RESUMO
Fluorescent DNA nanosensors have been widely used due to their unique advantages, among which the near-infrared (NIR) imaging mode can provide deeper penetration depth and lower biological background for the nanosensors. However, efficient NIR quenchers require ingenious design, complex synthesis, and modification, which severely limit the development of NIR DNA nanosensors. Label-free strategies based on G-quadruplex (G4) and NIR G4 dyes were first introduced into in situ extracellular imaging, and a novel NIR sensing strategy for the specific detection of extracellular targets is proposed. The strategy avoids complex synthesis and site-specific modification by controlling the change of the NIR signal through the formation of a G4 nanostructure. A light-up NIR DNA nanosensor based on potassium ion (K+)-sensitive G4 chain PS2.M was constructed to verify the strategy. PS2.M forms a stable G4 nanostructure in the presence of K+ and activates the NIR G4 dye CSTS, thus outputting NIR signals. The nanosensor can rapidly respond to K+ with a linear range of 5-50 mM and has good resistance to interference. The nanosensor with cholesterol can provide feedback on the changes in extracellular K+ concentration in many kinds of cells, serving as a potential tool for the study of diseases such as epilepsy and cancer, as well as the development of related drugs. The strategy can be potentially applied to the NIR detection of a variety of extracellular targets with the help of functional DNAs such as aptamer and DNAzyme.
Assuntos
Corantes Fluorescentes , Nanoestruturas , Corantes Fluorescentes/química , DNA/química , Potássio/químicaRESUMO
This study aims to explore the acute effects of short-term exposure to PM2.5 components and their mixture on PROM. Counts of hospital admissions due to PROM were collected at the Fourth Hospital of Shijiazhuang. The associations between the PROM and PM2.5 components was examined using a time-stratified case-crossover approach. The overall effects of components on TPROM were examined using the BKMR. During the study period 30,709 cases of PROMwere identified. The relative risks and the 95% CI of TPROM were 1.013 (1.002, 1.028) and 1.015 (1.003, 1.028) associated with per interquartile range increase in nitrate and ammonium ion on the current day and they were 1.007 (1.001, 1.013) and 1.003 (1.000, 1.005) on the previous day. The results from the BKMR models showed a higher risk of TPROM was associated with exposure to mixtures, in which, nitrate and organic matter were the main contributors to the overall effect.
RESUMO
The ability to simply, selectively, and sensitively detect low numbers of miRNAs in clinical samples is highly valuable but remains a challenge. In this work, we present a novel miRNA detection system by using the elaborately designed hairpin switch, where the T7 primer, template, target recognize sequence, and light-up RNA aptamer template are edited and embedded in one single-stranded DNA hairpin structure. In the beginning, the hairpin switch maintained the hairpin structure 1, in which the ds promoter of T7 polymerase was disrupted, thus the transcription reaction of T7 polymerase was inhibited. After binding to the target, the hairpin switch 1 was unfolded and turned to the hairpin structure 2. This switch initiates the in vitro T7 transcription reaction, producing plenty of RNA transcripts containing RNA aptamers. Consequently, transcribed tremendous RNA aptamers lighted up the fluorophore for quantitative analysis. Compared with the existing T7 polymerase-based amplification system, this strategy exhibits several advantages, including simplicity, convenience, and high selectivity and sensitivity. The experimental results demonstrated that we could achieve the quantification of miRNA in buffer and complex biological samples.
Assuntos
Aptâmeros de Nucleotídeos , MicroRNAs , Aptâmeros de Nucleotídeos/genética , DNA de Cadeia Simples , Corantes Fluorescentes , Proteínas Fúngicas , MicroRNAs/genética , NucleotidiltransferasesRESUMO
AIM: Preeclampsia (PE) is a common medical complication of pregnancy characterized by high blood pressure and proteinuria after the 20th gestational week. This study aimed to investigate the potency of the combination of curcumin and aspirin in the treatment of PE and explore the underlying mechanisms. MATERIAL AND METHODS: The PE model was constructed in female rats by administering 0.5 mg/mL N-nitro-L-arginine methyl ester from gestational days (GDs) 6 to 16. The pregnant female rats were divided into five groups according to the drug treatment. The curcumin or aspirin was given to the rats by tail vein injection (0.36 mg/kg) or gavage treatment (1.5 mg/kg BW/day) from GD4 to GD18. RESULTS: Treatment with curcumin and aspirin combination significantly reduced the systolic blood pressure and proteinuria in the PE rats. Meanwhile, in comparison to the PE rats treated with single-dose curcumin or aspirin, the rats treated with combined curcumin and aspirin showed significantly decreased sFlt-1, increased placental growth factor, and alleviated oxidative stress in both blood and placental tissues, which are abnormal in no-treated PE rats. Furthermore, dramatically decreased inflammatory cytokines secretion and TLR4 and NF-κB p65 expression in placental tissues were also observed in the PE rats with combined treatment compared to those of no-treated, signal-dose curcumin or aspirin-treated PE rats. CONCLUSIONS: Our results suggested that the combined treatment of curcumin and aspirin significantly ameliorates the symptoms of PE in rats, which is most likely due to the inhibition of the placental TLR4/NF-κB p65 signaling pathway.
Assuntos
Curcumina , Pré-Eclâmpsia , Humanos , Ratos , Feminino , Gravidez , Animais , Aspirina/farmacologia , Aspirina/uso terapêutico , NF-kappa B/metabolismo , Placenta/metabolismo , Curcumina/farmacologia , Curcumina/metabolismo , Curcumina/uso terapêutico , Receptor 4 Toll-Like/metabolismo , Receptor 4 Toll-Like/uso terapêutico , Fator de Crescimento Placentário/metabolismo , Transdução de Sinais , Proteinúria/tratamento farmacológicoRESUMO
Theranostics, which combines both diagnostic and therapeutic capabilities in one dose, has always been an intractable challenge in personalized cancer treatment. Herein, a versatile nanotheranostic platform "nanoflare couple (NC)" has been developed for in situ multiplex cancer-related mRNA imaging and subsequent logic-controlled aggregation of gold nanoparticles, leading to gene therapy and photothermal therapy upon irradiation with infrared light. As a proof of concept, TK1 and survivin mRNAs that are highly expressed in most tumor tissues are selected as endogenous cancer indicators and therapy triggers to design the NC. Mice bearing breast cancer cells MCF-7 are prepared as a model to test its efficacy. The in vitro and in vivo assays validate that the NC show the capability for multiplexed mRNA imaging and high efficiency for logic-controlled combinational therapy of breast cancer.
Assuntos
Nanopartículas Metálicas , Nanopartículas , Animais , Linhagem Celular Tumoral , Terapia Combinada , Ouro , Lógica , Camundongos , Fototerapia , RNA Mensageiro/genética , Nanomedicina Teranóstica/métodosRESUMO
Direct, rapid, sensitive, and selective detection of nucleic acids in complex biological fluids is crucial for medical early diagnosis. We herein combine the trans-cleavage ability of clustered regularly interspaced short palindromic repeats (CRISPR)/Cas12a with Au-nanobeacon to establish a CRISPR-based biosensor, providing rapid miRNA detection with high speed and attomolar sensitivity. In this strategy, we first report that the trans-cleavage activity of CRISPR/cas12a, which was previously reported to be triggered only by target ssDNA or dsDNA, can be activated by the target miRNA directly. Therefore, this method is direct, i.e., does not need the conversion of miRNA into its complementary DNA (cDNA). Meanwhile, as compared to the traditional ssDNA reporters and molecular beacon (MB) reporters, the Au-nanobeacon reporters exhibit improved reaction kinetics and sensitivity. In this assay, the miRNA-21 could be detected with very high sensitivity in only 5 min. Finally, the proposed strategy enables rapid, sensitive, and selective miRNA determination in complex biological samples, providing a potential tool for medical early diagnosis.
Assuntos
Técnicas Biossensoriais , MicroRNAs , Sistemas CRISPR-Cas/genética , DNA/genética , DNA de Cadeia Simples/genética , MicroRNAs/genéticaRESUMO
The treatment of antibiotics wastewater by electrocatalytic oxidation has attracted much attention. In the paper, a novel halloysite bimetallic (HLS-Cu-Mn) particle electrode material was prepared and a bench-scale electrocatalytic reaction tank was designed. A three-dimensional electrocatalytic oxidation reactor composed of HLS-Cu-Mn and a bench-scale electrocatalytic reaction tank was used to degrade Sulfanilamide (SA) wastewater. Characterization of the synthesized material was conducted with Scanning electron microscopy (SEM), X-ray polycrystalline powder diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET). The electron spin resonance spectroscopy test results confirmed that HLS-Cu-Mn produced a large number of â¢OH. The electrochemical workstation confirmed that HLS-Cu-Mn had strong electrocatalytic activity and repolarization ability. Under the optimum preparation conditions and degradation process parameters, the removal efficiency of SA and TOC was 99.84% and 88.95% respectively. The method also has good degradation efficiency for aniline, phenol, herbicides, antibiotics, and dyeing wastewater. It was found that 4 main intermediates appeared in the degradation process by Ultra-high performance liquid chromatography/triple tandem quadrupole mass spectrometry (LC-MS). In sum, it was believed that this work provides a new vision and idea for water treatment.
Assuntos
Águas Residuárias , Poluentes Químicos da Água , Antibacterianos , Argila , Eletrodos , Oxirredução , Sulfanilamida , Águas Residuárias/química , Poluentes Químicos da Água/químicaRESUMO
In recent years, the structure of selenium-enriched polysaccharides and their application in immunomodulation have attracted much attention. In previous studies, we extracted and purified a novel selenium-enriched Pleurotus ostreatus polysaccharide called Se-POP-21, but its structure and immunomodulatory activity were still unclear. In this study, the main structural unit formula of Se-POP-21 was characterized by methylation analysis and an NMR experiment. The results showed that the backbone of Se-POP-21 was â[2,6)-α-D-Galp-(1â6)-α-D-Galp-(1]4â2,4)-ß-L-Arap-(1â[2,6)-α-D-Galp-(1â6)-α-D-Galp-(1]4â, branched chain of ß-D-Manp-(1â and ß-D-Manp-(1â4)-ß-L-Arap-(1â connected with â2,6)-α-D-Galp-(1â and â2,4)-ß-L-Arap-(1â,respectively, through the O-2 bond. In vitro cell experiments indicated that Se-POP-21 could significantly enhance the proliferation and phagocytosis of RAW264.7 cells, upregulate the expression of costimulatory molecules CD80/CD86, and promote RAW264.7 cells to secrete NO, ROS, TNF-α, IL-1ß, and IL-6 by activating the NF-κB protein. The results of this study indicate that Se-POP-21 can effectively activate RAW264.7 cells. Thus, it has the potential to be used in immunomodulatory drugs or functional foods.
Assuntos
Pleurotus , Selênio , Animais , Carboidratos da Dieta/metabolismo , Imunomodulação , Camundongos , Pleurotus/química , Polissacarídeos/química , Células RAW 264.7 , Selênio/químicaRESUMO
Gastric hypersensitivity is a major pathophysiological feature of functional dyspepsia (FD). Recent clinical studies have shown that a large number of patients with FD present with gastroduodenal microinflammation, which may be involved in the pathophysiology of FD. However, no animal model reflecting this clinical characteristic has been established. The underlying mechanism between microinflammation and FD remains unknown. In this study, using a maternal separation (MS)-induced FD model, we aimed to reproduce the gastroduodenal microinflammation and reveal the interaction between gastroduodenal microinflammation and gastric hypersensitivity. The MS model was established by separating newborn Sprague-Dawley rats for 2 h a day from postnatal day 1 to day 10. At 7-8 wk of age, electromyography was used to determine the visceromotor response to gastric distention (GD) and immunohistochemistry was performed to detect distension-associated neuronal activation as well as immunohistological changes. Our results demonstrated that MS-induced FD rats underwent gastric hypersensitivity with GD at 60 and 80 mmHg, which are related to increased p-ERK1/2 expression in the dorsal horn of T9-T10 spinal cords. Eosinophils, but not mast cells, were significantly increased in the gastroduodenal tract, and the coexpression rate of CD11b and major basic protein significantly increased in MS rats. Treatment with dexamethasone reversed gastric hypersensitivity in MS-induced FD rats by inhibiting eosinophil infiltration. These findings indicated that neonatal MS stress induces eosinophil-associated gastroduodenal microinflammation and gastric hypersensitivity in adulthood in rats. Microinflammation contributes to gastric hypersensitivity; therefore, anti-inflammatory therapy may be effective in treating patients with FD with gastroduodenal microinflammation.NEW & NOTEWORTHY We showed for the first time that neonatal MS stress-induced FD rats undergo gastroduodenal eosinophil-associated microinflammation in adulthood. Suppression of microinflammation attenuated gastric hypersensitivity in MS rats. These findings established a functional link between microinflammation and gastric hypersensitivity, which may provide a potential clue for the clinical treatment of FD.
Assuntos
Duodeno/patologia , Eosinófilos , Inflamação/patologia , Estômago/patologia , Animais , Animais Recém-Nascidos , Mucosa Gástrica/inervação , Mucosa Gástrica/patologia , Gastrite , Hipersensibilidade , Privação Materna , Pressão , Ratos , Ratos Sprague-Dawley , Estresse FisiológicoRESUMO
The K+ and Na+ levels in cells have a synergistic effect on many biological processes (BPs); therefore, the simultaneous detection of them is important. Here, we propose a novel Y-shaped DNA sensor for simultaneous monitoring of Na+ and K+ in extracellular microenvironments. The designed sensor contributed to the selective response to the above two ions. In addition, it performed the imaging of the above two ions on the cell surface in a real-time, on-site manner, which would shed more light on the association of the Na+/K+ content with regulatory BPs. We believe that this new strategy will be a promising tool to investigate the synergy of Na+/K+ in regulating different BPs.
Assuntos
Potássio , Sódio , Membrana Celular , DNA , ÍonsRESUMO
The intrinsic poor solubility and limited load capacity of ß-cyclodextrins (ß-CDs) results in reduced bioavailability, rendering the material unsuitable in complex biological environments. In this work, a pair of ß-CDs was methylated and covalently linked with acid-sensitive acylhydrazone and GSH-sensitive disulfide bonds to ensure a precise drug release pattern. The hydrophobic anticancer drug doxorubicin (Dox) was encapsulated inside the hydrophobic core of bis(ß-CD) via hydrophobic association with loading capacity of 24% in weight and a hydrodynamic size of about 100 nm. When exposed to acidic and reductive environments, the acylhydrazone and disulfide bonds were found to be cleaved, resulting in Dox release. Using fluorescence imaging and flow cytometry analysis, the designed bis(ß-CD) were determined to activate the drug release behavior by specific intracellular stimuli (pH and GSH). In vivo studies demonstrated specific drug delivery characteristics and controlled drug release behaviors in the tumor sites, giving rise to high antitumor activity and low toxicity. Taken in concert, this dual stimuli-responsive bis(ß-CD) with superior amphiphilicity and biocompatibility features showed great potential for future clinical applications.
Assuntos
Antineoplásicos/uso terapêutico , Glutationa/química , Nanopartículas , beta-Ciclodextrinas/química , Antineoplásicos/administração & dosagem , Sistemas de Liberação de Medicamentos , HumanosRESUMO
Novel ferrocene functionalized graphene with different molecular structures were designed, fabricated and characterized via SEM, EDS, FTIR, XPS and RAMAN methods. SEM results show the two-dimensional structure of the as-prepared catalysts, and the active metal Fe is uniformly distributed on the surface of graphene. The FTIR, XPS and RAMAN results confirmed the successful preparation of ferrocene functionalized graphene. The catalytic effects of the as-synthesized catalysts for the thermal decomposition of energetic TKX-50 were monitored by DSC, and the corresponding kinetic parameters were calculated using multi kinetic methods including traditional and nonlinear models. The results showed that the as-prepared ferrocene functionalized graphene can effectively promote the thermal decomposition of TKX-50 with the reduced decomposition peak temperatures and activation energies. In addition, the effects of ferrocene functionalized graphene for TKX-50 decomposition are reflected in both high and low temperature stages, and the effect on the high temperature stage is more significant. The outstanding catalytic activity of ferrocene functionalized graphene is related not only to the good dispersion of active Fe, but also to the enhanced interaction of small molecule products on two-dimensional graphene. Among the ferrocene functionalized graphene studied, G-792-Fe and G-902-Fe exhibit better catalytic effects on the thermal decomposition of TKX-50, which can be used as candidate catalysts for TKX-50-based solid propellants.
RESUMO
Herein we present the synthesis and characterization of a panel of structurally related zwitterionic piano-stool rhodium(III) and ruthenium(II) complexes. The identities of these novel complexes have been determined by NMR spectroscopy, mass spectrometry, elemental analysis and single-crystal X-ray crystallography. The stability and fluorescence property of these zwitterionic complexes were also confirmed. Zwitterionic rhodium(III) complexes Rh1-Rh4 displayed potent cytotoxic activity against A549 and HeLa human cancer cells. On the contrary, zwitterionic ruthenium(II) complexes Ru1-Ru4 presented no obvious cytotoxic activity to the test cell lines. Moreover, the trend that the introduction of fluorinated substituent and phenyl ring in the η5-CpR ring and N,N-chelating ligand, respectively, could enhance the cytotoxicity of these zwitterionic rhodium(III) complexes, were observed. The exploration of mechanism using flow cytometry displayed that the cytotoxicity of these rhodium(III) complexes was associated with the perturbation of the cell cycle and the induction of cell apoptosis. Furthermore, microscopic analysis using confocal microscopy indicated that the representative rhodium(III) complex Rh4 entered A549 cells via energy-dependent pathway and predominantly accumulated in lysosomes, thus leading to the disruption of lysosomal integrity.
Assuntos
Antineoplásicos/farmacologia , Compostos Organometálicos/farmacologia , Ródio/farmacologia , Rutênio/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Modelos Moleculares , Estrutura Molecular , Compostos Organometálicos/síntese química , Compostos Organometálicos/química , Ródio/química , Rutênio/química , Relação Estrutura-AtividadeRESUMO
Atractylodin (ATR) is a bioactive component found in dried rhizomes of Atractylodes lancea (AL) De Candolle. Although AL has accumulated empirical evidence for the treatment of pain, the molecular mechanism underlying the anti-pain effect of ATR remains unclear. In this study, we found that ATR increases transient receptor potential ankyrin-1 (TRPA1) single-channel activity in hTRPA1 expressing HEK293 cells. A bath application of ATR produced a long-lasting calcium response, and the response was completely diminished in the dorsal root ganglion neurons of TRPA1 knockout mice. Intraplantar injection of ATR evoked moderate and prolonged nociceptive behavior compared to the injection of allyl isothiocyanate (AITC). Systemic application of ATR inhibited AITC-induced nociceptive responses in a dose-dependent manner. Co-application of ATR and QX-314 increased the noxious heat threshold compared with AITC in vivo. Collectively, we concluded that ATR is a unique agonist of TRPA1 channels, which produces long-lasting channel activation. Our results indicated ATR-mediated anti-nociceptive effect through the desensitization of TRPA1-expressing nociceptors.
Assuntos
Furanos/metabolismo , Furanos/farmacologia , Canal de Cátion TRPA1/metabolismo , Analgésicos/metabolismo , Analgésicos/farmacologia , Animais , Cálcio/metabolismo , Canais de Cálcio/metabolismo , Gânglios Espinais/metabolismo , Células HEK293 , Humanos , Isotiocianatos/farmacologia , Lidocaína/análogos & derivados , Lidocaína/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neurônios/metabolismo , Nociceptividade/efeitos dos fármacos , Nociceptores/metabolismo , Dor/tratamento farmacológico , Ratos , Ratos Sprague-Dawley , Canal de Cátion TRPA1/agonistas , Canal de Cátion TRPA1/efeitos dos fármacos , Canais de Cátion TRPC/metabolismo , Canais de Potencial de Receptor Transitório/metabolismoRESUMO
The design of an intelligent nanoprobe capable of intracellular controlled release of apoptosis inducers and subsequent high-fidelity imaging of the drug-induced apoptosis is highly desirable for precise cancer treatment. Herein, we report an intelligent nanoprobe that combined therapeutic and imaging functions in one agent. Briefly, a gold nanoparticle is designed to be conjugated with acid-responsive DNA duplexes (Dox intercalates in this region) and caspase-3-specific cleavable peptides (labeled with fluorophore). We demonstrated that the nanoprobe could efficiently deliver an anticancer drug (Dox) into cancer cells and achieve acid-responsive drug release. Furthermore, the apoptotic process was in situ-monitored by detection of fluorescence through the cleavage of the peptide linker by caspase-3, which is one of the executioner caspases involved in apoptosis. This newly developed nanoprobe could serve as a theranostic agent for targeted responsive chemotherapy and also provide feedback apoptosis imaging of the self-therapeutic effect.
Assuntos
Antibióticos Antineoplásicos/farmacologia , Doxorrubicina/farmacologia , Ouro/química , Nanopartículas Metálicas/química , Células A549 , Antibióticos Antineoplásicos/química , Apoptose/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Doxorrubicina/química , Liberação Controlada de Fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Concentração de Íons de Hidrogênio , Imagem Óptica , Células Tumorais CultivadasRESUMO
Inspired by the natural enzyme cascade reaction, a multiple DNAzyme cascade platform is engineered to imitate the intracellular process of signal transduction and signal amplification. In this design, when particular stimuli appear, an activated upstream DNAzyme will cleave a well-designed intermediary S1, releasing a downstream DNAzyme that can cleave the reporter substrate S2 to output signals. Thus, the signal is passed from the upstream DNAzyme to the downstream DNAzyme through a well-designed intermediary, accomplishing signal transduction and signal amplification. According to the experimental results, the DNAzyme cascades are capable of improving sensitivity for bioassays compared with that for single DNAzyme-based biocatalysis, which holds promise for potential applications, such as biomolecular computing, logic circuits and precision medicine.
Assuntos
Técnicas Biossensoriais/métodos , DNA Catalítico/química , Engenharia Genética , MicroRNAs/sangue , Técnicas de Amplificação de Ácido Nucleico/métodos , Biocatálise , DNA Catalítico/genética , Humanos , Transdução de SinaisRESUMO
The rational design by the introduction of fluorine into a compound has achieved success in the development of organic anticancer drugs. However, the fluorine effect in metal-based anticancer complexes has rarely been reported. In this contribution, we report the synthesis, characterization, chemical reactivity, and biological activity of a series of half-sandwich zwitterionic iridium(III) complexes containing different substituents in the η5-CpR ring. The molecular structures for complexes Ir1-Ir4 and Ir7 were determined by single-crystal X-ray crystallography techniques. Notably, the asymmetrically substituted fluoro complexes Ir4 and Ir6 in solution show two conformational isomers. These complexes have sufficient stability, exhibit fluorescence emission, and show potent catalytic activity in converting NADH to NAD+. The effect of the substituents in the η5-CpR ring for these zwitterionic complexes on their anticancer activity was systematically investigated. Surprisingly, the presence of fluorinated substituents gives rise to a significant increase in the anticancer activity. The lipophilicity and cellular uptake levels of these complexes appeared to be the primary factors for their cytotoxicity in this system. A microscopic mechanism study showed that the typical complex Ir4 entered A549 cancer cells through an energy-dependent pathway and was mainly located in lysosomes. Furthermore, an increase in ROS level, apoptosis induction, and cell-cycle perturbation together contribute to the anticancer potency of these zwitterionic complexes.
Assuntos
Antineoplásicos/farmacologia , Complexos de Coordenação/farmacologia , Flúor/química , Irídio/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Cisplatino/química , Cisplatino/farmacologia , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Cristalografia por Raios X , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Irídio/química , Modelos Moleculares , Estrutura Molecular , Espécies Reativas de Oxigênio/análiseRESUMO
Thermal decomposition performance of the insensitive energetic compound 1,1-diamino-2,2-dintroethene (FOX-7) is essential for its application in the field of solid propellants. This study seeks to reveal the catalytic effects of reduced graphene oxide-bimetallic oxide nanocomposites (rGO-MFe2O4, M = Ni, Co, and Zn) on the thermal decomposition, kinetic parameters, and pyrolysis mechanism of energetic FOX-7. The results showed that the catalytic activities of the bimetallic iron oxide (NiFe2O4, CoFe2O4, and ZnFe2O4) increased obviously after anchoring on the surface of graphene. Particularly, the rGO-NiFe2O4 nanocomposite possessed the best catalytic activity for FOX-7 thermal decomposition. The high thermal decomposition peak temperature (THDP) and the apparent activation energy (Ea) of FOX-7 were decreased by 57.4 °C and 54.27 kJ mol-1 after mixing with the rGO-NiFe2O4 nanocomposite. The excellent catalytic activity of rGO-NiFe2O4 can be attributed to the synergistic interaction between rGO and NiFe2O4, which is beneficial for the reduction of activation energy and a high thermal decomposition peak temperature of FOX-7. This study is helpful for the rational design of a solid propellant containing FOX-7 and to understand the thermal decomposition kinetics and mechanism of FOX-7.
RESUMO
Molecularly imprinted polymers were prepared via ß-cyclodextrin-stabilized oil-in-water Pickering emulsion polymerization for selective recognition and adsorption of erythromycin. The synthesized molecularly imprinted polymers were spherical in shape, with diameters ranging from 20 to 40 µm. The molecularly imprinted polymers showed high adsorption capacity (87.08 mg/g) and adsorption isotherm data fitted well with Langmuir model. Adsorption kinetics study demonstrated that the molecularly imprinted polymers acted in a fast adsorption kinetic pattern and the adsorption features of molecularly imprinted polymers followed a pseudo-first-order model. Adsorption selectivity analysis revealed that molecularly imprinted polymers had a much better specificity for erythromycin than that for spiramycin or amoxicillin, and the relative selectivity coefficient values on the bases of spiramycin and amoxicillin were 3.97 and 3.86, respectively. The Molecularly imprinted polymers also showed a satisfactory reusability after four times of regeneration. In addition, molecularly imprinted polymers exhibited good adsorption capacities for erythromycin under complicated environment, that is, river water and milk. These results proved that the as-prepared molecularly imprinted polymers is a potent absorbent for selective recognition of erythromycin, and therefore it may be a promising candidate for practical applications, such as wastewater treatment and detection of erythromycin residues in food.
Assuntos
Eritromicina/análise , Leite/química , Polímeros Molecularmente Impressos/química , Rios/química , beta-Ciclodextrinas/química , Animais , Emulsões , Polímeros Molecularmente Impressos/síntese química , Polimerização , Água/químicaRESUMO
Ionic liquids (ILs) are acknowledged as green chemicals and favorable substitutes for volatile organic solvents, which are currently used. However, previous studies have shown that these compounds had toxicological impacts on aquatic organisms. To investigate the effects of 1-hexyl-3- methylimidazolium bromide ionic liquid ([C6mim]Br) on embryonic development and reproduction in water flea (Daphnia magna), a series of exposure experiments were conducted, including acute toxicity, maternal exposure, and chronic exposure tests. In acute toxicity experiment, D. magna neonates exhibited developmental abnormalities in the shell spine and the second antennae in a concentration-dependent manner after exposure to [C6mim]Br. The results in maternal exposure test also revealed a certain embryo-toxicity in response to [C6mim]Br in D. magna. However, the toxicity was lower than that conveyed by direct acute exposure, this indicated that the IL could act directly on organism. During the 21 days chronic exposure, the 1.6 mg/L exposure caused marked drop in the survival, molts and the number of the first brood of D. magna. Meanwhile, the total number of offspring was significantly declined in 1.6 mg/L concentration treatment groups, whereas increased in 0.2 mg/L groups. Generally, abnormalities in the offspring were significantly increased across all of the treatment groups in contrast to the control. No effect on sex differentiation was found during the experiments. These findings suggested that [C6mim]Br could affect embryonic development and reproduction in D. magna, and provided references for further study on the mechanisms underlying toxicological effects of ILs and the assessment of their potential environmental risks.