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The present research deals with the development of a novel bioinspired in situ fabrication of reduced graphene oxide (rGO)-silver nanoparticle (AgNPs) nanocomposite (rGO@AgNCs) using microbes namely Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA). The fabricated rGO@AgNCs were characterized using Ultraviolet-visible (UV-Vis) spectroscopy, Fourier-transform infrared spectroscopy (FTIR), particle size analysis, polydispersity index (PDI), zeta potential analysis, energy dispersive x-ray analysis (EDAX), Raman spectroscopy, powder x-ray diffraction (PXRD), high-resolution transmission electron microscopy (HR-TEM) analysis, etc. Furthermore, the rGO@AgNCs-PA and rGO@AgNCs-SA interaction with serum protein, pH stability study, and in vitro dissolution of AgNPs were also performed. The research findings of the proposed study demonstrated the simultaneous reduction of graphene oxide (GO) and AgNPs and the formation of rGO@AgNCs in the presence of microbes. The in vitro dissolution studies of rGO@AgNCs composites showed better AgNPs dissolution with controlled release and offered remarkable matrix integrity throughout the dissolution period. The size and stability of rGO@AgNCs-PA and rGO@AgNCs-SA had no significant changes at physiological pH 7.4. A minimal decrease in the zeta potential of rGO@AgNCs was observed, which may be due to the weak interaction of nanocomposites and albumin. The antibacterial application of the synthesized nanocomposite was evaluated against a pathogenic mastitis-forming bacterium. The obtained results suggested an admirable antibacterial activity of synthesized nanocomposites against the tested microbes. This knowledge will assist the scientific fraternity in designing novel antibacterial agents with enhanced antibacterial activity against various veterinary pathogens in near future., (© 2022 IOP Publishing Ltd.)

Chemodynamic therapy (CDT), deemed as a cutting-edge antineoplastic therapeutic tactics, efficaciously suppresses tumors via catalytically yielding hydroxyl radicals ( • OH) in tumor regions. Nevertheless, its biomedical applications are often restricted by the limited hydrogen peroxide (H 2 O 2 ) level and upregulated antioxidant defense. Herein, a versatile nanoreactor is elaborately designed via integrating Cu 2- x S and MnO 2 for T 1 -weighted magnetic resonance (MR) imaging-guided CDT, synergistically enhanced through hypothermal ablation and oxidation resistance reduction, thereby displaying splendid antitumor efficiency as well as suppression on pulmonary metastasis. The as-synthesized Cu 2- x S@MnO 2 nanoreactors afford acid-dependent Cu-based and glutathione (GSH)-activated Mn-based catalytic properties for bimodal CDT. Owing to excellent absorbance at the second near-infrared (NIR-II) window, the Cu 2- x S furnishes hypo-photo-thermal therapy (PTT) against tumor growth and ameliorates the catalytic performance for thermal-enhanced CDT. Additionally, MnO 2 significantly downregulates GSH and glutathione peroxidase 4, which synergistically boosts CDT via promoting oxidative stress, simultaneously generating Mn 2+ for MR contrast improvement and activatable tumor imaging. Therefore, this study proffers a new attempt centered on the collaborative strategy integrating NIR-II hypothermal PTT and synergistically enhanced CDT for tumor eradication.

Microbial contamination is one of the major dreadful problems that raises hospitalization, morbidity and mortality rates globally, which subsequently obstructs socio-economic progress. The continuous misuse and overutilization of antibiotics participate mainly in the emergence of microbial resistance. To circumvent such a multidrug-resistance phenomenon, well-defined nanocomposite structures have recently been employed. In the current study, a facile, novel and cost-effective approach was applied to synthesize Ag@Ag 2 O core-shell nanocomposites (NCs) via chemical method. Several techniques were used to determine the structural, morphological, and optical characteristics of the as-prepared NCs. XRD, Raman, FTIR, XPS and SAED analysis revealed a crystalline hybrid structure of Ag core and Ag 2 O shell. Besides, SEM and HRTEM micrographs depicted spherical nanoparticles with size range of 19-60 nm. Additionally, zeta potential and fluorescence spectra illustrated aggregated nature of Ag@Ag 2 O NCs by - 5.34 mV with fluorescence emission peak at 498 nm. Ag@Ag 2 O NCs exhibited higher antimicrobial, antibiofilm, and algicidal activity in dose-dependent behavior. Interestingly, a remarkable mycocidal potency by 50 μg of Ag@Ag 2 O NCs against Candida albican; implying promising activity against COVID-19 white fungal post-infections. Through assessing cytotoxicity, Ag@Ag 2 O NCs exhibited higher safety against Vero cells than bulk silver nitrate by more than 100-fold., (© 2021. The Author(s).)

Growing evidence across organisms points to altered energy metabolism as an adverse outcome of metal oxide nanomaterial toxicity, with a mechanism of toxicity potentially related to the redox chemistry of processes involved in energy production. Despite this evidence, the significance of this mechanism has gone unrecognized in nanotoxicology due to the field's focus on oxidative stress as a universal─but nonspecific─nanotoxicity mechanism. To further explore metabolic impacts, we determined lithium cobalt oxide's (LCO's) effects on these pathways in the model organism Daphnia magna through global gene-expression analysis using RNA-Seq and untargeted metabolomics by direct-injection mass spectrometry. Our results show that a sublethal 1 mg/L 48 h exposure of D. magna to LCO nanosheets causes significant impacts on metabolic pathways versus untreated controls, while exposure to ions released over 48 h does not. Specifically, transcriptomic analysis using DAVID indicated significant enrichment (Benjamini-adjusted p ≤0.0.5) in LCO-exposed animals for changes in pathways involved in the cellular response to starvation (25 genes), mitochondrial function (70 genes), ATP-binding (70 genes), oxidative phosphorylation (53 genes), NADH dehydrogenase activity (12 genes), and protein biosynthesis (40 genes). Metabolomic analysis using MetaboAnalyst indicated significant enrichment (γ-adjusted p <0.1) for changes in amino acid metabolism (19 metabolites) and starch, sucrose, and galactose metabolism (7 metabolites). Overlap of significantly impacted pathways by RNA-Seq and metabolomics suggests amino acid breakdown and increased sugar import for energy production. Results indicate that LCO-exposed Daphnia respond to energy starvation by altering metabolic pathways, both at the gene expression and metabolite levels. These results support altered energy production as a sensitive nanotoxicity adverse outcome for LCO exposure and suggest negative impacts on energy metabolism as an important avenue for future studies of nanotoxicity, including for other biological systems and for metal oxide nanomaterials more broadly.

Leishmaniasis is a neglected disease that affects 12 million people living mainly in developing countries. Herein, 24 new N-oxide-containing compounds were synthesized followed by in vitro and in vivo evaluation of their antileishmanial activity. Compound 4f, a furoxan derivative, was particularly remarkable in this regard, with EC50 value of 3.6 μM against L. infantum amastigote forms and CC50 value superior to 500 μM against murine peritoneal macrophages. In vitro studies suggested that 4f may act by a dual effect, by releasing nitric oxide after biotransformation and by inhibiting cysteine protease CPB (IC50: 4.5 μM). In vivo studies using an acute model of infection showed that compound 4f at 7.7 mg/Kg reduced ~90% of parasite burden in the liver and spleen of L. infantum-infected BALB/c mice. Altogether, these outcomes highlight furoxan 4f as a promising compound for further evaluation as an antileishmanial agent., Competing Interests: The authors have declared that no competing interests exist.

A new approach for the preparation of (2-amino-3-cyano-4H-chromen-4-yl)phosphonate derivatives is described. The multicomponent reaction of salicylaldehydes, malononitrile and dialkyl phosphites catalyzed by pentamethyldiethylenetriamine (PMDTA) provided the bicyclic derivatives in high yields. The method developed did not require chromatographic separation, since the products could be recovered from the reaction mixture by simple filtration. Our approach made also possible condensation with secondary phosphine oxides, and this reaction has not been previously reported in the literature. The crystal structures of five derivatives were studied by single-crystal XRD analysis. The in vitro cytotoxicity on different cell lines and the antibacterial activity of the (2-amino-4H-chromen-4-yl)phosphonates synthesized were also explored. According to the IC 50 values determined, several derivatives showed moderate or promising activity against mouse fibroblast (NIH/3T3) and human promyelocytic leukemia (HL-60) cells. Furthermore, three (2-amino-3-cyano-4H-chromen-4-yl)phosphine oxides were active against selected Gram-positive bacteria.

Rationale: Sensitive and accurate imaging of cancer is essential for early diagnosis and appropriate treatment. For generally employed magnetic resonance imaging (MRI) in clinic, comprehending how to enhance the contrast effect of T 1 imaging is crucial for improving the sensitivity of cancer diagnosis. However, there is no study ever to reveal the clear mechanism of how to enhance the effect of T 1 imaging and accurate relationships of influencing factors. Herein, this study aims to figure out key factors that affect the sensitivity of T 1 contrast-enhanced MRI (CE-MRI), thereby to realize sensitive detection of tumors with low dose of CAs. Methods: Manganese oxide (MnO) nanoparticles (NPs) with various sizes and shapes were prepared by thermal decomposition. Factors impacting T 1 CE-MRI were investigated from geometric volume, surface area, crystal face to r 2 / r 1 ratio. T 1 CE-MR imaging of liver, hepatic and subcutaneous tumors were conducted with MnO NPs of different shapes. Results: The surface area and occupancy rate of manganese ions have positive impacts on the sensitivity of T 1 CE-MRI, while volume and r 2 / r 1 ratio have negative effects. MnO octahedrons have a high r 1 value of 20.07 mM -1 s -1 and exhibit an excellent enhanced effect in liver T 1 imaging. ZDS coating facilitates tumor accumulation and cellular uptake, hepatic and subcutaneous tumors could be detected with MnO octahedrons at an ultralow dose of 0.4 mg [Mn]/kg, about 1/10 of clinical dose. Conclusions: This work is the first quantitative study of key factors affecting the sensitivity of T 1 CE-MRI of MnO nanoparticles, which can serve as a guidance for rational design of high-performance positive MRI contrast agents. Moreover, these MnO octahedrons can detect hepatic and subcutaneous tumors with an ultralow dose, hold great potential for sensitive and accurate diagnosis of cancer with lower cost, less dosages and side effects in clinic., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Cobalt oxide nanoparticles (CoO NPs) were synthesized by the calcination method from the Co (II) complex which has the formula [Co(PVA)( P -ABA)(H 2 O) 3 ], PVA = polyvinyl alcohol, and P -ABA =  para -aminobenzoic acid. The calcination temperature was 550°C, and the products were characterized by element analysis, thermal analyses (TGA and DTA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV-Vis spectra, and scanning electron microscopy (SEM) techniques. The kinetic and thermodynamic parameters (∆H  ∗ , ∆G  ∗ , and ∆S  ∗ ) for the cobalt (II) complex are calculated. The charges been carried by the atoms cause dipole moment 10.53 and 3.84 debye and total energy 11.04 × 10 2 and 24.80 × 10 2 k Cal mol -1 for the Co (II) complex and cobalt oxide, respectively. X-ray diffraction confirmed that the resulting oxide was pure single-crystalline CoO nanoparticles. Scanning electron microscopy indicating that the crystallite size of cobalt oxide nanocrystals was in the range of 36-54 nm. Finally, the antimicrobial activity of cobalt oxide nanoparticles was evaluated using four bacterial strains and one fungal strain. Two strains of Gram-positive cocci ( Staphylococcus aureus and Enterococcus faecalis ), two strains of Gram-negative bacilli ( Escherichia coli and Pseudomonas aeruginosa ), and one strain of yeast such as fungi ( Candida albicans ) were used in this study., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2021 Maged S. Al-Fakeh and Roaa O. Alsaedi.)

Besides the pandemic caused by the coronavirus outbreak, many other pathogenic microbes also pose a devastating threat to human health, for instance, pathogenic bacteria. Due to the lack of broad-spectrum antibiotics, it is urgent to develop nonantibiotic strategies to fight bacteria. Herein, inspired by the localized "capture and killing" action of bacteriophages, a virus-like peroxidase-mimic (V-POD-M) is synthesized for efficient bacterial capture (mesoporous spiky structures) and synergistic catalytic sterilization (metal-organic-framework-derived catalytic core). Experimental and theoretical calculations show that the active compound, MoO 3 , can serve as a peroxo-complex-intermediate to reduce the free energy for catalyzing H 2 O 2 , which mainly benefits the generation of •OH radicals. The unique virus-like spikes endow the V-POD-M with fast bacterial capture and killing abilities (nearly 100% at 16 µg mL -1 ). Furthermore, the in vivo experiments show that V-POD-M possesses similar disinfection treatment and wound skin recovery efficiencies to vancomycin. It is suggested that this inexpensive, durable, and highly reactive oxygen species (ROS) catalytic active V-POD-M provides a promising broad-spectrum therapy for nonantibiotic disinfection., (© 2021 Wiley-VCH GmbH.)

Key Message: Ca 2+ NPs enhanced tolerance of Triticale callus under salt stress by improving biochemical activity and confocal laser scanning analysis, conferring salt tolerance on callus cells. CaO NPs (Ca 2+ ) are significant components that act as transducers in many adaptive and developmental processes in plants. In this study, effect of Ca 2+ NPs on the response and regulation of the protective system in Triticale callus under short and long-salt treatments was investigated. The activation of Ca 2+ NPs was induced by salt stress in callus of Triticale cultivars. MDA, H 2 O 2 , POD, and protein activities were determined in callus tissues. Concerning MDA, H 2 O 2 , protein activities, it was found that the Ca 2+ NPs treatment was significant, and it demonstrated a high correlation with the tolerance levels of cultivars. Tatlıcak cultivar was detected for better MDA activities in the short time with 1.5 ppm Ca 2+ NPs concentration of 50 g and 100 g NaCl. Similarly, the same cultivar responded with better H 2 O 2 activity at 1.5 ppm Ca 2+ NPs 100 g NaCl in the short time. POD activities exhibited a decreasing trend in response to the increasing concentrations of Ca 2+ NPs. The best result was observed at 1.5 ppm Ca 2+ NPs 100 g NaCl in the short term. Based on the protein content, treatment of short-term cultured callus cells with 1.5 ppm Ca 2+ NPs inhibited stress response and it significantly promoted Ca 2+ NPs signals as compared to control callus. Confocal laser scanning analysis proved that the application of Ca 2+ NPs could alleviate the adverse effects of salt stress by the inhibition of stress severity in callus cells. This study demonstrated, under in vitro conditions, that the application of Ca 2+ NPs can significantly suppress the adverse effects of salt stress on Triticale callus; it was also verified that the concentration of Ca 2+ NPs could be important parameter to be considered in adjusting the micronutrient content in the media for this plant.

In the present work, we report on the synthesis of crump-like nickel manganous oxide nanoparticles decorated partially reduced graphene oxide (NiMnO@pr-GO) nanocomposite through high-intensity ultrasonic bath sonication (ultrasonic frequency = 37 kHz and power = 150 W). The NiMnO@pr-GO nanocomposite modified glassy carbon electrode (GCE) was then employed for the electrochemical reduction of detrimental metronidazole (MNZ). The crystalline phase and formation of the NiMnO@pr-GO nanocomposites were confirmed by X-ray diffraction and other spectroscopic techniques. The cyclic voltammetry results demonstrate that this NiMnO@pr-GO nanocomposite modified GCE has a lower reduction potential and higher catalytic activity towards MNZ than do NiMnO and GO modified GCEs. Under optimized conditions, the fabricated NiMnO@pr-GO electrode can detect metronidazole over a wide linear range with a lower limit of detection of 90 nM. The sensitivity of the sensor was 1.22 µA µM -1 cm -2 and was found to have excellent selectivity and durability for the detection of MNZ., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In an effort to explore a new class of antidiabetic inhibitors, a new series of isoxazolidine and C-alkyl imine oxide derivatives scaffolds were designed, synthesized and fully characterized. The newly synthesized analogues were evaluated for their human pancreatic α-amylase (HPA) and human lysosomal acid-α-glucosidase (HLAG) inhibitory activities and have shown a higher potency than acarbose. The compounds 7b (23.1 ± 1.1 μM) and 7a (36.3 ± 1.6 μM) were identified as the potent HPA and HLAG inhibitors with inhibitory effect up to 9 and 21-fold higher than acarbose, respectively. Antihyperglycemic activity results were supported by molecular docking approach of the most potent compounds 7b and 7a showing stronger interactions with the active site of HPA and HLAG as well as by in silico absorption, distribution, metabolism, excretion and toxicity (ADMET) profile suggesting their satisfactory oral druglikeness without toxic effect. Therefore, it can be concluded that both 7b and 7a can be used as effective lead molecules for the development of HPA and HLAG inhibitors for the management of T2DM., (Copyright © 2020 Elsevier Inc. All rights reserved.)

With the growing interest of the medical industry in biocompatible nanoparticles (NPs), the current synthetic methods should be adapted to appropriate demands (toxicity, scalability, etc.). Most applications require colloidal systems to be stable not only in water but also in vivo, which represents a major challenge. In this study, biocompatible Ta2O5 NPs were synthesized by a solvothermal method avoiding toxic reagents, and surfactant-free stable hydrosols were obtained and used for computed tomography (CT) imaging. The small hydrodynamic size (2 nm) and colloidal stability of primary NPs were studied by dynamic light scattering (DLS). The particles were characterized by X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller analysis to confirm their structure and purity. To develop a stable hydrosol preparation protocol, the influence of pH and ultrasonication duration on the stability of Ta2O5 sols was analyzed by DLS and microelectrophoresis. To enhance the understanding of NP behavior in vivo, sol stability in conditions close to physiological (NaCl solutions) was studied in a pH range of 3-9. Hydrosols prepared by the proposed protocol were stable for at least 6 months and exhibited negligible cytotoxicity. Ta2O5 NPs also showed high CT contrast both in theoretical calculations and in vivo (rat gastrointestinal tract).

The exceptional nature of WO 3-x dots has inspired widespread interest, but it is still a significant challenge to synthesize high-quality WO 3-x dots without using unstable reactants, expensive equipment, and complex synthetic processes. Herein, the synthesis of ligand-free WO 3-x dots is reported that are highly dispersible and rich in oxygen vacancies by a simple but straightforward exfoliation of bulk WS 2 and a mild follow-up chemical conversion. Surprisingly, the WO 3-x dots emerged as co-reactants for the electrochemiluminescence (ECL) of Ru(bpy) 3 2+ with a comparable ECL efficiency to the well-known Ru(bpy) 3 2+ /tripropylamine (TPrA) system. Moreover, compared to TPrA, whose toxicity remains a critical issue of concern, the WO 3-x dots were ca. 300-fold less toxic. The potency of WO 3-x dots was further explored in the detection of circulating tumor cells (CTCs) with the most competitive limit of detection so far., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Double perovskites have been extensively studied in materials chemistry due to their excellent properties and novel features attributed to the coexistence of ferro/ferri/antiferro-magnetic ground state and semiconductor band gap within the same material. Double perovskites with Sr 2 NiMO 6 (M = Te, W) structure type have been synthesized using simple, non-toxic and costless aqueous citrate sol-gel route. The reaction yielded phase-pure nanocrystalline powders of two compounds: Sr 2 NiWO 6 (SNWO) and Sr 2 NiTeO 6 (SNTO). According to the Rietveld refinement of powder X-ray diffraction data at room temperature, Sr 2 NiWO 6 is tetragonal ( I 4/ m ) and Sr 2 NiTeO 6 is monoclinic ( C 12/ m 1), with average crystallite sizes of 49 and 77 nm, respectively. Structural studies have been additionally performed by Raman spectroscopy revealing optical phonons typical for vibrations of Te 6+ /W 6+ O 6 octahedra. Both SNTO and SNWO possess high values of dielectric constants (341 and 308, respectively) with low dielectric loss (0.06 for SNWO) at a frequency of 1 kHz. These values decrease exponentially with the increase of frequency to 1000 kHz, with the dielectric constant being around 260 for both compounds and dielectric loss being 0.01 for SNWO and 0.04 for SNTO. The Nyquist plot for both samples confirms the non-Debye type of relaxation behavior and the dominance of shorter-range movement of charge carriers. Magnetic studies of both compounds revealed antiferromagnetic behavior, with Néel temperature (T N ) being 57 K for SNWO and 35 K for SNTO.

Iron plays an important role in various physiological processes. However, the detailed biological functions of iron have not been sufficiently explored because of a lack of effective methods to monitoring iron, especially the labile ferrous ion (Fe 2+ ). In the current study, a novel turn-on phosphorescent probe for Fe 2+ quantification and visualization has been proposed based on the hybrid nanocomposite of manganese dioxide and gemini iridium complex (MnO 2 -GM-Ir). The surfactant-like GM-Ir with positive charges was beneficial to combine with the negatively charged manganese dioxide (MnO 2 ) nanosheets, and thus endowing the MnO 2 -GM-Ir nanocomposite excellent dispersion ability in the water as well as efficiently avoiding the interference to the detection caused by the agglomeration of nanocomposite. Phosphorescence of GM-Ir was effectively quenched by MnO 2 nanosheets through fluorescence resonance energy transfer (FRET) and the inner filter effect (IFE), while the phosphorescence could be significantly recovered in the presence of Fe 2+ via a selective Fe 2+ -mediated reduction of MnO 2 nanosheets, indicating a highly-specific selectivity towards Fe 2+ with a low detection limit (80 nM). The drug test assay and in vitro imaging studies further proved that the MnO 2 -GM-Ir nanocomposite could be employed as a promising probe for the quantitative detection of exogenous Fe 2+ in drug and in vitro imaging of living cells., Competing Interests: Declaration of competing interest There are no conflicts to declare., (Copyright © 2020. Published by Elsevier B.V.)

Natural or synthetic biomaterials are increasingly being used to support bone tissue repair or substitution. The combination of natural calcium phosphates with biocompatible alloys is an important route towards the development of new biomaterials with bioperformance and mechanical responses to mimic those of human bones. This article evaluated the structural, physical, mechanical and biological properties of a new mechanical improved nanocomposite elaborated by association of fish biphasic calcium phosphate (BCP) and niobium pentoxide (Nb 2 O 5 ). The nanocomposite (Nb-BCP) and the pure BCP, used as a positive control, were obtained by powder metallurgy. The density, porosity and microhardness were measured. The structural analysis was determined by X-ray diffraction (XRD) and the biological properties were studied in histological sections of critical size calvaria defects in rats, 7, 15, 30, 45 and 60 days after implantation of disks of both materials. Morphological description was made after scanning electron microscopy (SEM) and optical microscopy analysis. After sintering, the Nb-BCP nanocomposite presented four crystalline phases: 34.36% calcium niobate (CaNb 2 O 6 ), 21.68% phosphorus niobium oxide (PNb 9 O 25 ), 42.55% β-tricalcium phosphate (Ca 3 (PO 4 ) 2 ) and 1.31% of niobium pentoxide (Nb 2 O 5 ) and exhibited increases of 17% in density, 66% in Vickers microhardness and 180% in compressive strength compared to pure BCP. In vivo study, showed biocompatibility, bioactivity and osteoconductivity similar to pure BCP. SEM showed the formation of globular accretions over the implanted nanocomposites, representing one of the stages of bone mineralization. In conclusion, the BCP and Nb 2 O 5 formed a nanocomposite exhibiting characteristics that are desirable for a biomaterial, such as bioperformance, higher β-TCP percentage and improved physical and mechanical properties compared to pure BCP. These characteristics demonstrate the promise of this material for supporting bone regeneration.

In the current study, γ-AlOOH, γ-MnOOH, and α-Mn2O3 nanorods (NRs) were easily synthesized and applied as advanced antibacterial materials. γ-AlOOH NRs with 20 nm width, [100] crystal plane, and 200 nm length were fabricated through a surfactant-directed solvothermal method. γ-MnOOH NRs with 20 nm width, [101] crystal direction and 500 nm length were fabricated through a hydrothermal method. The prepared γ-MnOOH NRs were calcinated (for 5 h) at 700 °C to produce α-Mn2O3 NRs with 20 nm average width and increased surface area. The NRs' structures were confirmed through FT-IR, XRD, XPS, FESEM, and FETEM. The antibacterial activity of the NRs was studied against different Gram-negative and Gram-positive bacterial strains and yeast. The three NRs exhibited antibacterial activity against all of the used strains. Biological studies indicated that the NRs' antimicrobial activity increased in the order of γ-MnOOH < γ-AlOOH < α-Mn2O3 NRs. The α-Mn2O3 NRs exhibited the lowest MIC value (39 μg mL-1) against B. subtilis, B. pertussis, and P. aeruginosa. The prepared NRs exhibited a higher antimicrobial potential toward Gram-positive bacteria than Gram-negative bacteria. The higher antimicrobial activity of the α-Mn2O3 NRs is highlighted based on their larger surface area and smaller diameter. Consequently, uniform NR architectures, single crystallinity, small nanoscale diameters, and more highly exposed [110] Mn-polar surfaces outwards are promising structures for α-Mn2O3 antibacterial agents. These NRs adhered firmly to the bacterial cells causing cell wrapping and morphology disruption, and microbial death. The designed NRs provide a great platform for microbial growth inhibition.

We synthesized all major saturated and unsaturated 2-alkyl-4(1H)-quinolone N-oxides of Pseudomonas and Burkholderia, quantified their native production levels and characterized their antibiotic activities against competing Staphylococcus aureus. We demonstrate that quinolone core methylation and position of unsaturation in the alkyl-chain dictate antibiotic potency which supports the proposed mechanism of action.

Hypoxia within solid tumors severely limits the efficacy of photodynamic therapy (PDT). Biocompatible calcium peroxide nanoparticles (CaO2 NPs) have superior oxygen generating capacity for hypoxia relief but the relatively slow release of O2 from CaO2 NPs hampers the PDT efficacy enhancement. Herein, manganese dioxide (MnO2) is applied as a nanozyme to facilitate O2 release from CaO2 NPs. It is disclosed that the accelerated O2 release ensures a rapid and efficient amplification of the O2 level for an increased cytotoxic singlet oxygen production with chlorin e6 and leads to a down-regulated hypoxia-responsive protein expression, which eventually translates to a super-efficient PDT as evidenced by the complete eradication of mice bearing subcutaneous 4T1 tumors. Meanwhile, MnO2 imparts an MR T1 imaging modality for tumor detection and treatment planning. These findings signify the essential role of accelerated and efficient hypoxia relief in PDT efficacy enhancement and provide an effective paradigm to overcome hypoxia-associated resistance for an enhanced therapeutic efficacy.

Local surface plasmon resonance (LSPR)-enhanced catalysis has brought a substantial amount of opportunities across various disciplines such as photocatalysis, photodetection, and photothermal therapeutics. Plasmon-induced photothermal and hot carriers effects have also been utilized to activate the enzyme-like reactions. Compared with natural enzymes, the relatively low catalytic performance of nanozymes severely hampered the potential applications in the field of biomedicine. For these issues mentioned above, herein, we demonstrate a highly efficient sulfite oxidase (SuO x ) mimetic performance of plasmonic monolayer MoO x (ML-MoO x ) upon LSPR excitation. We also established that the considerable photothermal effect and the injection of hot carriers induced by LSPR are responsible for promoting the SuO x activity of ML-MoO x . The high transient local temperature on the surface of ML-MoO x generated by the photothermal effect facilitates to impact the reaction velocity and feed the SuO x -like activity, while the generation of hot carriers which are suggested as predominant effects catalyzes the oxidation of sulfite to sulfate through significantly decreasing the activation energy for the SuO x -like reaction. These investigations present a contribution to the basic understanding of plasmon-enhanced enzyme-like reaction and provided an insight into the optimization of the SuO x mimetic performance of nanomaterials.

In this work, a glutathione (GSH) sensing nano-platform using lucigenin as a fluorescent probe in the presence of MnO2 nanosheets was reported for the first time. Unlike the earlier fluorescent detection systems based on MnO2 nanosheets, which depend on Förster resonance energy transfer (FRET) or the dynamic quenching effect (DQE), the mechanism of the quenching process of MnO2 nanosheets on lucigenin fluorescence was attributed mainly to a static quenching effect (SQE) with a minor contribution of the inner filter effect (IFE). A double exponential fluorescence decay of lucigenin was obtained in various MnO2 nanosheet concentrations as a result of their SQE and IFE. Based on this phenomenon and taking advantage of the redox reaction between GSH and MnO2 nanosheets, we have developed a switch-on sensitive fluorescent method for GSH via the recovery of the MnO2 nanosheet-quenched fluorescence of lucigenin. A good linearity range of 1.0-150.0 μM with a low limit of detection (S/N = 3) of 180.0 nM was achieved, revealing the higher sensitivity for GSH determination in comparison with the previously reported MnO2 nanosheet-based turn-on fluorescent methods. The developed fluorescent nano-platform exhibits excellent selectivity with successful application for GSH detection in human serum plasma, indicating its good practicability for GSH sensing in biological and clinical applications.

Mass cytometry (MC) is a bioanalytical technique that uses metal-tagged antibodies (Abs) for high-dimensional single-cell immunoassays. Currently, this technology can measure over 40 parameters simultaneously on individual cells using metal-chelating polymer (MCP) based reagents. However, MC can in principle detect up to 135 parameters with the development of new elemental mass tags. Here we report the development of a tantalum oxide nanoparticle (NP)-based mass tag for MC immunoassays. Uniform-sized amine-functionalized tantalum oxide NPs ( d ∼ 5.7 nm) were synthesized via a one-pot two-step reverse microemulsion method. These amine-functionalized NPs were further modified with azide groups by reacting with azide-PEG 2 k succinimidyl carboxymethyl ester (NHS-PEG 2 k -N 3 ) cross-linkers. The Ab-NP conjugates were prepared by reacting azide-functionalized NPs with dibenzocyclooctyne (DBCO)-functionalized primary or secondary Abs (DBCO-Ab) followed by fast protein size exclusion liquid chromatography (FPLC) purification. Three Ab-NP conjugates (TaO 2 -PEG 2 k -goat antimouse, TaO 2 -PEG 2 k -CD25, TaO 2 -PEG 2 k -CD196) were fabricated and tested in MC immunoassays. For the TaO 2 -PEG 2 k -goat antimouse conjugate, we showed that it can effectively detect abundant CD20 biomarkers on Ramos cells. For TaO 2 -PEG 2 k -CD25 and TaO 2 -PEG 2 k -CD196 conjugates, we demonstrated that these Ab-NP conjugates could be integrated into the commercial Ab staining panels for high-dimensional single-cell immune profiling of human peripheral blood mononuclear cells.

Carbazole structures are of high interest in photopolymerization due to their enhanced light absorption properties in the near-UV or even visible ranges. Therefore, type I photoinitiators combining the carbazole chromophore to the well-established phosphine-oxides were proposed and studied in this article. The aim of this article was to propose type I photoinitiators that can be more reactive than benchmark phosphine oxides, which are among the more reactive type I photoinitiators for a UV or near-UV light emitting diodes (LED) irradiation. Two molecules were synthesized and their UV-visible light absorption properties as well as the quantum yields of photolysis and photopolymerization performances were measured. Remarkably, the associated absorption was enhanced in the 350-410 nm range compared to benchmark phosphine oxides, and one compound was found to be more reactive in photopolymerization than the commercial photoinitiator TPO-L for an irradiation at 395 nm.

La 0.7 Sr 0.3 MnO 3 (LSMO) nanoparticles have been obtained via solution combustion synthesis (SCS) using urea and glycine as fuels. Also, La 0.7 Sr 0.27 Ca 0.03 MnO 3 (LSCMO) nanoparticles have been synthesized through solution combustion using urea as fuel. In this paper, the combustion process was carried out with a fuel to oxidant ratio giving fuel deficient conditions ( ). The thermal analysis (TGA) indicate that the organic residues from the urea-nitrates gel mixture are eliminated above 600 °C and the post-synthesis heat treatment yields the formation of the desired phase without impurities. The obtained phases were analyzed using X-ray diffraction. The infrared analysis confirms the purity of the samples obtained using urea. However, the sample obtained using glycine confirms the formation of SrCO 3 . The morphology was analyzed using a FE-SEM microscope, and it was found that the particles present a spherical shape with a mean size of around 45 nm in the selected samples. The samples' energy dispersive X-ray spectra show that the desired elements (La, Sr, Ca, Mn and O) are present in the nanoparticles. The measured zero field cooled (ZFC) and field cooled (FC) magnetizations were recorded from 4.5 to 380 K at 105 A/m to obtain their blocking and Curie temperatures. Moreover, the hysteresis loops measured at room temperature confirm the superparamagnetic behavior of the elaborated samples. According to the results obtained, these nanoparticles have interesting properties that make them candidates to explore not only for their potential in biomedical applications but also in refrigeration and magnetic storage devices.

To improve the bio-performances of polyetheretherketone (PEEK) for orthopedic applications, submicro-particles of niobium pentoxide (Nb2O5) were synthesized using a sol-gel method, and PEEK/Nb2O5 composites (PNC) with a Nb2O5 content of 25v% (PNC25) and 50v% (PNC50) were fabricated by utilizing a process of pressing-sintering. The results showed that the Nb2O5 particles were not only dispersed in the composites but also exposed on the surface of the composites, which formed submicro-structural surfaces. In addition, the hydrophilicity, surface energy, surface roughness and absorption of proteins of the composites were improved with increasing Nb2O5 content. Moreover, the release of Nb ions with the highest concentration of 5.01 × 10-6 mol L-1 from the composite into the medium displayed no adverse effects on cell proliferation and morphology, indicating no cytotoxicity. Furthermore, compared with PEEK, the composites, especially PNC50, obviously stimulated adhesion and proliferation as well as osteogenic differentiation of bone mesenchymal stem cells of rats. The results suggested that the incorporation of Nb2O5 submicro-particles into PEEK produced novel bioactive composites with improved surface properties, which played important roles in regulating cell behaviors. In conclusion, the composites, especially PNC50 with good cytocompatibility and promotion of cellular responses, exhibited great potential as implantable materials for bone repair.

Colorimetric assays have drawn increasing research interest with respect to the quantitative detection of hydrogen peroxide (H 2 O 2 ) based on artificial enzymes because of their advantages with respect to natural enzymes, including design flexibility, low cost, and high stability. Regardless, the majority of the artificial enzymes exhibit low affinity to H 2 O 2 with large Michaelis-Menten constants ( K m ). This indicates that the catalytic oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to blue-colored oxTMB requires a high H 2 O 2 concentration, hindering the sensitivity of the colorimetric assay. To address this problem, novel reduced Co 3 O 4 nanoparticles (R-Co 3 O 4 ) have been synthesized in this study via a step-by-step procedure using ZIF-67 as the precursor. R-Co 3 O 4 exhibits a considerably enhanced peroxidase-like activity when compared with that exhibited by pristine Co 3 O 4 (P-Co 3 O 4 ). The catalytic process in the case of R-Co 3 O 4 occurs in accordance with the typical Michaelis-Menten equation, and the affinity of R-Co 3 O 4 to H 2 O 2 is apparently higher than that of P-Co 3 O 4 . Furthermore, the density functional theory calculations revealed that the introduction of oxygen vacancies to R-Co 3 O 4 enhances its H 2 O 2 adsorption ability and facilitates the decomposition of H 2 O 2 to produce ·OH radicals, resulting in improved peroxidase-like activity. A simple and convenient colorimetric assay has been established based on the excellent peroxidase-like activity of R-Co 3 O 4 for detecting H 2 O 2 in concentrations of 1-30 μM with a detection limit of 4.3 × 10 -7 mol/L (S/N = 3). Furthermore, the R-Co 3 O 4 -based colorimetric method was successfully applied to glucose detection in human serum samples, demonstrating its potential for application in complex biological systems.

By means of a simple and photo-induced method, four colors of molybdenum oxide quantum dots (MoO x QDs) have been synthesized, using Mo(CO) 6 as the structural guiding agent and molybdenum source. The as-prepared MoO x QDs display diverse optical properties due to the different configurations of oxygen vacancies in various nanostructures. Among them, crystalline molybdenum dioxide (MoO 2 ) with a deep blue color shows the most intense localized surface plasmon resonance effect in the near-infrared (NIR) region. The strong NIR absorption endows MoO 2 QDs with a high photothermal conversion efficiency of 66.3%, enabling broad prospects as a photo-responsive nanoagent for photothermal therapy of cancer. Moreover, MoO 2 QDs can also serve as a novel semiconductor substrate for ultrasensitive surface-enhanced Raman scattering (SERS) analysis of aromatic molecules, amino acids and antibiotics, with SERS performance comparable to that of noble metal-based substrates. The therapeutic applications of MoO 2 QDs open up a new avenue for tumor nanomedicine.

Hybrid, e.g., organic inorganic, perovskites from the type methylammonium lead iodide CH 3 NH 3 PbI 3 are promising solar cell materials. However, due to the large parameter space spanned by the manifold combinations of divalent metals with organic cations and anions, an efficient approach is needed to rapidly test and categorize new promising materials. Herein, we developed a high throughput approach for the automated synthesis of perovskite layers with different precursor ratios at varying annealing temperatures. The layers were analyzed by optical absorption and photoluminescence (PL) spectroscopy as well as X-ray diffraction (XRD) and evaluated using two different procedures. The first one is a stepwise exclusion of nonperforming reactant ratios and synthesis conditions by using both spectroscopic techniques, followed by a final validation of the procedure by XRD. In the second procedure, only PL results were consulted in combination with high throughput screening using design of experiments (DoE) to reduce the total number of experiments needed and compared to the manual cascade approach. Noteworthy, by simple PL screening, it was possible to identify the best ratio of perovskite to byproducts and annealing temperature. Thus, only with PL, more detailed results as with the manual protocol were reached, while at the same time the effort for characterization was significantly reduced (by 60% of the experimental time). In conclusion, our approach opens a way toward fast and efficient identification of new promising materials under different reaction and process conditions.

Para-, or 4-nitrophenol, and related nitroaromatics are broadly used compounds in industrial processes and as a result are among the most common anthropogenic pollutants in aqueous industrial effluent; this requires development of practical remediation strategies. Their catalytic reduction to the less toxic and synthetically desirable aminophenols is one strategy. However, to date, the majority of work focuses on catalysts based on precisely tailored, and often noble metal-based nanoparticles. The cost of such systems hampers practical, larger scale application. We report a facile route to bulk cobalt oxide-based materials, via a combined mechanochemical and calcination approach. Vibratory ball milling of CoCl 2 (H 2 O) 6 with KOH, and subsequent calcination afforded three cobalt oxide-based materials with different combinations of CoO(OH), Co(OH) 2 , and Co 3 O 4 with different crystallite domains/sizes and surface areas; Co@100, Co@350 and Co@600 ( Co@###; # = calcination temp). All three prove active for the catalytic reduction of 4-nitrophenol and related aminonitrophenols. In the case of 4-nitrophenol, Co@350 proved to be the most active catalyst, therein its retention of activity over prolonged exposure to air, moisture, and reducing environments, and applicability in flow processes is demonstrated.

Ionic liquids (ILs) and deep eutectic solvents (DESs) have proven to be suitable solvents and reactants for low-temperature reactions. To date, several attempts were made to apply this promising class of materials to metal oxide chemistry, which, conventionally, is performed at high temperatures. This review gives an overview about the scientific approaches of the synthesis as well as the dissolution of metal oxides in ILs and DESs. A wide range of metal oxides along with numerous ILs and DESs are covered by this research. With ILs and DESs being involved, many metal oxide phases as well as different particle morphologies were obtained by means of relatively simple reactions paths. By the development of acidic task-specific ILs and DESs, even difficultly soluble metal oxides were dissolved and, hence, made accessible for downstream chemistry. Especially the role of ILs in these reactions is in the focus of discussion., Competing Interests: The authors declare no conflict of interest.

Bacterial brown stripe (BBS) is one of the most economically important diseases of rice caused by Acidovorax oryzae (Ao). In order to ensure food security and safe consumption, the use of non-chemical approach is necessary. In this study, MgO and MnO 2 were synthesized using chamomile flower extract. The synthesized MgO and MnO 2 nanoparticles were characterized by UV-Visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission/scanning electron microscopy. The sizes were 18.2 and 16.5 nm for MgO and MnO 2 nanoparticles, respectively. The MgO and MnO 2 nanoparticles reduced the growth of Ao strain RS-2 by 62.9 and 71.3%, respectively. Also, the biofilm formation and swimming motility were significantly reduced compared to the control. The antibacterial mechanisms of MgO and MnO 2 nanoparticles against RS-2 reveals that MgO and MnO 2 nanoparticles penetrated the cells and destroyed the cell membrane leading to leakage of cytoplasmic content. Also, the flow cytometry observation reveals that the apoptotic cell ratio of RS-2 increased from 0.97% to 99.52 and 99.94% when treated with MgO and MnO 2 nanoparticles, respectively. Altogether, the results suggest that the synthesized MgO and MnO 2 nanoparticles could serve as an alternative approach method for the management of BBS.

Herein, we report a turn-on strategy for selectively killing the tumor cell via combining the singlet-oxygen quenching MnO 2 and tumor cell-targeting aptamer. The photosensitizers were in the quenching state when loaded in the mesoporous MnO 2 (mMnO 2 ) nanoparticles and sealed by the aptamer on the particle surface. The aptamer can selectively recognize the specific membrane protein on the tumor cell and release the photosensitizers, activating the photosensitizer and killing the tumor cells. The specific binding-induced "off-on" switching of singlet oxygen generation reduced the damage to the nearby healthy cells to a large extent. The high loading ability for photosensitizer and the GSH consumption property of mMnO 2 endow the system with high local concentration of singlet-oxygen for killing the target tumor cell. The high selectivity and efficiency of the constructed singlet oxygen regulating system will pave a new way for utilizing PDT in cancer precise treatment., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In this work, we successfully developed a novel and sensitive gas sensor for the determination of trace acetophenone based on its cataluminescence (CTL) emission on the surface of nano-praseodymium oxide (nano-Pr 6 O 11 ). The effects of working conditions such as temperature, flow rate, and detecting wavelength on the CTL sensing were investigated in detail. Under the optimized conditions, the sensor exhibited linear response to the acetophenone in the range of 15-280 mg/m 3 (2.8-52 ppm), with a correlation coefficient ( R 2 ) of 0.9968 and a limit of detection (S/N = 3) of 4 mg/m 3 (0.7 ppm). The selectivity of the sensor was also investigated, no or weak response to other compounds, such as alcohols (methanol, ethanol, n -propanol, iso -propanol, n -butanol), aldehyde (formaldehyde and acetaldehyde), benzenes (toluene, o -xylene, m -xylene, p -xylene), n -pentane, ethyl acetate, ammonia, carbon monoxide, carbon dioxide. Finally, the present sensor was applied to the determination of acetophenone in human exhaled breath samples. The results showed that the sensor has promising application in clinical breath analysis.

In this work, we demonstrate a facile method for colloidal lead halide perovskite nanoplatelet synthesis (Chemical formula: L2[ABX3]n-1BX4, L: butylammonium and octylammonium, A: methylammonium or formamidinium, B: lead, X: bromide and iodide, n: number of [BX6] 4- octahedral layers in the direction of nanoplatelet thickness) via ligand-assisted reprecipitation. Individual perovskite precursor solutions are prepared by dissolving each nanoplatelet constituent salt in N,N-dimethylformamide (DMF), which is a polar organic solvent, and then mixing in specific ratios for targeted nanoplatelet thickness and composition. Once the mixed precursor solution is dropped into nonpolar toluene, the abrupt change in the solubility induces the instantaneous crystallization of nanoplatelets with surface-bound alkylammonium halide ligands providing colloidal stability. Photoluminescence and absorption spectra reveal emissive and strongly quantum-confined features. X-ray diffraction and transmission electron microscopy confirm the two-dimensional structure of the nanoplatelets. Furthermore, we demonstrate that the band gap of perovskite nanoplatelets can be continuously tuned in the visible range by varying the stoichiometry of the halide ion(s). Lastly, we demonstrate the flexibility of the ligand-assisted reprecipitation method by introducing multiple species as surface-capping ligands. This methodology represents a simple procedure for preparing dispersions of emissive 2D colloidal semiconductors.

Structure-activity relationships for rigid analogues of combretastatin A-4 (CA-4) were investigated, leading to the discovery of a series of 3,4-diaryl-1,2,5-oxadiazole-N-oxides. Among them, 7n' and 7n'' showed remarkable antiproliferative activities against three cancer cell lines in nanomolar concentrations. Interestingly, 7n' inhibited tubulin polymerization much more efficiently than CA-4. Cellular mechanism investigation elucidated 7n' disrupted the cellular microtubule structure, arrested cell cycle at G 2 /M phase and induces apoptosis. Molecular modeling study revealed 1,2,5-oxadiazole-N-oxide ring could increase a hydrogen bond interaction with the binding site. These results provide impetus and further guidance for the development of new CA-4 analogues., (Copyright © 2019. Published by Elsevier Masson SAS.)

Photodynamic therapy (PDT) was considered as an effective treatment. Whereas only PDT is not enough to achieve effective therapy on account of irradiation intensity decreases as depth increases as well as tumor hypoxia. Combination with gene therapy and photodynamic therapy have emerged as an effective strategy to improve therapeutic effectiveness. In the present study, a GSH responsive MnO 2 was employed to delivery TB and DNAzyme for cancer imaging and PDT-gene combination treatment. TB, a photosensiters with aggregation-induced emission characteristic, was employed for photodynamic therapy, while DNAzyme, acting as catalysts for the degradation of EGR-1 mRNA, was exploited for gene silencing. All of the results of tumor treatment in vitro have implied that MnO 2 -DNAzyme-TB nanocomposite (MDT) can internalize into cells. Subsequently, MDT could decrease the expression of EGR-1 by gene silencing that enabling inhibition of cell growth. In addition, the singlet oxygen which was generated by the aggregated TB were able to further suppress cell growth. Combination therapy of photodynamic as well as gene therapy greatly enhanced antitumor efficiencies. Furthermore, in vivo tumor treatment experiments demonstrated that MDT under illumination can effectively inhibit the tumor growth of MCF-7 tumor-bearing mice by photodynamic and gene silencing combination therapy., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This report outlines an ultrasensitive electrochemiluminescence (ECL) sensing platform based on water-soluble tungsten oxide quantum dots (WO x QDs) for the detection of dopamine (DA) released from P12 cells. The WO x QDs with good stability and water solubility were prepared by a facile and green hydrothermal method, and used to modify a glassy carbon electrode (WO x QDs/GCE). The proposed ECL sensor exhibited a stable and strong cathodic ECL signal when potassium peroxodisulfate (K 2 S 2 O 8 ) as the coreactant in aqueous solution. The possible ECL mechanism was studied and deduced, and the ECL response signal of the proposed sensor decreased rapidly in the presence of dopamine (DA). Under optimal conditions, the ECL signals of WO x QDs linearly decreased with the increase of DA concentration in the range of 10 -15  M to 10 -9  M and 10 -9  M to 10 -5  M, respectively. The detection limit was as low as 10 -15  M (S/N = 3). Based on these results, this method has been successfully applied to the determination of DA released by PC12 cells. The detection linear range for the detection of DA released by PC12 cells was from 0.1 to 0.9 μM with a detection limit of 0.045 μM. Therefore, the proposed ECL sensor displayed high sensitivity, good specificity and long-term stability, which may shed light on a new way to construct other high-performance ECL detection systems based on WO x or WO x QDs-based nanocomposites., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Antibacterial agents are an important tool in the prevention of bacterial infections. Inorganic materials are attractive due to their high stability under a variety of conditions compared to organic antibacterial agents. Herein tungsten oxide nanodots (WO 3-x ), synthesized by a simple one-pot synthetic approach, were found to exhibit strong antibacterial capabilities. The analyses with colony-forming units (CFU) showed an excellent antibacterial activity of WO 3-x against both Gram-negative Escherichia coli ( E. coli ) and Gram-positive Staphylococcus aureus ( S. aureus ) strains. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images revealed clear damages to the bacterial cell membranes, which was further confirmed by molecular dynamics simulations. Additionally, exposure to simulated sunlight was found to further increase the germicidal activity of WO 3-x nanodots, a 30 min exposure to sunlight combined with 50 μg/mL WO 3-x nanodots showed a 70% decrease in E. coli viability compared to without exposure. Electron spin resonance spectroscopy (ESR) was used to elucidate the underlying mechanism of this photocatalytic activity through the generation of hydroxyl radical species. The cell counting kit-8 (CCK-8) and the live/dead assay were further employed to evaluate the cytotoxicity of WO 3-x nanodots on eukaryotic cells, which demonstrated their general biocompatibility. In summary, our results suggest WO 3-x nanodots have considerable potential in antibacterial applications, while also being biocompatible at large.

The existence of Cr(VI) and antibiotics in the environment can form the joint contaminant which can be hazardous to the ecosystem. To deal with this, we have explored a plausible method to remove the Cr(VI) and tetracycline (TC) from water by visible light photocatalysis. In this study, a series of reduced graphene oxide@ZnAlTi layered double oxides (rGO@LDO) composites with different doping ratio of rGO were successfully synthesized, which were applied in photocatalytic reduction of Cr(VI) and oxidation of TC. Graphene acts as an electron donor and it can enhance the adsorption of Cr(VI) and TC on the surface of the composites. It's found that the obtained ZnAlTi-LDO composites doped with rGO have higher photo-responsiveness in the visible region. The best-performing rGO@LDO composite (i.e., CGL3) exhibited enhanced visible light-driven photocatalytic Cr(VI) reduction, which was about five times higher than those of ZnAlTi-LDO (without adding hole catcher). The rGO@LDO also showed a satisfactory performance for photocatalytic oxidation of TC with the total organic carbon removal of 80%. However, the doping of rGO did not significantly enhance the removal of TC. The experiment of pH effects demonstrated that acidic pH was favorable to photocatalytic reduction of Cr(VI), while neutral pH was favorable to photocatalytic oxidation of TC. The band structure of ZnAlTi-LDO was first identified, and the E VB and E CB of ZnAlTi-LDO are -2.32 and 0.72 V (vs. RHE). This research provides a feasible method to remove Cr(VI) and tetracycline from water by employing ZnAlTi-LDO doped with rGO as photocatalyst., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In this study, amorphous Mn oxides (AMOs) and their composites with biochar (BC) were synthesized using different sugars (glucose, sucrose, and molasses), and their sorption efficiency toward Zn(II), Cd(II), and As(V) was tested. Additionally, detailed characterization of synthesized materials using various solid-state analysis methods (e.g. XRD, FTIR-ATR, and/or SEM-EDX) was also performed. Despite glucose-based AMOs presented higher sorption efficiency for As(V), i.e., 0.73 mmol g -1 (glucose) > 0.27 mmol g -1 (sucrose and molasses), similar sorption efficiency toward Zn(II), i.e., 0.80 mmol g -1 (glucose and molasses) > 0.66 (sucrose) and Cd(II) (0.71-0.74 mmol g -1 (sucrose and molasses) > 0.36 mmol g -1 (glucose), was observed for sucrose- and molasses-based AMOs under the given conditions. Next, the sorption efficiency of all AMO/BC composites was proportional to their AMO content. Finally, Mn(II) leaching from the structure of the new AMOs was negligible compared to that observed for the glucose-based AMOs, in this study as well as in other similar studies. Moreover, using molasses as reducing agent during AMO synthesis dramatically decreased the total cost of the final materials, which suggested that these new AMOs could represent interesting alternatives for standard remediation technologies. The AMOs synthesized using low-cost sugars could, therefore, be promising materials for real field applications, since the main disadvantages of using standard AMOs are mitigated. Nevertheless, the efficiency and stability of these composites under real-life conditions must be tested prior to their direct application for remediation technologies., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The authors present a colorimetric method for the evaluation of the hydroxyl radical scavenging capability of antioxidants by exploiting carbon-confined mixed cobalt oxide nanoparticles (denoted as C-confined CoO x NPs) as a novel peroxidase mimic. The nanozyme can be prepared from the metal-organic framework ZIF-67 by calcination at a moderate temperature. It exhibits peroxidase-mimicking activity and catalyzes the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) to form a blue product in the presence of H 2 O 2 via generation of hydroxyl radicals. However, in the presence of an antioxidant, the color reaction is suppressed due to scavenging of hydroxyl radicals by the antioxidant. Based on this principle, the hydroxy radical scavenging ability of glutathione (GSH), cysteine (Cys), tannic acid (TA) and tea polyphenols (TP) was assessed. It was found that these antioxidants can scavenge hydroxyl radicals in the following decreasing order: TA>Cys>GSH>TP. The assay was also used to quantify the antioxidative power of common fruit extracts. Graphical abstract Schematic presentation for evaluating the hydroxyl radical scavenging ability of different antioxidants using carbon-confined mixed cobalt oxide nanoparticles (denoted as C-confined CoO x NPs) as a highly active peroxidase mimic. With excellent activity, the C-confined CoO x NPs together with the visible peroxidase reaction can be employed as a powerful tool to rapidly screen appropriate antioxidants from natural samples and measure their activity for guiding their usage in related products.

In this work, strontium cerate nanoparticles (SrCeO 3 NPs, SC NPs) were developed through facile synthetic techniques (Ultrasound-Assisted (UA) and Stirring-Assisted (SA) synthesis) and utilized as an electrocatalyst for the selective and sensitive electrochemical detection of calcium channel blocker nifedipine (NDF). The as-prepared UASC NPs and SASC NPs were characterized using XRD, Raman, TEM, EDS, mapping, XPS and BET analysis which exposed the formation of SC NPs in the form of spherical in shape and well crystalline in nature. BET studies reveal that UASC NPs have maximum surface area than that of SASC NPs. Further, the use of the as-developed UASC NPs and SASC NPs as an electrocatalyst for the detection of NDF. Interestingly, the UASC NPs modified screen printed carbon electrode (UASC NPs/SPCE) exhibited an excellent electrocatalytic activity in terms of lower reduction potential and enhanced reduction peak current when compared to SASC NPs and unmodified SPCE. Moreover, as-prepared UASC NPs/SPCE displayed wide linear response range (LR, 0.02-174 µM), lower detection limit (LOD, 5 nM) and good sensitivity (1.31 µA µM -1  cm -2 ) than that of SASC NPs (LR = 0.02-157 µM, LOD = 6.4 nM, sensitivity - 1.27 µA µM -1 cm -2 ). Furthermore, UASC NPs/SPCE showed an excellent selectivity even in the existence of potentially co-interfering compounds such as similar functional group containing drugs, pollutants, biological substances and some common cations/anions. The developed sensor was successfully employed for the determination of NDF in real lake water, commercial NDF tablet and urine samples with acceptable recovery., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A simple and efficient protocol for the oxidation of trifluoromethyl, mono- and difluoromethyl sulfides to the corresponding sulfoxides without over-oxidation to sulfones, using TFPAA prepared in situ from trifluoroacetic acid and 15% H₂O₂ aqueous solution was developed. The methodology is suitable for a wide range of aromatic and aliphatic substrates in milligram and multigram scales.

We previously synthetized molybdenum oxide (MoO3) nanoparticles (NP) and showed their antibacterial activity against a representative collection of the most relevant bacterial species responsible for hospital-acquired infections, including Staphylococcus aureus. The aim of the present study was to prepare and characterize a novel coating with these MoO3 NP, confirm its mechanical stability, and investigate its biocidal effect to reduce S. aureus contamination on inanimate surfaces. In addition, the novel MoO3 NP coating was compared to a silver (Ag) NP coating synthetized by the same procedure. The MoO3 and Ag NP coatings were characterized in terms of their chemical structure by FT-IR, surface morphology by scanning electron microscopy, and mechanical properties by tensile and adhesion tests. The antimicrobial activity of the coatings was tested by following the loss of viability of S. aureus after 6h, 24h, 48h, and 72h exposure. MoO3 and Ag coatings exhibited surfaces of comparable morphologies and both presented elastomeric properties (tensile strength of ~420 kPa, Young's modulus of ~48 kPa, and maximum elongation of ~12%), and excellent (classification of 5B) adhesion to glass, steel and polystyrene surfaces. The two coatings exhibited a good antibacterial activity (R) against S. aureus over time (RMoO3 = 0.2-0.81; RAg = 0.61-2.37), although the effect of the Ag NP coating was more pronounced, especially at 72h (RMoO3 = 0.81 vs RAg = 2.37). Noteworthy, contrary to the Ag NP coating, the MoO3 NP coating was colourless and transparent, avoiding undesired unaesthetic effects. The synthetized coating with NP of MoO3, which has low toxicity to humans, capability of biodegradation, and rapid excretion, can be applied onto most standard materials and therefore is a promising tool to reduce S. aureus contamination on usual inanimate surfaces found in healthcare and community environments., Competing Interests: The authors have declared that no competing interests exist.

As one kind of redox active layered transition-metal dioxide nanomaterials, single-layer manganese dioxide (MnO 2 ) nanosheets have gained significant research attention in the fields of biosensing and biomedicine because of their large surface area, intense and broad optical absorption, strong oxidation ability, catalytic activity, and robust mechanical properties. This review provides a brief overview of the recent advances in the development of MnO 2 nanosheet-based biosensors, bioimaging as well as drug delivery for cancer therapy. The methodologies for the preparation of MnO 2 nanosheets are summarized, followed by an introduction of the nanostructure and properties of MnO 2 nanosheets. Special attention is paid to their applications in biosensing, bioimaging and cancer therapy. Future perspectives and the challenges of high-performance MnO 2 nanosheets are also discussed.

Highly efficient, visible light-driven and a novel ternary hybrid photocatalyst WO 3 -TiO 2 -g-C 3 N 4 with robust stabilities and versatile properties has been synthesized through facile hydrothermal method. This study considers the photo-degradation of aspirin (acetylsalicylate) and caffeine (methyl-theobromine) via photocatalysts (WO 3 , WO 3 /TiO 2, and WO 3 /TiO 2 /g-C 3 N 4 (WTCN) composite) under visible-light irradiation. The SEM and TEM images show the formation of WO 3 nanoparticles with orthorhombic structure and average particle size of 65 nm. The photocatalyst WTCN composite possesses higher-catalytic activity when compared to that of WO 3 and WO 3 /TiO 2 for degradation of aspirin and caffeine. The incorporation of g-C 3 N 4 in WO 3 /TiO 2 composite exhibited significant influence on the photocatalytic performance for both pollutants. Excellent photocatalytic performance of WTCN composite was observed owing to hydroxyl radical (OH) and superoxide radical (O 2 - ) as main active species. The enhanced photocatalytic activity of WTCN composite can be attributed to following three reasons: (1) extended visible-light absorption; (2) extended surface area; (3) efficient charge-separation due to synergistic effects between g- and WO 3 /TiO 2 composite. The removal efficiency of aspirin and caffeine (Methyl theobromine) could be achieved as much as 98% and 97% for acetylsalicylate and methyl-theobromine using WTCN composite material, respectively. This study could provide new insights into the synthesis of novel WO 3 -based materials for environmental and energy applications., (Copyright © 2018 Elsevier B.V. All rights reserved.)

This work reports an efficient diastereoselective synthetic methodology for the preparation of phosphorus substituted cyanoaziridines through the nucleophilic addition of TMSCN, as cyanide source, to the C-N double bond of 2H-azirine derivatives. The aziridine ring, in these novel cyanoaziridines, can be activated by simple N-tosylation or N-acylation. In addition, the cytotoxic effect on cell lines derived from human lung adenocarcinoma (A549) and human embryonic kidney (HEK293) was also screened. N-H and N-Substituted cyanoaziridines showed excellent activity against the A549 cell line in vitro. Moreover, selectivity towards cancer cell (A549) over (HEK293), and non-malignant cells (MCR-5) has been observed., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

The LaFeO 3 perovskite oxide decorated active carbon fibers (LFO-ACFs) based on cotton fabric waste were successfully synthesized through sol-gel loading and thermal treatment. LaFeO 3 perovskite and cotton fabric waste were combined to an eco-friendly and cheap adsorbent, which could reuse the leftover materials of textile industry and realize their functional modification. The structural, morphology/microstructure and functional groups were investigated through X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Fourier Transform Infrared spectroscopy (FTIR), respectively. The XRD pattern suggested the cotton fabric matrix didn't influence the structure of LaFeO 3 perovskite oxide. In SEM studies, LFO-ACFs still maintained fibrous shape of the raw cotton fibers, and the EDX analysis showed that the main elements of the prepared LFO-ACFs were La, Fe, O and C. The synthesized LFO-ACF was employed for adsorption of cational dye of Rhodamine B (RhB), and the effects of adsorption parameters, i.e. pH, contact time, solution temperature and initial concentration of dye, on adsorption behavior were investigated. Results suggested the adsorption performance of LFO-ACF for RhB was nearly not affected by solution pH and its maximum adsorption capacity fitted by the Langmuir isothermal model could attain 182.6 mg/g at 293 K. The adsorption kinetics followed the pseudo-second-order equation and the regeneration of LFO-ACF could be well realized through an easy pyrolysis method., (Copyright © 2018. Published by Elsevier Inc.)

89 Sr and 90 Sr are both fission products of high radiotoxicity, which can be released in significant amounts in the event of a nuclear accident. Radiostrontium isotopes will follow calcium all along the food chain and, after ingestion, accumulate in the bones. Therefore, it is imperative to be able to determine 89 Sr and 90 Sr in raw milk samples in case of an accidental situation to evaluate the dose given by both radionuclides to the population. Several methods exist for conducting 89 Sr and 90 Sr determination. However, most of them use at least one chromatographic step to purify strontium. This, unfortunately, increases the analytical time before the results can be released to the authorities. In addition, they often use liquid scintillation counting to determine the 89 Sr and 90 Sr activities, a method which can handle only one sample at a time. Here we propose using synthetic tunnel manganese oxides such as cryptomelane and todorokite and layered metal sulfides to selectively extract strontium from fresh milk and raw urine in a batch sorption method. We found that the method is very quick and yields very pure sources of (radio)-strontium, which can be counted in a proportional counter. Data (counts per minute) from the counter were fitted to a mathematical expression enabling the simultaneous determination of 89 Sr and 90 Sr. Because a proportional counter often has several drawers, it is typically possible to measure up to 16 samples at a time. Since cryptomelane is a binding phase easily synthesized in a large quantity, we anticipate that this technique could be an interesting alternative to conventional solid phase extraction chromatography methods., (Copyright © 2018 Elsevier B.V. All rights reserved.)