RESUMO
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), has seriously threatened global public health. Severe COVID-19 has been reported to be associated with an impaired IFN response. However, the mechanisms of how SARS-CoV-2 antagonizes the host IFN response are poorly understood. In this study, we report that SARS-CoV-2 helicase NSP13 inhibits type I IFN production by directly targeting TANK-binding kinase 1 (TBK1) for degradation. Interestingly, inhibition of autophagy by genetic knockout of Beclin1 or pharmacological inhibition can rescue NSP13-mediated TBK1 degradation in HEK-293T cells. Subsequent studies revealed that NSP13 recruits TBK1 to p62, and the absence of p62 can also inhibit TBK1 degradation in HEK-293T and HeLa cells. Finally, TBK1 and p62 degradation and p62 aggregation were observed during SARS-CoV-2 infection in HeLa-ACE2 and Calu3 cells. Overall, our study shows that NSP13 inhibits type I IFN production by recruiting TBK1 to p62 for autophagic degradation, enabling it to evade the host innate immune response, which provides new insights into the transmission and pathogenesis of SARS-CoV-2 infection.
Assuntos
Autofagia , COVID-19/imunologia , RNA-Polimerase RNA-Dependente de Coronavírus/fisiologia , Interferon Tipo I/biossíntese , Metiltransferases/fisiologia , Proteínas Serina-Treonina Quinases/metabolismo , RNA Helicases/fisiologia , SARS-CoV-2/fisiologia , Proteína Sequestossoma-1/metabolismo , Proteínas não Estruturais Virais/fisiologia , Proteína Beclina-1/antagonistas & inibidores , Linhagem Celular , Regulação para Baixo , Humanos , Evasão da Resposta Imune , Imunidade Inata , Imunoprecipitação , Interferon Tipo I/genética , Complexos Multiproteicos , Agregados Proteicos , Mapeamento de Interação de ProteínasRESUMO
The development of novel topoisomerase I (TOP1) inhibitors is crucial for overcoming the drawbacks and limitations of current TOP1 poisons. Here, we identified two potential TOP1 inhibitors, namely, FTY720 (a sphingosine 1-phosphate antagonist) and COH29 (a ribonucleotide reductase inhibitor), through experimental screening of known active compounds. Biological experiments verified that FTY720 and COH29 were nonintercalative TOP1 catalytic inhibitors that did not induce the formation of DNA-TOP1 covalent complexes. Molecular docking revealed that FTY720 and COH29 interacted favorably with TOP1. Molecular dynamics simulations revealed that FTY720 and COH29 could affect the catalytic domain of TOP1, thus resulting in altered DNA-binding cavity size. The alanine scanning and interaction entropy identified Arg536 as a hotspot residue. In addition, the bioinformatics analysis predicted that FTY720 and COH29 could be effective in treating malignant breast tumors. Biological experiments verified their antitumor activities using MCF-7 breast cancer cells. Their combinatory effects with TOP1 poisons were also investigated. Further, FTY720 and COH29 were found to cause less DNA damage compared with TOP1 poisons. The findings provide reliable lead compounds for the development of novel TOP1 catalytic inhibitors and offer new insights into the potential clinical applications of FTY720 and COH29 in targeting TOP1.
Assuntos
Antineoplásicos , DNA Topoisomerases Tipo I , Cloridrato de Fingolimode , Simulação de Acoplamento Molecular , Inibidores da Topoisomerase I , Humanos , Cloridrato de Fingolimode/farmacologia , Cloridrato de Fingolimode/química , Cloridrato de Fingolimode/síntese química , DNA Topoisomerases Tipo I/metabolismo , DNA Topoisomerases Tipo I/química , Inibidores da Topoisomerase I/farmacologia , Inibidores da Topoisomerase I/química , Inibidores da Topoisomerase I/síntese química , Estrutura Molecular , Relação Estrutura-Atividade , Antineoplásicos/farmacologia , Antineoplásicos/química , Antineoplásicos/síntese química , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Proliferação de Células/efeitos dos fármacos , Simulação de Dinâmica Molecular , Células MCF-7RESUMO
DNA topoisomerase I (TOP1) catalytic inhibitors are a promising class of antitumor agents. Oleanolic acid derivatives are potential TOP1 catalytic inhibitors. However, their inhibitory activity still needs to be enhanced, and the stability and hotspot residue sites of their interaction with TOP1 remain to be elucidated. Herein, a novel oleanolic acid derivative, OA4 (N-(3-(methyl(3-(orotic amido)propyl)amino)propyl)oleanolamide), was identified by rational design. Subsequently, molecular dynamics simulations were performed to explore the stability and conformational dynamics of the TOP1-OA4 complex. The molecular mechanics/generalized Born surface area method calculated the binding free energy and predicted Arg488, Ile535, and His632 to be hotspot residues. Biological experiments verified that OA4 is a nonintercalative TOP1 catalytic inhibitor. OA4 exhibits better proliferation inhibitory activity against tumor cells than normal cells. Furthermore, OA4 can induce apoptosis and effectively suppress the proliferation and migration of cancer cells. This work provides new insights for the development of novel TOP1 catalytic inhibitors.
Assuntos
Antineoplásicos , Ácido Oleanólico , Inibidores da Topoisomerase I/química , Simulação de Dinâmica Molecular , DNA Topoisomerases Tipo I/metabolismo , Antineoplásicos/farmacologia , Antineoplásicos/químicaRESUMO
Leonurus japonicus Houtt. has been traditionally used to treat many ailments. This study evaluated the activating blood circulation, anti-inflammatory, and diuretic effects of L. japonicus extract (LJ) and identified its phytochemicals. In this work, the phytochemicals in LJ were identified using liquid chromatography mass spectrometry. Rats were randomly assigned to three groups (n=8): Control group was treated with saline, while the Model group (saline) and LJ group (426â mg/kg) had induced traumatic injury. All rats were treated with once by daily oral gavage for one week. The biochemical indices and protein expression were measured. Herein, 79 constituents were identified in LJ, which were effective in elevating body weight, food consumption, water intake, and urinary excretion volume, as well as in ameliorating traumatic muscle tissues in model rats. In addition, LJ prominently decreased the contents of plasma viscosity, platelet aggregation rate, thrombin time, prothrombin time, activated partial thromboplastin time, fibrinogen, thromboxane B2 (TXB2), TXB2/6-keto-prostaglandin F1α (6-keto-PGF1α), urokinase-type plasminogen activator (u-PA), plasminogen activator inhibitor 1 (PAI-1), PAI-1/tissue-type PA (t-PA), and PAI-1/u-PA, while significantly increasing antithrombin III, 6-keto-PGF1α, and t-PA contents. Furthermore, LJ notably inhibited tumor necrosis factor alpha, interleukin 6 (IL-6), IL-8, angiotensin II, antidiuretic hormone, aldosterone, aquaporin 1 (AQP1), AQP2, and AQP3 levels, and markedly elevating IL-10 and natriuretic peptide levels. Finally, LJ markedly reduced the protein expression of AQP1, AQP2, and AQP3 compared to the model group. Collectively, LJ possessed prominent activating blood circulation, anti-inflammatory, and diuretic effects, thus supporting the clinical application of L. japonicus.
Assuntos
Medicamentos de Ervas Chinesas , Hemostasia , Leonurus , Animais , Ratos , Anti-Inflamatórios , Aquaporina 2 , Diuréticos/farmacologia , Medicamentos de Ervas Chinesas/farmacologia , Leonurus/química , Leonurus/metabolismo , Inibidor 1 de Ativador de Plasminogênio/metabolismo , Ratos Sprague-Dawley , Ativador de Plasminogênio Tecidual/metabolismo , Ativador de Plasminogênio Tipo Uroquinase/metabolismo , Hemostasia/efeitos dos fármacos , Compostos Fitoquímicos/química , Compostos Fitoquímicos/farmacologiaRESUMO
Semiliquidambar cathayensis Chang roots (SC) are traditional Chinese medicine for treating rheumatoid arthritis (RA). However, the effect and potential mechanism of SC remain unclear. This study aims to reveal the anti-RA constituents and mechanisms of SC based on network pharmacology, molecular docking, and adjuvant-induced arthritis (AIA) model rat experiment. In this work, 9â potential active constituents, including kaempferol, quercetin, naringenin, paeoniflorin, catechin, fraxin, gentianin, hesperetin, and ellagic acid 3,3',4-trimethyl ether, in SC crossed 65 target genes of RA. In addition, 28 core targets were enriched in inflammation and others, among which interleukin-17 (IL-17) and tumor necrosis factor (TNF) were the major targets. The binding of bio-constituents with IL-17 and TNF were performed using molecular docking. Rat experiment demonstrated that the extract of SC restored body weight loss, reduced arthritis score and the indices of thymus and spleen, alleviated ankle joint histopathology, decreased the levels of rheumatoid factor (RF), C-reactive protein (CRP), IL-17, TNF-α, IL-1ß, IL-6, cyclooxygenase-2 (COX-2), 5-lipoxygenase (5-LOX), and matrix metalloproteinase-2 (MMP-2), whereas elevated the levels of IL-4 and IL-10. Collectively, it was the first time to comprehensively reveal the anti-RA efficacy and mechanism of SC via suppressing the inflammatory pathway based on network pharmacology, molecular docking, and experimental verification, which provide chemical and pharmacological evidences for the clinical application of SC.
Assuntos
Artrite Reumatoide , Medicamentos de Ervas Chinesas , Ratos , Animais , Interleucina-17/uso terapêutico , Simulação de Acoplamento Molecular , Metaloproteinase 2 da Matriz , Anti-Inflamatórios/farmacologia , Farmacologia em Rede , Artrite Reumatoide/tratamento farmacológico , Artrite Reumatoide/metabolismo , Fator de Necrose Tumoral alfa , Medicamentos de Ervas Chinesas/farmacologiaRESUMO
To investigate the γ pass rate limit of plan verification equipment for volumetric modulated arc therapy (VMAT) plan verification and its sensitivity on the opening and closing errors of multi-leaf collimator (MLC), 50 cases of nasopharyngeal carcinoma VMAT plan with clockwise and counterclockwise full arcs were randomly selected. Eight kinds of MLC opening and closing errors were introduced in 10 cases of them, and 80 plans with errors were generated. Firstly, the plan verification was conducted in the form of field-by-field measurement and true composite measurement. The γ analysis with the criteria of 3% dose difference, distance to agreement of 2 mm, 10% dose threshold, and absolute dose global normalized conditions were performed for these fields. Then gradient analysis was used to investigate the sensitivity of field-by-field measurement and true composite measurement on MLC opening and closing errors, and the receiver operating characteristic curve (ROC) was used to investigate the optimal threshold of γ pass rate for identifying errors. Tolerance limits and action limits for γ pass rates were calculated using statistical process control (SPC) method for another 40 cases. The error identification ability using the tolerance limit calculated by SPC method and the universal tolerance limit (95%) were compared with using the optimal threshold of ROC. The results show that for the true composite measurement, the clockwise arc and the counterclockwise arc, the descent gradients of the γ passing rate with per millimeter MLC opening error are 10.61%, 7.62% and 6.66%, respectively, and the descent gradients with per millimeter MLC closing error are 9.75%, 7.36% and 6.37%, respectively. The optimal thresholds obtained by the ROC method are 99.35%, 97.95% and 98.25%, respectively, and the tolerance limits obtained by the SPC method are 98.98%, 97.74% and 98.62%, respectively. The tolerance limit calculated by SPC method is close to the optimal threshold of ROC, both of which could identify all errors of ±2 mm, while the universal tolerance limit can only partially identify them, indicating that the universal tolerance limit is not sensitive on some large errors. Therefore, considering the factors such as ease of use and accuracy, it is suggested to use the true composite measurement in clinical practice, and to formulate tolerance limits and action limits suitable for the actual process of the institution based on the SPC method. In conclusion, it is expected that the results of this study can provide some references for institutions to optimize the radiotherapy plan verification process, set appropriate pass rate limit, and promote the standardization of plan verification.
Assuntos
Neoplasias Nasofaríngeas , Radioterapia de Intensidade Modulada , Humanos , Tolerância Imunológica , Carcinoma Nasofaríngeo , Curva ROC , Neoplasias Nasofaríngeas/radioterapiaRESUMO
In this study, we describe a novel synthesis of galactosylated lipids by lipase catalysis. Lactitol (Lac), galactose (Gal), or N-acetyl galactosamine (GalNAc) was coupled with cholesterol (CHS) as target head groups by enzyme-catalyzed regioselective esterification to produce three kinds of lipids: CHS-1-Gal, CHS-6-Gal, or CHS-6-GalNAc1. The biological effects of galactosylated lipids carrying different constitutional isomers of the pendent sugar species were investigated. LP-1-Gal (liposomes containing 5.0 molar% of CHS-1-Gal) showed strong binding to tetrameric lectins of Ricinus communis agglutinin (RCA120) in vitro, while LP-6-Gal (liposomes containing 5.0 molar% of CHS-6-Gal) and LP-6-GalNAc (liposomes containing 5.0 molar% of CHS-6-GalNAc) did not. After intravenous injection, LP-6-GalNAc, LP-1-Gal and LP-6-Gal rapidly disappeared from the blood and accumulated rapidly in liver (up to 74.88 ± 4.11%, 58.67 ± 5.75%, and 47.66 ± 4.56% of injected dose/g organ within 4 h, respectively). This is significantly higher than the uptake of unmodified liposomes (Unmod-LP) (18.67 ± 6.07%). Pre-injection of asialofetuin significantly inhibits liver uptake of Gal-liposomes (P < 0.01), with the degree of inhibition appearing in the following order: LP-6-GalNAc (73.29%) > LP-1-Gal (67.06%) > LP-6-Gal (53.61%). More importantly, LP-6-GalNAc was preferentially taken up by hepatocytes and the uptake ratio by parenchymal cells (PC) and nonparenchymal cells (NPC) (PC/NPC ratio) was 11.03 higher than LP-1-Gal (7.32), LP-6-Gal (5.83) and Unmod-LP (2.39). We suggest that liposomes containing the novel galactosylated lipid CHS-6-GalNAc have potential as drug delivery carriers for hepatocyte-selective targeting.
Assuntos
Receptor de Asialoglicoproteína/metabolismo , Galactosamina/metabolismo , Galactose/metabolismo , Hepatócitos/metabolismo , Animais , Receptor de Asialoglicoproteína/química , Feminino , Galactosamina/química , Galactose/química , Hepatócitos/química , Lipossomos/química , Lipossomos/metabolismo , Camundongos , Camundongos Endogâmicos , Estrutura Molecular , Tamanho da Partícula , EstereoisomerismoRESUMO
Three novel monoterpenoid indole alkaloids gardflorine A (1), gardflorine B (2), and gardflorine C (3) were isolated from the leaves of Gardneria multiflora. Their structures, including absolute configurations, were established on the basis of spectroscopic methods (MS, UV, IR, 1D and 2D NMR) and circular dichroism experiments. All the compounds were evaluated for their vasorelaxant and acetylcholinesterase (AChE) inhibitory activities. Compound 1 exhibited potent vasorelaxant activity, with an EC50 value of 8.7 µM, and compounds 2 and 3 showed moderate acetylcholinesterase (AChE) inhibitory activities, with IC50 values of 26.8 and 29.2 µM, respectively.
Assuntos
Inibidores da Colinesterase/farmacologia , Loganiaceae/química , Folhas de Planta/química , Alcaloides de Triptamina e Secologanina/farmacologia , Vasodilatadores/farmacologia , Inibidores da Colinesterase/química , Dicroísmo Circular , Espectroscopia de Prótons por Ressonância Magnética , Alcaloides de Triptamina e Secologanina/química , Vasodilatadores/químicaRESUMO
OBJECTIVE: To explore the feasibility of using the bidirectional local distance based medical similarity index (MSI) to evaluate automatic segmentation on medical images. METHODS: Taking the intermediate risk clinical target volume for nasopharyngeal carcinoma manually segmented by an experience radiation oncologist as region of interest, using Atlas-based and deep-learning-based methods to obtain automatic segmentation respectively, and calculated multiple MSI and Dice similarity coefficient (DSC) between manual segmentation and automatic segmentation. Then the difference between MSI and DSC was comparatively analyzed. RESULTS: DSC values for Atlas-based and deep-learning-based automatic segmentation were 0.73 and 0.84 respectively. MSI values for them varied between 0.29~0.78 and 0.44~0.91 under different inside-outside-level. CONCLUSIONS: It is feasible to use MSI to evaluate the results of automatic segmentation. By setting the penalty coefficient, it can reflect phenomena such as under-delineation and over-delineation, and improve the sensitivity of medical image contour similarity evaluation.
Assuntos
Planejamento da Radioterapia Assistida por Computador , Estudos de ViabilidadeRESUMO
Five new quinolizidine alkaloids, including three sparteine-type alkaloids (1 - 3) and two cytisine-type alkaloids (4 and 5), along with four known ones, were isolated from the roots of Sophora flavescens. Their structures were determined by extensive spectroscopic techniques including IR, UV, NMR, and HR-ESI-MS. All the compounds were evaluated for their antibacterial activities against Staphylococcus aureus and Escherichia coli.
Assuntos
Alcaloides/farmacologia , Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Sophora/química , Staphylococcus aureus/efeitos dos fármacos , Alcaloides/química , Alcaloides/isolamento & purificação , Antibacterianos/química , Antibacterianos/isolamento & purificação , Relação Dose-Resposta a Droga , Testes de Sensibilidade Microbiana , Conformação Molecular , Relação Estrutura-AtividadeRESUMO
OBJECTIVE: To investigate the nursing care of prostate cancer (PCa) patients againstradioactive proctitisinduced byCyberKnifetreatment. METHODS: Sixty-eightPCapatients undergoingCyberKnife treatment in the observation group receivedspecialnursing care againstradioactive proctitis. The nursing measures includedthoserelevant toCyberKnife treatment, prevention ofradioactive proctitis, skin care, and discharge guidance. Meanwhile, another 54 prostate cancer patients received traditional nursing care as controls. We compared the incidence rate and severity of radioactive proctitis between the two groups of patients. RESULTS: The incidence rate of radioactive proctitiswas markedly lower in the observation group than in the control (2.9% vs 13.0%, P<0.05), but no statistically significant difference was observed in the severity of radioactive proctitis between the two groups of patients. CONCLUSIONS: The special nursing care againstCyberKnife-induced radioactiveproctitiscan significantlyreduce the incidence of radioactive proctitis andimprove the effect of CyberKnife treatment of prostate cancer, which therefore deserves wide clinical application.
Assuntos
Proctite/enfermagem , Neoplasias da Próstata/radioterapia , Lesões por Radiação/enfermagem , Radiocirurgia/efeitos adversos , Estudos de Casos e Controles , Humanos , Masculino , Proctite/etiologia , Proctite/prevenção & controle , Lesões por Radiação/prevenção & controleRESUMO
The first rotameric monoterpenoid indole alkaloids (MIAs), 1a and 1b, and two unusual dimeric MIAs, 2 and 3, with new dimerization patterns, together with their putative biosynthetic intermediates 4-7, were isolated from the roots of Gelsemium elegans. Compounds 2 and 3 represent the first natural aromatic azo- and the first urea-linked dimeric MIAs, respectively. Their structures and absolute configurations were elucidated by means of NMR spectroscopy, single-crystal X-ray diffraction, and electronic circular dichroism data analyses. The interconverting mechanism of rotamers 1a and 1b was studied by density functional theory computation. Compounds 2 and 3 showed moderate cytotoxic activity against MCF-7 and PC-12 cells, respectively. In addition, a plausible biosynthesis pathway for the new alkaloids was proposed on the basis of the coexistence of their biosynthetic precursors.
Assuntos
Medicamentos de Ervas Chinesas/isolamento & purificação , Gelsemium/química , Alcaloides de Triptamina e Secologanina/isolamento & purificação , Animais , Cristalografia por Raios X , Medicamentos de Ervas Chinesas/química , Medicamentos de Ervas Chinesas/farmacologia , Conformação Molecular , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Células PC12 , Raízes de Plantas/química , Ratos , Alcaloides de Triptamina e Secologanina/química , Alcaloides de Triptamina e Secologanina/farmacologia , Sais de Tetrazólio/farmacocinética , Tiazóis/farmacocinéticaRESUMO
A new phenylpropanoid and a new isoflavone glycoside were isolated from Shenqi Fuzheng Injection. Their structures were elucidated as (αS)-α-ethenyl-4-hydroxy-3-methoxy-benzenemethanol (1) and calycosin 7-O-[α-d-glucopyranosyl (1 â 4)]-ß-d-glucopyranoside (2) by means of spectroscopic methods including UV, IR, HR-ESI-MS, and NMR. The absolute configurations of 1 and 2 were confirmed by quantum chemical calculation and acid hydrolysis.
Assuntos
Medicamentos de Ervas Chinesas/química , Glicosídeos/isolamento & purificação , Isoflavonas/isolamento & purificação , Fenilpropionatos/isolamento & purificação , Glucosídeos , Glicosídeos/química , Isoflavonas/química , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Fenilpropionatos/químicaRESUMO
Rayleigh waves travel along the surface of a solid structure, with most of their energy focusing within a depth of one wavelength. Thus, the reflection coefficient from a surface-breaking crack is highly sensitive to the ratio between the crack depth and the wavelength. It is possible to characterize the depth of surface-breaking cracks by measuring the features in the reflected waves. However, a feature value can correspond to multiple depth-wavelength ratios, i.e., the mapping is non-univalent, which brings difficulties for crack sizing using the feature. In this work, we use finite element method (FEM) software to perform 3-D numerical analysis on the interaction between Rayleigh waves and surface-breaking slots with various 3-D geometries. Multiple features are selected based on the nearest neighbour regression analysis on a numerical dataset, ensuring that a univalent mapping relationship from the selected features to the slot depth can be established. This relationship is then experimentally used to predict the depth of real slots with different geometries, showing reasonable accuracy.
RESUMO
Structural health monitoring (SHM) requires efficient online crack detection and characterization to prevent structural failures, which mainly arise from fatigue cracks. Existing solutions for crack characterization involve analyzing sensed wave signals directly, but these approaches usually require onerous steps or many sensors to obtain sufficient and clear wave packets. An alternative strategy is a model-based inversion, which takes the full waveform into consideration and does not require analysis on a single wave packet. This approach can achieve accurate characterization with fewer sensors and simpler implementation. We propose an efficient model based on the Huygens' principle and the no-mode-conversion property of the A0 mode Lamb waves to meet the requirements of online monitoring. We then verify the proposed model-based crack imaging method through simulation and experiments on smooth and rough cracks. The proposed method is easy, cheap, and efficient, making it a desirable option for SHM tasks.
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Magnetoactive soft millirobots have made significant advances in programmable deformation, multimodal locomotion, and untethered manipulation in unreachable regions. However, the inherent limitations are manifested in the solid-phase millirobot as limited deformability and in the liquid-phase millirobot as low stiffness. Herein, we propose a ternary-state magnetoactive millirobot based on a phase transitional polymer embedded with magnetic nanoparticles. The millirobot can reversibly transit among the liquid, solid, and viscous-fluid phases through heating and cooling. The liquid-phase millirobot has elastic deformation and mobility for unimpeded navigation in a constrained space. The viscous-fluid phase millirobot shows irreversible deformation and large ductility. The solid-phase millirobot shows good shape stability and controllable locomotion. Moreover, the ternary-state magnetoactive millirobot can achieve prominent capabilities including stiffness change and shape reconfiguration through phase transition. The millirobot can perform potential functions of navigation in complex terrain, three-dimensional circuit connection, and simulated treatment in a stomach model. This magnetoactive millirobot may find new applications in flexible electronics and biomedicine.
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In the present research, Fe-based metal-organic frameworks (MIL-101(Fe)-NH2) nanoparticles were synthesized by simple solvothermal methods and used to assay Cr(â ¥). The MIL-101(Fe)-NH2 performs dual functions: the 2-aminoterephthalic acid (NH2-BDC) ligand endows a strong fluorescence emission, and the Fe metal nodes are able to facilitate the oxidation of 3,3',5,5'- tetramethylbenzidine (TMB) directly, resulting in the generation of oxidized-TMB (ox-TMB). Our research results showed that reducing agents such as ascorbic acid (AA) can collapse the structures of MIL-101(Fe)-NH2 because of the reduction of Fe3+ by AA, resulting in release of NH2-BDC. In the presence of Cr(â ¥), the fluorescence intensity of the MIL-101(Fe)-NH2 + AA system will be decreased due to the competitive reduction of Fe3+ and Cr(â ¥). Nevertheless, Cr(â ¥) can significantly accelerate the oxidation of TMB by MIL-101(Fe)-NH2 as it boosts the electron transfer rate between Fe3+ and Fe2+. Therefore, a fluorescent/colorimetric dual-mode platform was developed for the detection of Cr(â ¥) with an extensive linear range (7.5-750 µg/L and 13.3-1000 µg/L) as well as a remarkably low detection limit (0.99 µg/L and 1.98 µg/L). This MOF with the ability to release ligands not only provides inspiration for the design of new luminescent materials, but also offers a novel and reliable solution for the detection of Cr(â ¥).
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To investigate the diversity and dynamics of microorganisms in Chinese fresh beef (CFB) without acid discharge treatment during cold storage, high-throughput sequencing was employed to analyze the CFB refrigerated for 0, 3, 7, and 10 days. The results showed that the community richness of the fungi and bacteria decreased significantly. However, the diversity decreased in the early stage and increased in the later stage. At the phylum level, Ascomycota (74.1-94.1%) and Firmicutes (77.3-96.8%) were the absolutely dominant fungal and bacterial phyla. The relative abundance of both fungal and bacterial phyla displayed a trend of increasing and then decreasing. At the genus level, Candida (29.3-52.5%) and Lactococcus (19.8-59.3%) were, respectively, the dominant fungal and bacterial genera. The relative abundance of Candida showed a trend of increasing and then decreasing, while Lactococcus possessed the opposite trend. KEGG metabolic pathways analysis suggested that carbohydrate metabolism, membrane transport, and amino acid metabolism were the major metabolic pathways of bacteria. Bugbase prediction indicated the major microbial phenotype of bacteria in CFB during cold storage was Gram-positive (17.2-31.6%). Correlation analysis suggested that Lactococcus, Citrobacter, Proteus, and Rhodotorula might be the main microorganisms promoting the production of off-flavor substances in CFB. This study provides a theoretical basis for the preservation of Chinese fresh beef.
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In this study, a porous coordination network zirconium-porphyrin-based nanoparticle with oxygen vacancies (OVs) was prepared using acetic acid and benzoic acid as modulators via a simple hydrothermal method. The presence of OVs was confirmed by various characterization methods and was found to enhance oxygen uptake and activation. This resulted in the generation of more reactive peroxyl radicals (â¢O2 -) and led to an improved oxidase (OXD) mimetic activity. Additionally, it promoted 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) oxidation, with a low Km value of 0.07 mM and a high Vmax of 1.47 × 10-7 M·s-1. As aflatoxin B1 (AFB1) inhibits the Pt@PCN-222-ABTS nanozyme system, a colorimetric probe for AFB1 detection was constructed. The limit of detection (LOD) was 0.074 µg·L-1. This research presents a novel approach for designing a nanozymatic-based colorimetric method to analyze trace AFB1 residues in food.
Assuntos
Aflatoxina B1 , Colorimetria , Oxirredutases , Oxigênio , Porfirinas , Zircônio , Colorimetria/métodos , Aflatoxina B1/análise , Zircônio/química , Oxigênio/química , Porfirinas/química , Oxirredutases/metabolismo , Oxirredutases/química , Estruturas Metalorgânicas/química , Oxirredução , Limite de Detecção , Contaminação de Alimentos/análise , Nanopartículas/químicaRESUMO
Perusing metal-based redox nanozyme offers new opportunity for pollutant removal and biosensor, but ultrasound (US)-driven laccase-like nanozyme remains a significant challenge, especially in combination with defect engineering strategy. Herein, the Cu2Ov@Ce-TCPP was synthesized by doping Ce3+ on the surface of Cu2O nanocube and then coating with the porphyrin sonosensitizer. The Ce-doped porphyrin metal-structure in nanozyme was demonstrated to generate oxygen vacancy defects, which could obviously promote the laccase-like activity of Cu2Ov@Ce-TCPP nanozyme under US. XPS characterization and density functional theory (DFT) theoretical calculation revealed that the ultrasonic stimulation is beneficial to accelerate the electron transfer rate and O2 adsorption to improve catalytic activity, and Cu2Ov@Ce-TCPP nanozyme exhibits low adsorption energy and activation energy due to the presence of oxygen defect site, resulting in high laccase-like activity. The interaction between Ce atom and porphyrin structure also improved the sonocatalytic ability of the nanozyme. Meanwhile, Cu2Ov@Ce-TCPP nanozyme has been used for detecting and degrading a series of phenolic compounds. The detection adrenaline method has a linear range of 3.3-1000 µM and a detection limit as low as 0.96 µM with good reproducibility. The developed US-enhancing and recyclable laccase-like nanozyme system provides a promising strategy for the oxidation and detection of phenolic compounds.