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Graphical abstract Highlights • An enzyme-free H 2 O 2 amperometric sensor is developed. • Pd nanoparticles supported on sulfonic acid functionalized mesoporous silica microspheres (Pd@SO 3 H-MSM) is employed. • Pd@SO 3 H-MSM is used for real-time detection of H 2 O 2 released from living tumor cells and healthy normal cells. • Pd@SO 3 H-MSM exhibits no toxicity to living cells. Abstract An enzyme-free sensitive hydrogen peroxide (H 2 O 2) amperometric sensor is developed to detect H 2 O 2 released from living cells using palladium nanoparticles supported on sulfonic acid functionalized mesoporous silica microspheres (Pd@SO 3 H-MSM). It is synthesized by an easy and facile method and is subsequently used for fabrication of an electrochemical sensing scaffold via drop-casting modification of a glassy carbon electrode (represented as GC/Pd@SO 3 H-MSM). Comprehensive characterizations including transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis spectrophotometry and electrochemical impedance spectroscopy to confirm the existence and nature of Pd nanoparticles in Pd@SO 3 H-MSM. GC/Pd@SO 3 H-MSM electrode demonstrates electrocatalytic activity for H 2 O 2 reduction in phosphate buffer, leading to a sensitive H 2 O 2 amperometric sensor with wide linear range (47.0 nM-1.0 mM), low detection limit (14.0 nM) and high sensitivity (0.36 μA mM−1 cm-2). It exhibits high selectivity, good reproducibility and long-term stability. More importantly, Pd@SO 3 H-MSM exhibits no toxicity to living cells and based on its remarkable analytical advantages, it is further unswervingly used to execute real-time detection of H 2 O 2 released from living tumor cells and healthy normal cells. Thus Pd@SO 3 H-MSM acts as promising material for amperometric determination of H 2 O 2 as well as used to accomplish real-time quantitative detection of H 2 O 2 in biological environment. [ABSTRACT FROM AUTHOR]

Plants possess an efficient, two-tiered immune system to combat pathogens and pests. Several decades of research have characterized different features of these two well-known tiers, PTI and ETI (Pattern/ Effector-triggered Immunity). NLR (Nucleotide-binding domain Leucine-rich Repeat) receptors have been found to link PTI to ETI, and be required for full potentiation of plant immune responses in several systems. Intra-cellular helper-NLRs (h-NLRs) mediate ETI and have been focused on extensively in recent research. Previously, we investigated the roles of the h-NLR SlNRC4a in tomato immunity, finding that a specific mutation in this gene results in gain of function constitutive defense activation and broad disease resistance. Deletion of the entire NRC4 clade, which contains 3 genes, can compromise tomato immunity. Here, we decided to investigate the role of an additional clade member, SlNRC4b , in basal immunity. We generated a gain of function mutant in SlNRC4b using CRISPR-Cas9, as well as a double gain of function mutant in both genes. Similarly to the slnrc4a mutant, a slnrc4b mutant also possessed increased basal immunity and broad spectrum disease resistance. The double mutant displayed additive effects in some cases, with significant increases in resistance to fungal phytopathogens as compared with each of the single mutants. Our work confirms that the NRC4 family h-NLRs are important in the plant immune system, suggesting that this gene family has the potential to be promising in targeted agricultural adaptation in the Solanaceae family, promoting disease resistance and prevention of yield loss to pathogens. • h-NLR receptors mediate ETI and link ETI to PTI within the plant immune system. • A gain of function mutation in the h-NLR SlNRC4a activates defense constitutively. Here, we investigated the role of SlNRC4b in basal immunity. • A slnrc4b mutant possessed increased basal immunity and disease resistance. • The double slnrc4a/b mutant displayed additive effects. • The NRC4 family shows promise for targeted agricultural adaptation for disease resistance. [ABSTRACT FROM AUTHOR]

Microbial interference plays an imperative role in plant development and response to various stresses. However, its involvement in mitigation of oxidative stress generated by plant parasitic nematode in plants remains elusive. In the present investigation, the efficacy of microbe’s viz. , Chitiniphilus sp. MTN22 and Streptomyces sp. MTN14 single and in combinations was examined to mitigate oxidative stress generated by M. incognita in medicinal plant, Bacopa monnieri . Microbial combination with and without pathogen also enhanced the growth parameters along with secondary metabolites (bacoside) of B. monnieri than the pathogen inoculated control. The study showed that initially the production of hydrogen peroxide (H 2 O 2 ) was higher in dual microbes infected with pathogen which further declined over M. incognita inoculated control plants. Superoxide dismutase and free radical scavenging activity were also highest in the same treatment which was linearly related with least lipid peroxidation and root gall formation in B. monnieri under the biotic stress. Microscopic visualization of total reactive oxygen species (ROS), H 2 O 2 , superoxide radical and programmed cell death in host plant further extended our knowledge and corroborated well with the above findings. Furthermore, scanning electron microscopy confirmed good microbial colonization on the host root surface around nematode penetration sites in plants treated with dual microbes under pathogenic stress. The findings offer novel insight into the mechanism adopted by the synergistic microbial strains in mitigating oxidative stress and simultaneously stimulating bacoside production under pathogenic stress. [ABSTRACT FROM AUTHOR]

In this report, an electrochemical sensing scaffold (ESS) for hydrazine (HZ) and nitrobenzene (NB) have been developed based on gold nanoparticles decorated mesoporous silica microspheres (Au-MSM) modified glassy carbon (GC) electrode (represented as GC/Au-MSM). The presence and formation of gold nanoparticles in Au-MSM composite material is verified by X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy and by electrochemical methods. The textural and thermal properties are studied by nitrogen adsorption-desorption and thermogravimetric analysis, respectively. The electrocatalytic sensing behavior of GC/Au-MSM towards HZ and NB are investigated in detail employing various electrochemical techniques. Amperometry measurements as a function of HZ concentration exhibit two linear calibration ranges of 5.0 μM to 0.5 mM and 0.5–18.0 mM. Similarly, the differential pulse voltammetry measurements as a function of NB concentration show a linear calibration range of 0.1 μM to 2.5 mM. The limit of detection is evaluated to be 0.11 μM and 15.0 nM for HZ and NB, respectively. The kinetic parameters for HZ oxidation and NB reduction are discussed using chronoamperometry. The proposed GC/Au-MSM ESS shows good selectivity over potent interferences and applied to determine HZ and NB in various water samples. [ABSTRACT FROM AUTHOR]

This work reports the individual as well as simultaneous determination of ascorbic acid (AA) and uric acid (UA) by glassy carbon electrode (GCE) modified with a nanocomposite film of gold nanoparticles (Au NPs) inclusively adhered to MCM-41 type mesoporous silica spheres (Au-MSS). The impregnation of Au NPs into mesoporous silica spheres (MSS) is well established by surface characterization and electrochemical techniques. The Au-MSS modified GCE (GCE/Au-MSS) exhibits stable redox peaks, characteristics of Au NPs. Further, GCE/Au-MSS shows effective electrocatalytic oxidation of both AA and UA diminishing the overpotentials by 580 and 405 mV, respectively, than at bare GCE. Similarly, GCE/Au-MSS diminishes the oxidation overpotentials of AA and UA by 200 and 210 mV, respectively, relative to GCE/MSS. Differential pulse voltammetry technique is employed for the simultaneous determination of AA and UA in the presence of one another. The limit of detection is found to be 1.65 μM and 2.14 μM for AA and UA, respectively. The kinetic parameters like diffusion coefficient and the catalytic rate constant for the AA and UA electro-oxidations have been computed using chronoamperometric techniques. High sensitivity is displayed by the modified electrode and has been successfully employed for the analysis of UA in human blood serum. [ABSTRACT FROM AUTHOR]

Plant hormones act as chemical messengers, transducing cellular and organ-level cues, executing plant growth, development, reproduction, metabolism, and response to environmental stress. In addition to the production of hormones by plants, fungi can also produce compounds that are similar to phytohormones, and may modulate growth, physiology, and immunity in both plants and fungi. The "classical" plant growth hormone, cytokinin (CK) is known to have roles in plant-fungi interactions. In plants, CKs are involved in various processes including plant growth and development, seed germination, apical dominance, balance between shoot and root tissue, leaf senescence, and plant-pathogen-interactions. We recently reported that CK can also affect fungal development. CK is not produced solely by plants, as can be synthesized by plant-associated microorganisms such as bacteria and fungi. Fungal phytopathogens may also activate plant CK signalling/sensing via secretion of effector molecules. Fungal CKs secreted by (hemi)biotrophic pathogens can serve as virulence factors, however, most necrotrophic fungal plant pathogens have not been reported to secrete CKs during plant infection. Though a lifestyle-dependent role for CK signalling/perception was suggested for fungal plant pathogens, little is known about CK perception, sensing, and signalling in fungal organisms. In this review, we focus on the production of fungal CKs and their role in development and virulence, as well as the possibilities for CK perception and signalling in the fungal kingdom, where CHASE-domain containing proteins are largely absent. [ABSTRACT FROM AUTHOR]

Highlights: [•] An electrochemical sensing platform based on new anion exchange polymer is constructed. [•] Ion exchange voltammetry and electrocatalysis are used for ascorbic acid (AA) determination. [•] Kinetic parameters of electrocatalytic oxidation of AA are evaluated. [•] Low detection limit with moderate sensitivity is achieved for AA determination. [Copyright &y& Elsevier]

[Display omitted] • Chikungunya is an arboviral disease caused by chikungunya virus (CHIKV) infection. • Till date no treatment is available for chikungunya. • Andrographolide (Andro) is a major bioactive compound of plant Andrographis paniculata. • Andro inhibits CHIKV multiplication and symptoms associated with chikungunya. Andrographolide, the major bioactive compound of the plant Andrographis paniculata , exerts anti-inflammatory, cyto-, neuro- and hepato-protective effects. Traditional remedies for infectious diseases include A. paniculata for maladies like fever, pain, rashes which are associated with chikungunya and other arboviral diseases. Since andrographolide and A. paniculata have potent antiviral properties, the present review aims to provide a comprehensive report of symptoms and immunological molecules involved in chikungunya virus (CHIKV) infection and the therapeutic role of andrographolide in the mitigation of chikungunya and associated symptoms. Studies on the therapeutic role of A. paniculata and andrographolide in chikungunya and other viral infections published between 1991 and 2021 were searched on various databases. The havoc created by chikungunya is due to the associated debilitating symptoms including arthralgia and myalgia which sometimes remains for years. The authors reviewed and summarized the various symptoms and immunological molecules related to CHIKV replication and associated inflammation, oxidative and unfolded protein stress, apoptosis and arthritis. Additionally, the authors suggested andrographolide as a remedy for chikungunya and other arboviral infections by highlighting its role in the regulation of molecules involved in unfolded protein response pathway, immunomodulation, inflammation, virus multiplication, oxidative stress, apoptosis and arthritis. The present review demonstrated the major complications associated with chikungunya and the role of andrographolide in alleviating the chikungunya associated symptoms to encourage further investigations using this promising compound towards early development of an anti-CHIKV drug. Chemical Compound studied: andrographolide (PubChem CID: 5318517) [ABSTRACT FROM AUTHOR]

Development of cost-effective, durable, and efficient bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is still required for efficient fuel cells, metal-air-batteries, and water electrolysis. For that purpose we have prepared tetrakis(3′,5′-dimethoxyphenyl)porphyrinato cobalt(II) (CoDMTPP) and 5,10,15,20-tetrakis(3′,5′-dihydroxyphenyl)porphyrinato cobalt(II) (CoDHTPP). Further, multi-walled carbon nanotubes (MWCNTs) based composites of CoDMTPP (MWCNTs-CoDMTPP) and CoDHTPP (MWCNTs-CoDHTPP) are also prepared and characterized through spectroscopy (UV–vis, FTIR, and XPS), microscopy (SEM, TEM with EDAX), X-ray diffraction, thermogravimetry, and electrochemical techniques. The materials, MWCNTs-CoDMTPP and MWCNTs-CoDHTPP are immobilized on glassy carbon (GC) electrodes, represented as GC/MWCNTs-CoDMTPP and GC/MWCNTs-CoDHTPP. They show efficient ORR activity in acidic, basic, and neutral (pH 7.0 buffer) mediums. Further, both of these electrodes exhibit significant OER activity in 0.1 M KOH, indicating the bifunctional activity in basic medium. Based on the kinetic studies, the presence of –OH in the CoDHTPP is found to enhance the ORR activity. The electrodes, GC/MWCNTs-CoDMTPP and GC/MWCNTs-CoDHTPP exhibit high methanol tolerance capacity. A very small change in onset potential of 12 mV at GC/MWCNTs-CoDMTPP and 3 mV at GC/MWCNTs-CoDHTPP electrodes are observed for the ORR after 3000 continuous potential cycles indicating the high operational stability of the modified electrodes. Image 1 • MWCNTs-CoDMTPP and MWCNTs-CoDHTPP composites were prepared and characterized. • They show efficient ORR and OER activities with high operational stability. • Thus, they act as bifunctional electrocatalysts. • They could be promising alternatives to replace Pt and Ir based electrocatalysts. • The –OH group present in the CoDHTPP is found to enhance the ORR activity. [ABSTRACT FROM AUTHOR]

Two homologous series of mesogenic Schiff-bases, N -4-((alkoxy)-(phenyl-3-hydroxy-4-(4-(5-methylbenzimidazol))-2-alkoxysalicylaldimine)benzoate ( 7a–d ) and N -4′-(5-methyl-benzimidazole)-phenyl-4-alkoxysalicylaldimine ( 8a–d ) incorporating benzimidazole moiety have been prepared and the molecular structures studied by FT-IR, NMR and ESI-MS spectrometry. Mesogenic behaviour was investigated by polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and variable temperature powder X-ray diffraction (PXRD) techniques. Changing the spacer (ester-linked to non-ester linked) of the Schiff-base results in enhancement of thermal stability and phase transition temperature. The members of series-I show monotropic SmA while those of series-II reflect enantiotropic SmA mesomorphism. An electrochemical study of a representative Schiff base in each series ( 7d and 8c ) showed an electrical band gap 1.26 eV and 1.22 eV respectively. [ABSTRACT FROM AUTHOR]

Classical Metal-Organic Frameworks (MOFs), although able to accumulate chemicals from solution, are usually electrochemically “inactive”. Here, it is demonstrated for the zinc-containing MOF-5(Zn) (and MOF-5W(Zn)) system, that silver incorporation (Ag@MOF-5(Zn), prepared via a solvothermal process) can be used to assist/promote release and electrochemical oxidation of accumulated nitrophenols (2-methyl-4-nitrophenol, 4-nitrophenol, and 2-nitrophenol). Nitrophenols belong to a group of compounds that are present in diesel exhaust and considered harmful pollutants. The enhanced electrochemical detection of nitrophenols at a glassy carbon electrode modified with Ag@MOF-5(Zn) is suggested to be due to analyte accumulation with estimated Langmuirian binding constants of 40 × 10 3 M −1 (for 2-methyl-4-nitrophenol and 4-nitrophenol) and 15 × 10 3 M −1 (for 2-nitrophenol) and electrochemical detection/conversion with a current enhancement of more than one order of magnitude due to potential driven release from Ag@MOF-5(Zn). Surface characterization and electrochemical techniques suggest that silver is present in Ag@MOF-5(Zn) in metallic form and probably also embedded into the framework. This silver incorporation changes the electrochemical oxidation behavior towards nitrophenols in MOF-5(Zn) from “inactive” to “active”. The new class of metal@MOF materials is highlighted as practical nano-composites. [ABSTRACT FROM AUTHOR]

An electrochemical sensing platform which comprises gold nanoparticles (Au NPs) incorporated zinc based metal-organic framework (MOF-5) is developed for the sensitive determination of nitrite and nitrobenzene. MOF-5 and Au NPs incorporated MOF-5 (Au-MOF-5) are synthesized and characterized by UV-vis absorption, powder X-ray diffraction, FT-IR, scanning electron microscopy with energy dispersive X-ray analysis and elemental mapping, transmission electron microscopy and atomic force microscopy. Oxidation of nitrite is effectively electrocatalyzed at Au-MOF-5 with significant increase in oxidation current (41 and 38% in comparison with bare glassy carbon (GC) and MOF-5 coated GC (GC/MOF-5) electrodes, respectively) and with considerable decrease in the oxidation potential (0. 17 and 0.25 V in comparison with bare GC and GC/MOF-5 electrodes, respectively). The electrocatalytic reduction of nitrobenzene at GC/Au-MOF-5 is confirmed by an appreciable increase in the reduction current (79 and 36% in comparison with bare GC and GC/MOF-5 electrodes, respectively) and a small shift in the reduction potential (20 mV in comparison with GC/MOF-5). The detection limit is calculated as 1.0 μM with a sensitivity of 0.23 μAμM −1 cm −2 for nitrite and 15.3 μM with a sensitivity of 0.43 μAμM −1 cm −2 for nitrobenzene determinations. The Au-MOF-5 based electrochemical sensing platform shows high stability and selectivity even in the presence of several interferences (including phenols, inorganic ions and biologically important molecules) with a broad calibration range. Certain kinetic parameters of nitrite oxidation and nitrobenzene reduction have also been studied by hydrodynamic voltammetry. [ABSTRACT FROM AUTHOR]