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The rational construction of efficient and low-cost electrocatalysts for the hydrogen evolution reaction (HER) is critical to seawater electrolysis. Herein, trimetallic heterostructured core-shell nanoboxes based on Prussian blue analogues (Ni-Co@Fe-Co PBA) were synthesized using an iterative coprecipitation strategy. The same coprecipitation procedure was used for the preparation of the PBA core and shell, with the synthesis of the shell involving chemical etching during the introduction of ferrous ions. Due to its unique structure and composition, the optimized trimetallic Ni-Co@Fe-Co PBA possesses more active interfacial sites and a high specific surface area. As a result, the developed Ni-Co@Fe-Co PBA electrocatalyst exhibits remarkable electrocatalytic HER performance with small overpotentials of 43 and 183 mV to drive a current density of 10 mA cm-2 in alkaline freshwater and simulated seawater, respectively. Operando Raman spectroscopy demonstrates the evolution of Co2+ from Co3+ in the catalyst during HER. Density functional theory simulations reveal that the H*-N adsorption sites lower the barrier energy of the rate-limiting step, and the introduced Fe species improve the electron mobility of Ni-Co@Fe-Co PBA. The charge transfer at the core-shell interface leads to the generation of H* intermediates, thereby enhancing the HER activity. By pairing this HER catalyst (Ni-Co@Fe-Co PBA) with another core-shell PBA OER catalyst (NiCo@A-NiCo-PBA-AA) reported by our group, the fabricated two-electrode electrolyzer was found to achieve high output current densities of 44 and 30 mA cm-2 at a low voltage of 1.6 V in alkaline freshwater and simulated seawater, respectively, exhibiting remarkable durability over a 100 h test.

Lattice-strained Bi2S3 with 3D hierarchical structures are prepared through a top-down route by a topotactic transformation. High-resolution transmission electron microscopy and X-ray diffraction (XRD) confirm the lattice spacing is expanded by prolonged sulfuration. Performance studies demonstrate that Bi2S3 with the largest lattice expansion (Bi2S3-9.7%, where 9.7% represents the lattice expansion) exhibits a greater electrocatalytic hydrogen evolution reaction (HER) activity compared to Bi2S3 and Bi2S3-3.2%. Density functional theory calculations reveal the expansion of the lattice spacing reduces the bandwidth and upshifts the band center of the Bi 3d orbits, facilitating electron exchange with the S 2p orbits. The resultant intrinsic electronic configuration exhibits favorable H* adsorption kinetics and a reduced energy barrier for water dissociation in hydrogen evolution. Operando Raman and post-mortem characterizations using XRD and X-ray photoelectron spectroscopy reveal the generation of pseudo-amorphous Bi at the edge of Bi2S3 nanorods of the sample with lattice strain during HER, yielding Bi2S3-9.7%-A. It is worth noting when Bi2S3-9.7%-A is assembled as a positive electrode in an asymmetric supercapacitor, its performance is greatly superior to that of the same device formed using pristine Bi2S3-9.7%. The as-prepared Bi2S3-9.7%-A//activated carbon asymmetric supercapacitor achieves a high specific capacitance of 307.4 F g−1 at 1 A g−1, exhibiting high retention of 84.1% after 10 000 cycles.

Limited knowledge exists on the virulence factors of Candida tropicalis and the mechanisms of azole resistance that lead to an intensified pathogenicity and treatment failure. We aimed to evaluate the virulence factors and molecular mechanisms of azole resistance among C. tropicalis isolated from patients with candidemia. Several virulence factors, including extracellular enzymatic activities, cell surface hydrophobicity (CSH), and biofilm formation, were evaluated. Antifungal susceptibility pattern and expression level of ERG11, UPC2, MDR1, and CDR1 genes of eight (4 fluconazole resistance and 4 fluconazole susceptible) clinical C. tropicalis isolates were assessed. The correlation between the virulence factors and antifungal susceptibility patterns was analyzed. During a 4 year study, forty-five C. tropicalis isolates were recovered from candidemia patients. The isolates expressed different frequencies of virulence determinants as follows: coagulase 4 (8.9%), phospholipase 5 (11.1%), proteinase 31 (68.9%), esterase 43 (95.6%), hemolysin 44 (97.8%), biofilm formation 45 (100%) and CSH 45(100%). All the isolates were susceptible to amphotericin B and showed the highest resistance to voriconazole. There was a significant positive correlation between micafungin minimum inhibitory concentrations (MICs) and hemolysin production (rs = 0.316). However, we found a negative correlation between fluconazole MICs and esterase production (rs = −0.383). We observed the high expression of ERG11 and UPC2 genes in fluconazole-resistant C. tropicalis isolates. C. tropicalis isolated from candidemia patients extensively displayed capacities for biofilm formation, hemolysis, esterase activity, and hydrophobicity. In addition, the overexpression of ERG11 and UPC2 genes was considered one of the possible mechanisms of azole resistance.

Since its verification in just 2019, there have been numerous high-profile papers reporting improved efficiency of the lithium-mediated electrochemical nitrogen reduction system to make ammonia. However, the literature lacks a cohesive investigation systematically linking bulk electrolyte properties to electrochemical performance and Solid Electrolyte Interphase (SEI) properties. In this study, we vary electrolyte salt concentration and observe a transition from an unstable working electrode potential to working electrode potential stability and peak in Faradaic efficiency of 7.8 ± 0.5 % at 0.6 M LiClO4. The behaviour is linked to the formation of Solvent Separated Ion Pairs in the electrolyte through Raman spectroscopy. Time of Flight Secondary Ion Mass Spectrometry and X-Ray Photoelectron Spectroscopy reveal a more inorganic, and therefore more stable, SEI layer with increasing salt concentration. A drop in Faradaic efficiency is seen at concentrations higher than 0.6 M LiClO4, which is attributed to a combination of a loss in nitrogen solubility and diffusivity as well as increased SEI conductivity as measured by Electrochemical Impedance Spectroscopy.

Despite their ubiquitous usage and increasing societal dependence on Li-ion batteries, there remains a lack of detailed empirical evidence of Li intercalation/deintercalation into graphite even though this process dictates the performance, longevity, and safety of the system. Here, we report direct detection and dissociation of specific crystallographic phases in the lithiated graphite, which form through a stepwise staging process. Using operando measurements, LiC18, LiC12, and LiC6 phases are observed via distinct low-frequency Raman features, which are the result of displacement of the graphite lattice by induced local strain. Density functional theory calculations confirm the nature of the Raman-active vibrational modes, to the layer breathing modes (LBMs) of the lithiated graphite. The new findings indicate graphene-like characteristics in the lithiated graphite under the deep charged condition due to the imposed strain by the inserted Li. Moreover, our approach also provides a simple experimental tool to measure induced strain in the graphite structure under full intercalation conditions.

Single-atom catalysts, in particular the Fe-N-C family of materials, have emerged as a promising alternative to platinum group metals in fuel cells as catalysts for the oxygen reduction reaction. Numerous theoretical studies have suggested that dual atom catalysts can appreciably accelerate catalytic reactions; nevertheless, the synthesis of these materials is highly challenging owing to metal atom clustering and aggregation into nanoparticles during high temperature synthesis treatment. In this work, dual metal atom catalysts are prepared by controlled post synthetic metal-coordination in a C

The lithium-mediated method of electrochemical nitrogen reduction, pioneered by Tsuneto et al1 then verified by Andersen et al2, is currently the sole paradigm capable of unequivocal electrochemical ammonia synthesis. Such a system could allow the production of green, distributed ammonia for use as fertiliser or a carbon-free fuel. However, despite great improvements in Faradaic efficiency and stability since just 20193, fundamental understanding of the mechanisms governing nitrogen reduction and other parasitic reactions is lacking. Lithium Ion Battery (LIB) research can provide insight; since both lithium-mediated electrochemical ammonia synthesis and LIBs utilise an organic solvent and lithium salt, both form a Solid Electrolyte Interphase (SEI), which is electronically insulating but ionically conducting, at the electrode surface. In LIBs, this is necessary to stabilize and cycle low potential materials4. In lithium-mediated ammonia synthesis, the SEI could also have a critical role in controlling the access of protons and other key reactants to the catalytically active sites and promoting greater selectivity toward nitrogen reduction to ammonia5. While some characterisation of the SEI has been carried out for the lithium-mediated nitrogen reduction system6, the literature still lacks holistic studies which aim to carefully characterise the bulk electrolyte and SEI components and link them to system performance. In this work we use insight from battery science to tackle a significant stability problem in lithium-mediated nitrogen reduction. The traditional electrolyte employed by Tsuneto et al. was 0.2 M LiClO4 in a 99:1 tetrahydrofuran to ethanol mix. While this system can produce ammonia, the working electrode potential becomes more negative over time. Our initial investigations show that this problem stems from an unstable SEI which becomes increasingly organic. Simply by raising the concentration of LiClO4 in the electrolyte, we vastly improve stability, as shown in figure 1(a), and boost Faradaic efficiency. Bulk electrolyte salt solvation properties are investigated through Raman spectroscopy, as shown in figure 1(b). Here we observe the emergence of a shoulder at around 930 cm-1 with increasing LiClO4 concentration, which we assign to the emergence of Contact-Ion-Pairs (CIPs) through comparison to Density Functional Theory calculations. These CIPs mean that perchlorate anion degradation products are more abundant in the formed SEI, as shown in our X-Ray Photoelectron Spectroscopy and Time-of-Flight Secondary Ion Mass spectrometry results. This more inorganic SEI protects the electrolyte against further degradation, preventing the working electrode drift to more negative potentials. We then link this behaviour to a peak observed in the Faradaic efficiency of ammonia synthesis at 0.6 M LiClO4 by also considering decreasing N2 solubility and diffusivity, as well as a more ionically conductive SEI, in an increasingly concentrated electrolyte. We also present never-before seen cross-sectional images of the SEI using cryogenic Focussed Ion Beam milling and Scanning Electron Microscopy, further aiding understanding of how salt solvation affects the morphology of the formed SEI and system performance. Our results emphasise the need to consider SEI properties in electrolyte design for lithium-mediated nitrogen reduction, as well as the need to balance desirable SEI properties with desirable bulk electrolyte properties. Tsuneto, A., Kudo, A. & Sakata, T. Efficient Electrochemical Reduction of N 2 to NH 3 Catalyzed by Lithium . Chemistry Letters vol. 22 851–854 (1993). Andersen, S. Z. et al. A rigorous electrochemical ammonia synthesis protocol with quantitative isotope measurements. Nature 570, 504–508 (2019). Westhead, O., Jervis, R. & Stephens, I. E. L. Is lithium the key for nitrogen electroreduction? Science. 372, 1149–1150 (2021). Peled, E. & Menkin, S. Review—SEI: Past, Present and Future. J. Electrochem. Soc. 164, A1703–A1719 (2017). Singh, A. R. et al. Electrochemical Ammonia Synthesis—The Selectivity Challenge. ACS Catal. 7, 706–709 (2017). Li, K. et al. Enhancement of lithium-mediated ammonia synthesis by addition of oxygen. Science. 1597, 1593–1597 (2021). Figure 1

Prostate Specific Antigen (PSA) is a biomarker employed for detection of prostate cancer. An electrochemical nanobiosensor is designed and fabricated using a molecularly imprinted polymer for the simple and fast PSA detection. The imprinted polymer served as a PSA artificial receptor fabricated by electrochemical polymerization of pyrrole on screen-printed gold electrode in the presence of PSA. PSA was a molecular template for the polymer. The fabricated nanobiosensor was evaluated by differential pulse voltammetry and using K3[Fe(CN)6]/K4[Fe(CN)6] as an electrochemical marker. The factors influencing the performance of the sensor including electropolymerization cycle umbers (to control the thickness of the polymer film) and time of PSA binding were optimized to attain the best sensitivity. The binding affinity of the nanobiosensor surface was examined by the Freundlich isotherm with Freundlich constant and exponent of 0.89 ng mL−1 and 10.93, respectively. The nanobiosensor demonstrated a fast rebinding rate and a high capacity of PSA recognition with detection limit of 2.0 pg mL−1.

Background Virulence factors intensify the pathogenicity of Candida species in candidemia. Limited knowledge exists regarding the azole-resistant mechanism and virulence factors of Candida tropicalis. Consequently, we aimed to evaluate the virulence factors and the molecular mechanisms of azole resistance among C. tropicalis isolated from bloodstream infection. Materials and methods Forty-five C. tropicalis isolates recovered from candidemia patients were evaluated for virulence factors, including extracellular enzymatic activities, cell surface hydrophobicity (CHS), and biofilm formation. Antifungal susceptibility pattern and expression level of ERG11, UPC2, MDR1, and CDR1 genes of eight azole resistance C. tropicalis isolates were assessed. Results The isolates expressed different frequencies of virulence determinants as follows: coagulase 4 (8.9%), phospholipase 4 (8.9 %), proteinase 31 (68.9 %), CSH 43 (95.6 %), esterase 43 (95.6 %), hemolysin 44 (97.8%), and biofilm formation 45 (100%). All the isolates were susceptible to amphotericin B and showed the highest resistance to voriconazole. The high expression of ERG11 and UPC2 genes in fluconazole-resistant C. tropicalis isolates were observed. Conclusion C. tropicalis isolated from candidemia patients extensively displayed capacities for biofilm formation, hemolysis, esterase activity, and hydrophobicity. In addition, the overexpression of ERG11 and UPC2 genes can be considered as one of the possible mechanisms of azole resistance.

Biofilm formation by Candida species is an influential virulence factor in candidemia pathogenesis. We investigated the relationship between biofilm formation of Candida tropicalis isolates with the clinical characteristics and mortality outcomes in patients with candidemia.Thirty-nine C. tropicalis isolates were recovered from patients with candidemia admitted to two university hospitals in Tehran, Iran. Biofilm mass and metabolic activity of C. tropicalis biofilms were assessed in vitro with two colorimetric methods. The sessile minimum inhibitory concentrations (SMICs) were evaluated in vitro by treating preformed biofilms with diluted concentrations of azoles according to CLSI-M27 A3/S4 protocol, followed by metabolic activity quantification. The expressions of ERG11, UPC2, MDR1, and CDR1 genes were also evaluated.All C. tropicalis isolates produced biofilm. Respectively, higher7-day and ≥7-day mortality rates were found among cases with high metabolic activity (46.7% vs. 13%, P = 0.03) and high biofilm mass (31.8% vs. 0, P = 0.029). Sessile cells had high resistance to fluconazole, voriconazole, and itraconazole. The azole minimum inhibitory concentrations (MICs) of C. tropicalis sessile were significantly greater than the planktonic minimum inhibitory concentrations (PMICs). In fluconazole-treated biofilms, the expression of ERG11 and UPC2 genes was increased.Our findings highlight the importance of C. tropicalis biofilm formation as an important factor in candidemia pathogenesis and the clinical outcome of patients with candidemia.

CO 2 electroreduction offers a route to net-zero-emission production of C 2H 4—the most-produced organic compound. However, the formation of carbonate in this process causes loss of CO 2 and a severe energy consumption/production penalty. Dividing the CO 2-to-C 2H 4 process into two cascading steps—CO 2 reduction to CO in a solid-oxide electrolysis cell (SOEC) and CO reduction to C 2H 4 in a membrane electrode assembly (MEA) electrolyser—would enable carbonate-free C 2H 4 electroproduction. However, this cascade approach requires CO-to-C 2H 4 with energy efficiency well beyond demonstrations to date. Here, we present a layered catalyst structure composed of a metallic Cu, N-tolyl-tetrahydro-bipyridine, and SSC ionomer that enables efficient CO-to-C 2H 4 in a MEA electrolyser. In the full SOEC-MEA cascade approach, we achieve CO 2-to-C 2H 4 with no loss of CO 2 to carbonate and a total energy requirement of ~138 GJ (ton C 2H 4) −1, representing a ~48% reduction in energy intensity compared with the direct route.

The widespread bacteria, parasites and viruses are considered as the potential sources of infections which can endanger the public health. Accordingly, sensitive, rapid and cost-effective analysis methods are required for identification of the pathogens to achieve an improved quality of life. Trichomonas vaginalis is among the commonly colonizing parasite which threatens human health by causing Trichomoniasis infection. In the present study, we demonstrate the fabrication and application of a novel electrochemical genosensor based on an electrodeposited gold nanostructure as a transducer combined with toluidine blue (TB) as a redox marker. A specific DNA sequence was immobilized on the transducer and the hybridization process was detected using differential pulse voltammetry. The genosensor showed excellent performance towards detection of TV with high sensitivity and good selectivity. A linear correlation was obtained between the electrochemical response of the genosensor with a complementary-sequence DNA concentration in the range of 1.0 × 10−19 to 1.0 × 10−12 mol L−1 with a limit of detection as low as 3.1 × 10−20 mol L−1. Moreover, the prepared genosensor could discriminate between the complementary-sequence, base-mismatched-sequences and a non-complementary-sequence oligonucleotides via TB binding. Comparison of the actual human samples analyzed by both the prepared genosensor and the standard gel electrophoresis confirmed the practical applicability of the genosensor.

Sodium–oxygen (Na–O2) batteries exhibit a low charging overpotential owing to the reversible formation and decomposition of sodium superoxide (NaO2) on discharge and charge cycles. However, the cycling performance of the battery system is compromised by the side reactions occurring between the reactive NaO2 discharge product with the other components of the cell including the air electrode and the organic electrolyte. In the present study, we employ a Raman imaging technique to reveal the chemical mechanism behind the decomposition reaction of NaO2 in the presence of diglyme-based electrolyte. Our results illustrate the formation of oxalate-based side products resulting from prolonged exposure of NaO2 to the cell electrolyte. Moreover, we show that Na2O2·2H2O is not the thermodynamically favorable side product for decomposition of NaO2 and may only be formed under the high-energy beam used by the measuring probe. The findings of this study help to better understand the underlying chemical reaction mechani...

Despite the impressive progress in the development of sodium-air batteries for energy storage, the current sodium-air batteries are still far from practical application in electric vehicles. A proposed sodium-air battery was successfully constructed using a NASICON structured solid electrolyte and a liquid anode, which demonstrated low voltage gap, reversibility, and high safety. The liquid anode was fabricated by dissolving sodium metal into a mixed solution of biphenyl and ethers. Due to the fantastic conductivity of the liquid anode, the battery exhibits a high discharge voltage of 2.88 V and a low voltage gap of 0.14 V at a current density of 0.1 mA cm−2, which leads to a high round trip efficiency of 95.3%. In addition, due to the high ionic conductivity of the liquid anode and low interfacial resistance between the liquid anode and solid electrolyte, the battery demonstrated a power density of 39 mW cm−2, the highest value to date for alkaline metal-air batteries. Furthermore, the battery exhibited good cycling performance, and no significant degradation in energy efficiency was observed during the whole charge-discharge process. More importantly, no strong reaction was observed between the liquid anode and water, which significantly improved the safety of the battery. The highly conductive liquid anode can be extended to other sodium-based batteries. Therefore, this work provides an avenue for exploring new types of highly safe liquid anode batteries, which is a potential candidate for next-generation energy storage technology.

Low-cost, high-energy-density, and highly efficient devices for energy storage have long been desired in our society. Herein, a novel high-energy-density hybrid sodium–air cell was fabricated successfully on the basis of acidic catholytes. Such a hybrid sodium–air cell possess a high theoretical voltage of 3.94 V, capacity of 1121 mAh g–1, and energy density of 4418 Wh kg–1. First, the buffering effect of an acidic solution was demonstrated, which provides relatively long and stable cell discharge behaviors. Second, the catholytes of hybrid sodium–air cells were optimized systematically from the solutions of 0.1 M H3PO4 + 0.1 M Na2SO4 to 0.1 M HAc + 0.1 M NaAc and it was found that the cells with 0.1 M H3PO4 + 0.1 M Na2SO4 displayed a maximum power density of 34.9 mW cm–2. The cell with 0.1 M H3PO4 + 0.1 M Na2SO4 displayed higher discharge capacity of 896 mAh g–1. Moreover, the fabricated acidic hybrid sodium–air cells exhibited stable cycling performance in ambient air and they delivered a low voltage ga...

Releasing greenhouse gases into the atmosphere because of widespread use of fossil fuels by humankind has resulted in raising the earth's temperature during the past few decades. Known as global warming, increasing the earth's temperature may in turn endanger civilization on the earth by starting a cycle of environmental changes including climate change and sea level rise. Therefore, replacing fossil fuels with more sustainable energy resources has been considered as one of the main strategies to tackle the global warming crisis. In this regard, energy saving devices are required to store the energy from sustainable resources like wind and solar when they are available and deliver them on demand. Moreover, developing plug-in electric vehicles (PEVs) as an alternative for internal combustion engines has been extensively pursued, since a major sector of fossil fuels is used for transportation purposes. However, currently available battery systems fail to meet the required demands for energy storage. Alkali metal-O

Sodium–air batteries are attracting increasing research interest due to their high theoretical energy density and environmentally benign characteristics. Although sodium–air batteries share a similar concept, design, and composition when compared with their lithium–air counterparts, they still show many differences in their electrochemical behaviors and mechanisms. In the present work, the employment of four different types of polymers as binders in air electrodes for sodium–air batteries is presented, while the electrochemical and physical characterizations are carried out. Insights into how polymer binders impact the reaction mechanisms and formation of superoxide/peroxide species of sodium–air batteries from the view of their functional groups are revealed.

Developing high energy density batteries, such as metal–air systems, requires a good understanding of their underlying electrochemical principles. In situ characterization methods provide valuable insight into the discharge/charge mechanism of Na–O2 cells. However, previous application of soft X-ray absorption spectroscopy has been limited to ex situ studies on the discharge products of the cell. Here we report an in situ soft X-ray absorption technique for Na–O2 cells to study the formation and decomposition of the discharge products during battery cycling. Taking advantage of the elemental selectivity and chemical sensitivity of soft X-ray absorption spectroscopy, we reveal the instability of discharge products in the Na–O2 cell environment. Our results illustrate that in situ soft X-ray absorption spectroscopy is an efficient probe to study the electrochemical mechanism of alkali metal–O2 energy storage systems.

Recently, convergence of nanotechnology, medicine, biology and chemistry has provided novel solutions for efficient diagnosis systems for disease markers. A detection method of troponin I (TnI), as the gold standard of acute myocardial infarction biomarker, was investigated and a novel aptasensor was presented for this biomarker. An array of gold nanodumbbells was firstly synthesized using putrescine as the shape directing agent at a surface. It was then applied as a transducer for the immobilization of a 76-mer TnI aptamer to fabricate a simple electrochemical TnI aptasensor. Using the aptasensor, TnI was detected in a linear range of 0.05–500 ng mL −1 with a limit of detection of 8.0 pg mL −1 . The aptasensor showed a diagnostic sensitivity of 100% and a diagnostic specificity of 85% when challenged with blood serum samples of 89 individuals.

Sodium–oxygen batteries have received a significant amount of research attention as a low-overpotential alternative to lithium–oxygen. However, the critical factors governing the composition and morphology of the discharge products in Na–O2 cells are not thoroughly understood. Here we show that oxygen containing functional groups at the air electrode surface have a substantial role in the electrochemical reaction mechanisms in Na–O2 cells. Our results show that the presence of functional groups at the air–electrode surface conducts the growth mechanism of discharge products toward a surface-mediated mechanism, forming a conformal film of products at the electrode surface. In addition, oxygen reduction reaction at hydrophilic surfaces more likely passes through a peroxide pathway, which results in the formation of peroxide-based discharge products. Moreover, in-line X-ray diffraction combined with solid state 23Na NMR results indicate the instability of discharge products against carbonaceous electrodes. T...

23Na MAS NMR spectra of sodium–oxygen (Na–O2) cathodes reveals a combination of degradation species: newly observed sodium fluoride (NaF) and the expected sodium carbonate (Na2CO3), as well as the desired reaction product sodium peroxide (Na2O2). The initial reaction product, sodium superoxide (NaO2), is not present in a measurable quantity in the 23Na NMR spectra of the cycled electrodes. The reactivity of solid NaO2 is probed further, and NaF is found to be formed through a reaction between the electrochemically generated NaO2 and the electrode binder, polyvinylidene fluoride (PVDF). The instability of cell components in the presence of desired electrochemical reaction products is clearly problematic and bears further investigation.

Solid state catalysts play a critical role in peroxide alkali metal–O2 cells. However, the underlying mechanism behind the catalytic activity remains controversial due to the different nature of oxygen reduction and evolutions reactions (ORR, OER) in non-aqueous cells compared to those in classic aqueous based reactions. In the present study, we reveal a detailed spectroscopic and electrochemical picture of the mechanism of catalytic activity in Na– and Li–O2 cells. We demonstrate that ORR and OER catalytic activity in alkali metal–O2 cells primarily originates from the stabilization of O2− intermediates on the catalyst surface during the electrochemical reaction. Monitoring the electronic state of the solid state catalyst during the ORR and OER revealed a dynamic interaction occurring between the catalyst and the discharge product. The morphology and composition of discharge products is also illustrated to be influenced by solid state catalysts. The findings of the present study suggest that catalysts with a higher oxygen-bonding capability may exhibit a higher catalytic activity in alkali metal–O2 cells.

Background: Alzheimer’s disease (AD) is a common form of dementia, characterized by production and deposition of β-amyloid peptide in the brain. Thus, β-amyloid peptide is a potentially promising biomarker used to diagnose and monitor the progression of AD. Objective: The study aims to develop a biosensor based on a molecularly imprinted poly-pyrrole for detection of β-amyloid. Material and Methods: In this experimental study, an imprinted poly-pyrrole was employed as an artificial receptor synthesized by electro-polymerization of pyrrole on screen-printed carbon electrodes in the presence of β-amyloid. β-amyloid acts as a molecular template within the polymer. The biosensor was evaluated by cyclic voltammetry using ferro/ferricyanide marker. The parameters influencing the biosensor performance, including electro-polymerization cycle umbers and β-amyloid binding time were optimized to achieve the best biosensor sensitivity. Results: The β-amyloid binding affinity with the biosensor surface was evaluated by the Freundlich isotherm, and Freundlich constant and exponent were obtained as 0.22 ng mL-1 and 10.60, respectively. The biosensor demonstrated a detection limit of 1.2 pg mL-1. The biosensor was applied for β-amyloid determination in artificial cerebrospinal fluid. Conclusion: The biosensor is applicable for early Alzheimer’s disease detection.

1 , respectively. The combination of caffeine with FLU showed stronger antifungal activity against C. albicans PTCC5027. The addition of 12.5mgL -1 caffeine to FLU 10-50 mgL -1 (below MIC90) inhibited the growth of C. albicans PTCC5027 by 99.3%-99.7%, the concentrations at which neither caffeine nor FLU alone affected the growth. Conclusion: It can be concluded that caffeine has antifungal effect on C. albicans and in combination with FLU can enhance the antifungal activity of FLU against C. albicans . The synergism of the combination of caffeine and FLU induces multiple antifungal effects, resulting in the use of lower doses of the FLU. It suggests that this can decrease the side effects of antifungal drugs.

Objective The effect of candidemia on immunologic parameters in breast tumor bearing patients is not well studied. Here, we hypothesised that candidemia in the tumor background may change the outcome of immunologic parameters and tumor condition. Method Mice were divided into four groups, including normal, tumor, Candida infected (only Candidiasis) and tumor/Candidiasis groups. Tumor changes were recorded daily after tumor transplantation and induction of candidemia. Splenocytes of mice were harvested, cultured, and stimulated with PHA; afterwards, IL-4, IL-10, IFN-γ, TNF-α and TGF-β cytokines were assessed using ELISA kits. We also evaluated the population of CD4+CD25+Foxp3+ regulatory T cells in the tumor infiltrated and splenocytes. Results The results showed that infection with C. albicans decreased the IFN-γ/IL-4 ratio in tumor/candidiasis and candidiasis groups versus their non-infected controls. IL-10, TGF-β and TNF-α levels increased in the candidiasis group. In addition, Candidemia led to an increase in the Treg population in tumor microenvironment and splenocytes of experimental groups compared with non-infected controls. Finally, candidemia increased tumor growth of tumor/Candidiasis group compared with the tumor group. Conclusion It seems that systemic infection with C. albicans could not only induce regulatory T cells but also result in dysregulation of cytokine network and thereby facilitate tumor growth.

Background: The importance of Candida albicans as the most common cause of fungal infections in humans is undeniable. Genotyping methods have been developed as useful tools to differentiate between fungal strains isolated from various infections. Several molecular typing methods have been described for C. albicans, and fragment length analysis of microsatellites called microsatellite fragment length polymorphism (MLP) is one of the most accurate genotyping methods. Objectives: The present study aimed at evaluating the genetic diversity and genetic relationships among C. albicans isolates recovered from HIV-positive patients with oral candidiasis in Iran using MLP. Methods: We analyzed 30 isolates of C. albicans obtained from HIV-positive patients in Tehran. Genotypes of C. albicans isolates associated with oropharyngeal candidiasis were determined using microsatellite length polymorphism analysis. Three loci including EF3, CDC3, and HIS3 were amplified using multiplex PCR. After amplification, the product was run on an automated single-capillary genetic analyzer, and band sizes (known as alleles) were calculated with gene scan mapper. Results: PCR MLP typing of the 30 isolates under study yielded 27 different profiles, and the discriminatory power index was obtained as 0.993. Ten alleles and 18 different combinations were detected for the EF3 gene, 7 alleles and 18 combinations for the EF3 gene, and 10 alleles and 14 combinations for the HIS3 gene. Only 2 isolates were homozygous in all the 3 loci. To identify the origin of superficial infections in 6 patients, C. albicans isolates from the superficial as well as oral samples were simultaneously genotyped. Results showed the identity of genotypes in 4 of these patients. For 1 patient, the C. albicans genotype of the nails was different from the genotype observed in the oral cavity, which raised the possibility of an exogenous source for the superficial infection. Also, there were changes at only 1 or 2 alleles, which represented microevolution in some isolates. Conclusions: The high variation of genotypes throughout the population of C. albicans suggested that the microsatellite fragment length polymorphism using multiplex PCR-based system provided high-speed genotyping, indicating its usefulness in molecular epidemiological evaluation.

Bacteria, parasites and viruses are found widely in the environment as potential pathogens, and can be the source of infections. Therefore, sensitive and rapid methods for identification of the pathogens are required to achieve a better quality of life. Enterococcus faecalis commonly colonizes and threatens human health. In the present study, we demonstrate the fabrication of a novel electrochemical DNA biosensor based on electrodeposited gold nanostructures as a transducer substrate combined with toluidine blue (TB) as a redox marker. Binding of TB with the single and double stranded DNA (ssDNA and dsDNA) was shortly investigated, and based on the results, TB could discriminate between ssDNA and dsDNA. A specific thiolated ssDNA sequence was immobilized on the transducer substrate, and DNA hybridization was followed by differential pulse voltammetry. The DNA biosensor showed excellent performances with high sensitivity and good selectivity. The DNA biosensor was applied to detect a synthetic target in a linear range of 1.0 × 10−17–1.0 × 10−10 mol L−1 with a limit of detection (LOD) of 4.7 × 10−20 mol L−1. In addition, LOD of the DNA biosensor for the detection of genomic DNA was found to be 30.1 ng μL−1.

Secreted aspartyl proteinases (Saps), are gene products that have been shown to directly contribute to Candida albicans pathogenicity. Despite the clear difficulties of systemic C. albicans infections control, Antimicrobial peptides (AMPs) are regarded as one of the most promising alternatives in this regard. Recently, drug-loaded electrospun nanofibers have attracted a great deal of attention. In this study we have established the nanofibrous scaffold of new synthetic peptide/Poly (Vinyl Alcohol)/Poly l-Lactic Acid on expression of Secretory aspartyl proteinases 4 to 6 genes of C. albicans in comparison with free peptide. We designed new synthetic Antimicrobial peptide (AMPs) used bioinformatics tools to predict structure and stabilities. The electrospinning method was used to produce the polymeric nanofibers. Scanning Electron Microscopy (SEM) was used to measure the nanofibers diameters and morphology. To analyze the expression of SAP4, SAP5 and SAP6 genes, RNA was extracted from clinical isolates of C. albicans before and after treatment with subinhibitory concentrations of new synthetic peptide on nanofibrous scaffold of new synthetic peptide/PVA/PLLA and then the cDNA was synthesized and used for Real-time PCR assay. Scanning electron microscopy (SEM) images showed that the morphology, the diameter, are affected from peptide. Reletive quantitative Real-time PCR results revealed that the mRNA levels of SAP4, SAP5 and SAP6 genes significantly decreased after treatment with nanofibrous scaffold of new synthetic peptide/PVA/PLLA (P .05). Electrospun nanofibrous of new Synthetic Peptide/PVA/PLLA is effective in downregulating of expression SAP4, SAP5 and SAP6 genes of C. albicans strains.

Detecting and monitoring the pathogens with high selectivity and sensitivity is critical for public health. In the present study, we demonstrated a specific analytical strategy for sensitive detection of Leishmania infantum genome. The developed sensor utilized toluidine blue as a hybridization indicator and a Leishmania infantum-specific capture DNA sequence immobilized on a high-surface area gold nanostructure as an electrochemical transducer. The produced analytical response was based on the hybridization of the single-stranded DNA from the target with the immobilized DNA sequence at the electrode surface. The developed DNA sensor in this study was successfully employed to detect a synthetic Leishmania infantum target sequence in a wide concentration range from 1 × 10−18 to 1 × 10−10 mol L−1 with a detection limit of 0.2 amol L−1 with the ability to discriminate the target sequence from mismatched sequences. Moreover, the designed DNA sensor showed a good reproducibility and stability during repeated regeneration and hybridization cycles. The DNA sensor could detect Leishmania infantum genome in a wide concentration range from 15 to 50 ng μL−1 with a detection limit of 29 ng μL−1. Furthermore, clinical trials confirmed the applicability of the developed DNA sensor for practical applications.

Room temperature sodium–air batteries have a similar design and concept as lithium–air batteries. Using ambient air instead of pure oxygen as oxygen source is challenging because the minor components in air could lead to various side reactions and influence the electrochemical reaction route. Although water is an innegligible component in air, its impact on Li– and Na–air batteries is often underestimated. In this study, the electrochemical behavior of Na–air batteries under different relative humidity (RH) has been systemically investigated by galvanic cycling and cyclic voltammetry tests, as well as the identification of corresponding discharge products by physical characterizations such as XRD, FT-IR, and SEM. The reaction mechanisms of Na–air batteries under humid conditions are revealed and discussed. Na–air batteries suffer from more severe impact from the water content in air than Li–air batteries. NaOH and its derivatives are found to form and are proven to be fatal to the cells under humid ambien...

A binder-free three-dimensional (3D) nanostructured air electrode composed of vertically grown nitrogen doped carbon nanotubes on carbon paper (NCNT-CP) is developed and applied to Na–O2 cells. The 3D architecture of the air electrode results in increased discharge capacity by optimizing the utilized area of the electrode material. The chemical and electrochemical reaction mechanisms of the cell are also explored with the use of synchrotron-based X-ray absorption spectroscopy (XAS). Investigation of the discharge product of Na–O2 cells during discharge and charge cycles using X-ray absorption near-edge structure (XANES) indicates that both sodium superoxide and peroxide are produced under various physicochemical conditions and can be subsequently decomposed with different overpotentials. Furthermore, formation of carbonate-based parasitic products is also shown to restrict the cyclability of the cell.

Self-stacked nitrogen-doped carbon nanotubes (NCNTs) and pristine carbon nanotubes (CNTs) on commercial porous polypropylene substrates have been applied as air electrodes for sodium-air batteries (SAB). Both NCNT and CNT air electrodes exhibit highly reversible electrochemical activities and large capacities under low current densities in SABs, while NCNT electrodes show much higher rate performance and extended cycling life under high current densities. The superior electrochemical behavior of NCNT electrodes is attributed to the robust network of aligned NCNTs, which enables rapid oxygen and liquid electrolyte transport while accommodating the volume change originating from discharge product aggregation during cycling. Moreover, uniform coverage of the discharge product has been observed on the NCNT air electrodes, in contrast to the random and discrete dispersion of discharge product on the CNT air electrodes. The unique morphologies and growth mechanism of discharge products on NCNT electrodes are believed to be due to the outstanding catalytic activity of the nitrogen-doped sites in the NCNTs, which play a critical role in the high cycling stability of NCNT air electrodes for SABs.

Two-dimensional (2D) ultrathin nanocrystals represent a family of emerging nanomaterials with many proposed applications; however, the interlayer re-stacking between sheets greatly decreases the performance during practical operation. This work demonstrates a facile strategy to solve this challenging problem by rational assembly of 2D nanocrystals into three-dimensional (3D) aerogels, which paves the way for harvesting excellent structural properties of both nanostructures and macrostructures. The resultant 3D MnO2 aerogel shows significantly increased discharge capacity in Li–air batteries in comparison to its powder-like counterpart (4581.4 vs. 3902.6 mA h g−1), which outperforms many MnO2 and other transition metal-based electrocatalysts. Meanwhile, the as-fabricated Li–air cell demonstrates good rate capability and cycle life. Further mechanism study reveals that the improved performance is associated with ultrathin MnO2 nanosheets which allow highly exposed catalytic centres, as well as its excellent aerogel structure with rich porosity and a 3D continuous network that maximizes the utilization of MnO2 species for catalytic reactions. This study may open up new opportunities for making full use of 2D nanocrystals for a number of energy storage/conversion techniques.

Background: Candida albicans is the most common pathogen in patients with vulvovaginitis. Secretory aspartyl proteinases (SAPs) are potential factors in the virulence of C. albicans. Antimicrobial peptides (AMPs) are recognized as a promising antimicrobial group of drugs with a membrane degradation mechanism. Occurrence of resistance to these drugs is quite rare. The impact of rapid membrane degradation on AMPs is relative to the prevention or delay in drug resistance mechanisms in different microbes. Objectives: The purpose of this study was to compare the inhibitory effects of the designed NK95 peptide and caspofungin on expression of SAP4-SAP6 genes from clinical vaginal isolates of C. albicans . Methods: In this experimental study, samples were collected from 350 women, who were suspected of vulvovaginal candidiasis and were referred to Zahedan gynecology clinics during 6 months. The clinical specimens were cultured in Sabouraud glucose agar (SGA). Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to identify the vaginal isolates of C. albicans. Afterwards, the NK95 peptide was designed and synthesized. Drug susceptibility test was carried out at different concentrations of NK95 peptide and caspofungin. RNA extraction, cDNA synthesis, and quantitative Real-time PCR were performed on the clinical isolates before and after treatment with the designed peptide and caspofungin. Results: Based on the findings of this study, the minimum inhibitory concentration (MIC90), MIC50, and minimum fungicidal concentration (MFC) of C. albicans isolates were 62.5, 31.25, and 125 μg/mL for the designed peptide, respectively. The SAP4 (45%), SAP5 (85%), and SAP6 (73%) genes expressions significantly reduced at 48 hours after treatment with the designed peptide (P < 0.05). Conclusions: Our findings showed that the designed NK95 peptide has antifungal effects on the clinical vaginal isolates of C. albicans. Moreover, it has potential down-regulating on expression of SAP4, SAP5 and SAP6 genes.

Sodium-oxygen batteries have received a significant amount of research attention as a low-overpotential alternative to lithium-oxygen. However, the critical factors governing the composition and morphology of the discharge products in Na-O

Meso/macroporous cobalt (II) oxide nanoflakes were electrodeposited in a one-step process in the presence of N -methylpyrrolidone. On the surface of nanoflakes, a specific single stranded DNA sequence from the genome of influenza A subtype was then immobilized to fabricate an electrochemical biosensor. Hybridization of the biosensor with complementary, non-complementary and base-mismatch sequences was electrochemically detected. The biosensor was also employed to detect complementary DNA of viral RNA in culture and human samples. The biosensor could detect the complementary sequence with a detection limit of 86.4 amol L −1 and a linear concentration range of 1.0 fmol L −1 to 1.0 nmol L −1 . It also detected a complementary DNA sequence converted from viral RNA with a detection limit of 0.28 ng μL −1 in a linear concentration range of 0.5–10 ng μL −1 . Low detection limit, simple method of preparation of the transducer and no needing any DNA strand modification and tag are the principal advantages of the biosensor.