Physiological pH Research Articles

Randomized trial of dietary acid reduction and acid-base status of patients with CKD and normal eGFR

IntroductionModern acid-producing diets in patients with stage G3-G5 chronic kidney disease (CKD) can cause severe acid accumulation with metabolic acidosis and less severe accumulation causing eubicarbonatemic acidosis in stages G2-G3, each with kidney injury. The impact of these diets on acid accumulation in those with CKD but normal eGFR (G1) is unclear. MethodsWe assessed whether acid accumulation occurs in patients with CKD and normal eGFR, and if added base-producing fruits and vegetables (F&V) or oral NaHCO3 (HCO3-) reduces acid accumulation and/or lowers kidney injury. We randomized 153 macroalbuminuric, non-diabetic, G1 (mean eGFR = 101 ml/min/1.73 m2) participants with hypertension-associated CKD to receive F&Vs in amounts to reduce dietary acid intake 50% (F&V, n=51), oral NaHCO3 to match alkali intake of F&V (HCO3-, n=51), or usual care (UC, n=51) for five years. We assessed acid accumulation by comparing observed to expected increase in plasma total CO2 in response to retained bicarbonate (dose minus urine bicarbonate excretion) two hours after an oral NaHCO3 bolus. ResultsBaseline acid accumulation, eGFR, urine excretion of albumin, N-acetyl-β-D-glucosamine, and angiotensinogen were not different among groups. Five-year acid accumulation [mean(SD)] was lower in F&V [-1.2 (11.0) mmoles] and HCO3- [-1.7 (10.8) mmoles] than UC [5.2 (10.3) mmoles, p<0.003)], consistent with lower acid accumulation in F&V and HCO3-. Five-year urine excretion of albumin, N-acetyl-β-D-glucosamine, and angiotensinogen were lower in F&V and HCO3- than UC, consistent with less kidney injury. ConclusionsDietary acid reduction reduces acid accumulation and kidney injury in patients with CKD and normal eGFR.

Enhanced activity of split trehalase biosensors by interspecies domain combineering.

The split trehalase biosensor has potential as a versatile diagnostic technology. Split enzymes are engineered proteins, divided into inactive fragments, which can reassemble and regain activity when brought together by an analyte. The split TreA biosensor requires no sample processing and produces stable signals (in the form of glucose). Split trehalase reagents can function in blood, but periplasmic trehalase of E.coli requires blood acidification for maximal activity. The objective of this study was to obtain split trehalase with near physiological pH optimum. For this purpose, periplasmic trehalases of Cellvibrio spp. with higher activity at neutral pH, were split in analogy with the E. coli TreA into hood and catalytic domains. However, these split trehalases displayed self-complementation due to spontaneous reassembly. In contrast, when catalytic domains of Cellvibrio trehalases were combined with E.coli hood domains, these hybrids displayed conditional complementation capacity when split trehalase fragments fused to immunoglobulin-binding protein G (STIGA) were used to quantify immunoglobulin concentrations. Other hybrid combinations of Cellvibrio spp. had increased activity compared to the cognate pairs, albeit with strong self-complementation. A mutagenesis analysis of residues responsible for self-complementation led to uncoupling of self-complementation from allostery. The Michaelis-Menten kinetics of Cellvibrio enzymes and fragment pairs confirmed improved activity of a mutated hybrid pair of Cellvibrio hood and catalytic domains at physiological pH. In conclusion, the improvements in pH optimum and activity, demonstrated with STIGA, can now be leveraged to enhance other variations of the split trehalase biosensor platform, broadening its utility for testing clinical samples.

Highly selective and sensitive N-amidothiourea-based fluorescence chemosensor for detecting Zn2+ ions and cell Imaging: Potential applications for plasma membrane detection

A “turn-on” fluorescent sensor L was developed for the selective detection of Zn2+ ions in biological settings. This sensor exhibited a specific response to Zn2+ ions, with a detection limit of 39 nM. Analyses through titration and Job’s plot confirmed that the formed complex has a 2:1 stoichiometry (L: Zn2+). The sensor displayed strong selectivity for Zn2+ over other metal ions, demonstrating a robust binding affinity while effectively reducing interference from heavy metals. The identification process was validated by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR) titrations, mass spectrometry (MS), and Density Functional Theory (DFT) calculations. Maximum fluorescence intensity was achieved upon interaction with Zn2+ ions within a physiological pH range of 7.0–7.5. Moreover, successful imaging experiments in HEK293 cells highlighted the sensor’s potential as a powerful tool for monitoring interactions at the plasma membrane.

Study on the physiological responses and tolerance mechanisms to subchronic carbonate alkalinity exposure in the gills of Paramisgurnus dabryanus

Given the reduction of freshwater resources, saline-alkaline aquaculture has emerged as an effective approach to expand the fishery's accessible space. High carbonate alkalinity (CA) is a major stressor for aquatic organisms in saline-alkaline environments. Paramisgurnus dabryanus is a potential species for culture in saline-alkaline water, making it an ideal model for investigating the physiological responses and tolerance mechanisms to CA exposure in freshwater fishes. In the current study, P. dabryanus were exposed to 15 and 30mmol/L NaHCO3, combining blood biochemical, gill histological, transcriptomic, and metabolomic methods for conjoint analysis of response mechanisms. After 28-d exposure, the gill ventilation frequency of P. dabryanus decreased significantly, gill lamellae twisted and atrophied, and gill filament epithelial cells proliferated, potentially limiting gas exchange, whereas the accessory air-breathing frequency increased significantly, possibly for greater oxygen uptake. Serum osmolality and blood pH remained relatively steady, while serum ammonia levels rose significantly. A total of 3718 differentially expressed genes (DEGs) and 205 differential metabolites (DMs) were identified between the control group and 30mmol/L NaHCO3 group, involved in ion transport (Na+/K+-ATPase, V-type ATPase, carbonic anhydrase, and ABC transporters), ammonia transport (Rh glycoproteins and Aquaporins), amino acid metabolism, carbohydrate metabolism, and fatty acid metabolism. Furthermore, DEGs were significantly associated with cell-cell/ extracellular matrix interaction and protein synthesis. An integrated multi-omics analysis revealed the activation of carbon metabolism and TCA cycle. These results indicate that in response to CA exposure, P. dabryanus may facilitate carrier-mediated ion and ammonia transport to maintain the internal osmotic equilibrium and lessen the deleterious effects of blocked ammonia excretion. Meanwhile, amino acid metabolism and protein synthesis are disturbed, P. dabryanus can modulate carbohydrate catabolism to maintain energy homeostasis. The above findings provide novel insights into saline-alkaline adaptation in freshwater fishes, paving the way for future research and development of saline-alkaline-tolerant Cobitidae strains.

Synthesis, crystal structure and exploration of N,N'-(ethane-1,2-diyl)bis(4-acetylbenzenesulfonamide) (EDBABS) fabricated glassy carbon electrode as highly sensitive barium (Ba2+) sensor: An electrochemical approach

Environmental pollution spurred by dint of noxious chemicals and heavy metals has popped up as a pressing threat for present day community. In this study, we synthesized the N,N'-(ethane 1,2-diyl)bis(4-acetylbenzene-1-sulfonamide) (EDBABS) and N,N'-(cyclohexane-1,2-diyl)bis(4-acetylbenzenesulfonamide) (CDBABS) as bidentate chelating agents with the intention to detect the heavy metal cations in water systems. Conventional spectroscopic techniques such as UV-Vis spectroscopy, Fourier transform-infra red (FT-IR) spectroscopy, 1H-NMR and 13C-NMR in addition to single crystal X-ray diffraction studies were performed to expound structural characterization data of these newly synthesized non-reported bidentate chelating agents. After Characterization, a novel electrochemical current – potential (I-V) approach based on their modified GCEs was applied to detect the toxic cations in water systems. For this purpose, Keithley electrometer was employed as a constant voltage source. On the trail of fabricating an efficient as well as selective electrochemical sensor, for the detection of heavy metal cations in phosphate buffer system of pH = 7.0, EDBABS and CDBABS coupled with nafion as adhesive conducting binder were coated separately onto the Glassy Carbon Electrodes (GCEs). it was delineated that newly designed EDBABS/Nafion/GCE induced a high current response for Ba2+ cations in the presence of other interfering heavy metal cations (Y3+, Sn2+, Sb3+, Mn2+, Hg2+, Cr3+, As3+ and Ag+) than CDBABS/Nafion/GCE and found to be selective and sensitive towards Ba2+ cations, predominantly contributing towards environmental pollution. In order to optimize this newly designed EDBABS/Nafion/GCE as selective electrochemical Ba2+ cationic sensor, different analytical parameters such as sensitivity, limit of detection (LOD) at S/N of 3, limit of quantification (LOQ), and linear dynamic range (LDR) turned out to be satisfactory towards Ba2+ cations. The calibration curve emerged to be linear with a broad concentration range of Ba2+ cations from 0.1 nM to 0.01M and sensitivity was estimated as 3.481 × 10−3µAµM−1cm−2 in addition to (r2) as 0.9834, limit of detection (LOD) as 0.027nM (at S/N=3) and limit of quantification (LOQ) as 0.091nM. Within the realm of extensive environmental protection and public health care field, this work inducts a reliable and effective way for the fabrication of sensitive as well as selective cationic electrochemical sensors based on chelating agents which can be launched as an advanced approach for quick probing of heavy metal cations in water systems, reliably and effectively.

Tuning the Protonation Sensitivity of Weak Acidic Groups on a Zwitterionic Dendrimer for Selectively Targeting GD2-Overexpressed Tumor Cells in an Acidic Tumor Microenvironment.

Disialoganglioside (GD2) is one of the most popular overexpressed antigens for tumor cell targeting. However, GD2-specific antibodies often show unintended targeting to GD2-expressing health-maintaining cells due to the comparable binding affinities both at physiological pH and in a slightly acidic tumor microenvironment (TME). In this work, an affinity-switchable zwitterionic PAMAM G5 dendrimer (G5-3S) is developed for selective binding to GD2 only in a slightly acidic TME. It has 3 sulfonic groups, 128 carboxylic groups, and 125 amino groups on the surface. This affinity switch is realized by multiple hydrogen bond (H-bond) formation between protonated carboxylic groups surrounding a sulfonic group and overexpressed GD2 clusters on the tumor cell membrane in the slightly acidic TME, whereas there is no stable H-bond formation at physiological pH. Thus, G5-3S shows superior selectivity to GD2-overexpressed tumor cells over anti-GD2 antibodies by avoiding targeting GD2-expressing health-maintaining cells at physiological pH. This suggests that G5-3S is a promising candidate for GD2-overexpressed cancer treatment.

Assessing the Impact of Riparian Buffer Systems on Water Quality Improvement and Infiltration Enhancement: Integration of SWAT-MODFLOW and SWAT-REMM

Objectives:This study aims to assess the effect of riparian buffer system on the water quality improvement and infiltration enhancement in the upper Sinduncheon watershed by integrating the SWAT-MODFLOW and SWAT- REMM models.Methods:The study focused on three subbasins in the upper Sinduncheon watershed. Streamflow and groundwater level were simulated and relevant parameters were calibrated using SWAT-MODFLOW. Subsequently, the calibrated parameters were applied to SWAT-REMM to evaluate the effects of riparian buffer systems on the reduction of NO3-N and Suspended Solids (SS) and the enhancement of water infiltration. Riparian buffer scenarios with varying widths (9m, 21m, 27m). Results and Discussion:The results showed that the riparian buffer system led to significant reductions in NO3-N and SS. Specifically, a subbasin with the widest buffer (27m) showed the highest reduction efficiency (82.6% for NO3-N and 99.6% for SS). However, in a subbasin, despite having a wider buffer than other subbasin, the reduction efficiency was lower due to the presence of channelized pollutant inflow areas. Additionally, the riparian buffer increased rainfall infiltration by approximately 13%, contributing to the stabilization of baseflow.Conclusion:This study demonstrates that riparian buffer systems can significantly improve water quality and increase water infiltration in the upper Sinduncheon watershed. Future research should focus on developing tailored riparian buffer strategies that consider regional characteristics such as pollutant inflow patterns, land cover, and topography.

An Isoniazid-Based reversible Schiff base chemosensor for Multi-Analyte (Cu2+, Ni2+, Hg2+) detection

Isoniazid-based Schiff base N’-(furan-2-ylmethylene)isonicotinohydrazide (FINH) has been synthesized. FINH has proven its ability to selectively sense and respond to Cu2+, Ni2+, and Hg2+, which shows its potential as a chemosensor. UV–visible experiments, the absorption band (at 360 nm) of FINH shifted with the gradual addition of Cu2+, Ni2+, and Hg2+. A significant quenching in the emission band of FINH in fluorescence spectra has been observed with the addition of analytes at the physiological pH range. Cyclic voltammetric experiments have been conducted to determine the electron transfer process that occurs during the complexation of FINH with analytes. Moreover, the interactions of FINH-metal ions are reversible, and their reversible behavior has been demonstrated with the Na2EDTA solution. The binding insights among FINH and Cu2+, Ni2+, and Hg2+ are explained by IR spectral study. Additionally, the FINH works within the appreciable detection limit of 9.472 x 10−7 M (for Cu2+), 7.685 x 10−7 M (for Ni2+) and 2.411 x 10−7 M (for Hg2+), limit of quantitation of 3.15 x 10−6 M (for Cu2+), 2.561 x 10−6 M (for Ni2+) and 8.036 x 10−7 M (for Hg2+). Applying this isoniazid-based reversible chemosensor in analyzing real samples demonstrates its practicality and effectiveness for multi-analyte detection. This sensor could consistently measure metal ion concentrations in various environmental and biological samples, providing a valuable tool for monitoring pollutants and evaluating exposure risks.

Redox Biocatalysis in Lidocaine-based Hydrophobic Deep Eutectic Solvents: Non-conventional Media Outperform Aqueous Conditions.

Redox biocatalysis is an important pillar of the chemical industry. Yet, the enzymes' nature restricts most reactions to aqueous conditions, where the limited substrate solubility leads to unsustainable diluted biotranformations. Non-aqueous media represent a strategic solution to conduct intensified biocatalytic routes. Deep eutectic solvents (DESs) are designable solvents that can be customized to meet specific application needs. Within the large design space of combining DES components (and ratios), hydrophobic DESs hold the potential to be both enzyme-compatible - keeping the enzymes' hydration -, and solubilizers for hydrophobic reactants. We explored two hydrophobic DESs, lidocaine/oleic acid, and lidocaine/decanoic acid, as reaction media for carbonyl reduction catalyzed by horse liver alcohol dehydrogenase, focusing on the effect of water contents and on maximizing substrate loadings. Enzymes remained highly active and stable in the DESs with 20 wt.% buffer, whereas the reaction performance in DESs outperformed the pure buffer system with hydrophobic substrates (e.g., cinnamaldehyde to form the industrially relevant cinnamyl alcohol), with a 2-fold higher specific activity. Notably, the cinnamaldehyde reduction was for the first time performed at 800 mM (~100 g[[EQUATION]]L-1) with full conversion, which opens up new avenues to industrial applications of hydrophobic DESs for enzyme catalysis.

3D-printed NiMOF-MXene nanocomposite-based sensing chip with enhanced electrocatalytic response for glucose detection in human blood sample in physiological pH

3D-printed NiMOF-MXene nanocomposite-based sensing chip with enhanced electrocatalytic response for glucose detection in human blood sample in physiological pH

Factors associated with neurological outcomes in patients experiencing out-of-hospital cardiac arrest and severe acidaemia: retrospective analysis of a nation-wide registry

Background and objectiveAcidaemia is common among individuals who experience out-of-hospital cardiac arrest (OHCA). While severe acidaemia is a strong predictor of unfavourable outcomes, a subset of patients exhibits dramatic recovery. Despite these conflicting outcomes, little is known about the factors associated with neurological outcomes in those who experience OHCA with severe acidaemia. MethodsThis retrospective analysis used data from a Japanese multicentre nationwide database, the Japanese Association for Acute Medicine OHCA Registry. The analysis included data from adult patients with OHCA for whom blood pH data were available upon arrival to hospital. The primary outcome was 30-day survival with favourable neurological outcomes, defined as a Glasgow-Pittsburgh cerebral performance category score of 1 or 2. Patients were categorised with severe acidaemia if their blood pH was ≤ 6.8. Factors associated with favourable outcomes were investigated using multiple logistic regression analysis. ResultsData from 49,044 patients were included in the analysis, of whom 16,620 exhibited severe acidaemia with a median pH of 6.70 (interquartile range [IQR] 6.61–6.76], and 0.5% (86/16,620) experienced a neurologically favourable outcome. After adjustment for important prognostic factors, witnessed status exhibited a strong association with favourable neurological outcome (adjusted odds ratio [aOR] 6.46 [95% confidence interval (CI) 2.64–15.8]), while initial blood pH exhibited no significant association (aOR 0.90 with every 0.1 unit increase [95% CI 0.71–1.14]). ConclusionAlthough the number is small, a notable number of patients with severe acidaemia exhibited good neurological recovery. Witness status was critical for the prognosis of these patients.

Impact of Milk pH and Fat Content on the Prediction of Milk-to-Plasma Ratio: Knowledge Gap and Considerations for Lactation Study Design and Interpretation.

Different empirical lactation models have been published to predict the milk-to-plasma (M/P) ratio of drugs to gain knowledge on the extent of drug distribution to the breastmilk. M/P ratios will likely vary across the lactation period due to differences in physiological milk pH and fat content, which are not routinely reported in clinical lactation pharmacokinetic studies. This work aims to evaluate the sensitivity of two (a theory-based phase distribution and a log-transformed regression) lactation models for M/P prediction at different physiological milk pH and fat content. A literature search was conducted to collate reported M/P ratios for different drugs and their physicochemical parameters required for the prediction of the M/P ratio. Two distribution models were used for M/P ratio predictions. The M/P ratio of drugs was predicted under the physiological milk pHs of 6.8, 7.0, 7.2, and 7.4 and at of 1%, 3%, and 6% fat content. Calculated M/P ratios were compared with the observed M/P ratios. A total of 200 M/P ratios for 130 compounds (40 acids and 90 bases) were collected from clinical studies and included in the analysis. For both model, precision decreases and bias increases outside the milk pH range 7.0-7.2 and fat contents more than 3%. Significant variability exists in the observed M/P ratios. Both milk pH and fat content are important parameters for model prediction. Calculated M/P ratios are influenced by multiple covariates, including milk pH and fat content. The phase distribution model is less sensitive to these covariates than the log-transformed model, especially for acidic compounds. For complex matrices such as breastmilk, the actual physiological parameters of the sampled milk, at least milk fat and pH, and their distributions are required covariates to improve the prediction outcomes, design lactation pharmacokinetic studies, and inform the potential breastfed infant dose.

Water-Soluble Chitosan-Europium Hybrid Sensor for Singlet Oxygen Detection.

The ability to effectively monitor singlet oxygen (1O2) with fluorescence probes in biological systems is severely restricted mainly by the background autofluorescence of these systems. Though the application of lanthanide complexes as 1O2 monitors successfully resolves this problem with time-gated luminescence measurements, the insolubility of these complexes in an aqueous medium heavily limits their application in biological systems. Here, we present a water-soluble 1O2 sensor based on a chitosan-europium hybrid material. A procedure for the modification of chitosan to expand its solubility to neutral and basic pH, while maintaining its free active amine groups, is described. These are then coupled covalently to a europium-based probe for the detection of 1O2. The resulting hybrid sensor is readily soluble in water across the pH scale and efficiently signals the presence of 1O2 at physiological pH, with the characteristic Eu3+ emission at 611 nm yielding up to a 15-fold increase in emission intensity and a decay time of 332 μs. Being of particular interest for time-gated measurements, this long decay time, coupled with the biocompatibility of chitosan, describes a material with potential biological applications, where 1O2 plays a vital role.

Phylogenomic analysis of glutamine synthetase gene family in Helianthus annuus L.

Glutamine synthetase is one of the predominant enzymes in nitrogen metabolism. In developing leaves, glutamine is mainly produced in chloroplasts by the activity of the GS2 isoenzyme. It catalyzes glutamine synthesis from glutamate and ammonia in an ATP-dependent reaction. The genes encoding glutamine synthetase play a crucial role in ammonia and glutamate detoxification, acid-base homeostasis, cell signaling, and cell proliferation. The gene family responsible for producing glutamine synthetase has been previously documented in model plants like Arabidopsis. Nevertheless, there has been no exploration into its existence and attributes in oilseed crops like sunflower (Helianthus annuus L.). This study thoroughly analyzes, gene structure, conserved motifs, chromosomal location, phylogenetic relationships, and expression patterns to identify the glutamine synthetase genes in H. annuus. Our findings unveiled 19 genes encoding glutamine synthetase within the H. annuus genome. These genes were distributed across 11 chromosomes of H. annuus. Furthermore, we examined the expression patterns of all the HaGS genes using RNA-seq datasets, specifically focusing on their response to biotic and abiotic stress conditions. Under biotic stress, H. annuus expresses genes for mycorrhizal fungi named Rhizoglomus irregulare at four days post inflorescence (dpi) and 16 dpi. Under abiotic stress, the effect of drought and hormones was investigated. In drought, one gene, HaGS6D, showed the highest expression in the leaf. Meanwhile, in roots, gene HaGS7B showed the highest expression. Under hormonal stress, the effects of auxin, brassinosteroid, and cytokinin were studied on the leaf. For auxin, the gene HaGS7C showed the highest expression. For brassinosteroid, the gene HaGS7D showed the highest expression; for cytokinin, the gene HaGS6E showed the highest expression. Thus, these findings can significantly contribute to our understanding of the arrangement of glutamine synthetase genes in H. annuus and offer valuable insights for developing of drought-resistant cultivars of this species.

A NOVEL GOLD NANOPARTICLE‐IONIC LIQUID NANOSTRUCTURE MODIFIED Pleurotus Ostreatus BASED MICROBIAL BIOSENSOR SYSTEM FOR BISPHENOL A

The current study develops the first and novel gold nanoparticle‐ionic liquid nanostructure modified microbial biosensor based on &lt;i&gt;Pleurotus ostreatus&lt;/i&gt; for the sensitive determination of Bisphenol A &lt;b&gt;. &lt;/b&gt;In the construction of the microbial biosensor, lyophilized &lt;i&gt;P.ostreatus&lt;/i&gt; cells were modified with ionic liquid‐cysteamine mixture on a gold electrode which was modified with 1,6‐hexanedithiol and gold nanoparticle. The measurement principle of the biosensor is based on the detection of changes in current in a phosphate buffer system (pH 7.5, 50 mM and containing 5.0 mM K &lt;sub&gt;3&lt;/sub&gt;[Fe(CN) &lt;sub&gt;6&lt;/sub&gt;]) in the potential range of ‐0.2 to +0.6 V depending o

Enhancing glioblastoma cytotoxicity through encapsulating O6-benzylguanine and temozolomide in PEGylated liposomal nanocarrier: an in vitro study

Glioblastoma (GBM) (grade IV glioma) is the most fatal brain tumor, with a median survival of just 14 months despite current treatments. Temozolomide (TMZ), an alkylating agent used with radiation, faces challenges such as systemic toxicity, poor absorption, and drug resistance. To enhance TMZ effectiveness, we developed poly(ethylene glycol) (PEG) liposomes co-loaded with TMZ and O6-benzylguanine (O6-BG) for targeted glioma therapy. These liposomes, prepared using the thin-layer hydration method, had an average size of 146.33 ± 6.75 nm and a negative zeta potential (−49.6 ± 3.1 mV). Drug release was slower at physiological pH, with 66.84 ± 4.62% of TMZ and 69.70 ± 2.88% of O6-BG released, indicating stability at physiological conditions. The liposomes showed significantly higher cellular uptake (p < 0.05) than the free dye. The dual drug-loaded liposomes exhibited superior cytotoxicity against U87 glioma cells, with a lower IC50 value (3.99µg/mL) than the free drug combination, demonstrating enhanced anticancer efficacy. The liposome formulation induced higher apoptosis (19.42 ± 3.5%) by causing sub-G0/G1 cell cycle arrest. The novelty of our study lies in co-encapsulating TMZ and O6-BG within PEGylated liposomes, effectively overcoming drug resistance and improving targeted delivery for glioma treatment.

Effect of Artificial Saliva Modification on Corrosion Resistance of Metal Oxide Coatings on Co-Cr-Mo Dental Alloy.

Surface modifications not only improve the corrosion resistance of Co-Cr-Mo dental alloys (Bego Wirobond® C) but also ensure their long-term performance and reliability in dental applications. This paper describes the preparation of single-layer TiO2-ZrO2 sol-gel coatings on the Co-Cr-Mo dental alloy using the method of dip-coating. The TiO2-ZrO2 sol-gel coatings were sintered at 300 and 500 °C. SEM analysis shows that sintering at 300 °C produces a uniform, slightly dense structure without micro-cracks, while sintering at 500 °C results in a denser structure with micro-cracks due to higher stress and shrinkage. EDS confirms that sintering temperature affects the elemental composition of the coating, with higher temperatures causing the volatilization or diffusion of Ti and Zr. Roughness measurements indicate that the Ra value increases with the sintering temperature, meeting dental application requirements. Electrochemical measurements by open-circuit potential, EIS, and cyclic potentiodynamic curves demonstrate that sintering temperature and saliva composition affect corrosion resistance, with NaF and mouthwashes (Listerine Total Care Teeth Protection® and Meridol®) generally increasing charge transfer resistance and double-layer capacitance. The ceramic TiO2-ZrO2 coatings significantly reduce pitting corrosion susceptibility at physiological and acidic pH, with the 500 °C sintered coating showing better protective properties. These findings highlight the potential of TiO2-ZrO2 coatings in enhancing the performance of Co-Cr-Mo dental alloys.

Bimetallic FeCo metal–organic framework based cascade reaction system: Enhanced peroxidase activity for antibacterial performance

Metal-organic frameworks (MOFs), as a peroxidase (POD), can catalyze the conversion of H2O2 to reactive oxygen species (ROS) for antibacterial application. To achieve strong antibacterial activity, it is necessary to improve the enzyme-like activity of MOFs. In this study, FexCoMOF was synthesized by incorporating Co(II) to improve the electron transfer of Fe(III)/Fe(II), which enhanced its redox capacity as a nanozyme and further promoted the generation of hydroxyl radical (⋅OH), exhibiting higher POD activity. Doping with different amounts of Co(II) altered the particle size, specific surface area, and surface defects of FexCoMOF, thus exhibiting differential enzyme-like activities. Additionally, a glucose-responsive enzyme cascade reaction system based on Fe4CoMOF/glucose oxidase (GOx) was established. In the presence of glucose, the in situ-generated substrate H2O2 was in contact with the catalytic site and the generated gluconic acid enabled Fe4CoMOF to maintain maximum enzyme activity under physiological pH conditions, avoiding damage caused by the use of exogenous high concentrations of H2O2. In the in vitro antibacterial experiment, the minimum inhibitory concentration (MIC) of Fe4CoMOF/GOx was 10 μg mL−1 for Escherichia coli (E. coli) and 5 μg mL−1 for Staphylococcus aureus (S. aureus) (∼108 CFU mL−1). The increase in enzyme activity resulted in a considerable reduction in the dose of the antibacterial agent, which was conducive to improving bio-safety. The in vivo experiment in mice demonstrated that the glucose-responsive Fe4CoMOF-based cascade reaction system had excellent antibacterial properties and remarkably promoted wound healing. The antibacterial agent based on bimetallic MOF developed in this work provides a new idea for cascade catalytic antibacterial therapy and will have remarkable application prospects in biomaterials and nanomedicine.

Fluorescence imaging of dopamine in living cells triggered by unique coupling reactions

BackgroundDopamine (DA) is a significant neurotransmitter and catecholamine molecule in the mammalian brain. It plays a crucial role in perception, cognition, central nervous system regulation, and hormone secretion. The detection of DA levels in living systems is a vital aspect of the research and early diagnosis of neurological disorders. ResultsIn this study, we achieved an effective fluorescence generation specific to DA under physiological pH conditions by coupling the DA detection reaction to the HClO oxidation reaction. This method has been used for the detection of DA in cells, as well as for the visualization of DA levels in cellular models of inflammation and depression. SignificanceThis is the first time that utilizes an organic fluorescent molecular probe to detect DA in living cells.

Detection of carboxylesterases by an activatable NIR fluorescence probe with high selectivity in living systems

Carboxylesterases (CEs) have attracted increasingly attention in the physiological and pathological processes of many diseases such as diabetes, hepatocellular carcinoma (HCC) and drug metabolism. Selective detection of CEs activity is imperative to evaluate the pathophysiological process of CEs-related disease. Herein, a selective near-infrared (NIR) fluorescent probe (DCM-CE) with high selectivity is reported. DCM-CE was composed of dicyanoisophorone-based fluorophore and carbamate unit which is a highly selective identification group for CEs. DCM-CE exhibited good sensitivity for CEs detection at physiological pH and temperature. Furthermore, DCM-CE featured large Stokes shift (175 nm) and good at tracking the drug-induced trace change of CEs activity in HepG2 cells with little effect on cell viability. Moreover, DCM-CE was applied to monitor the activity of CEs in living mice. Taken all together, DCM-CE had extensive potential application value in detecting CEs for evaluating related diseases.