacterial acid tolerance by controlling arginine and lysine. Compared with the two indicators of total biogenic amine and diamine content, biogenic amine index and quality index were more suitable for evaluating the quality of aquatic products. The result showed that low-temperature treatment could inhibit Salmonella-induced ATR, which further explained the ATR mechanism from the amino acid metabolism.