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1.
Biochem Biophys Res Commun ; 695: 149424, 2024 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-38169186

RESUMO

Liver cancer is the fourth most lethal cancer, but the treatment options for liver cancer are usually limited. Metabolic reprogramming is a hallmark of malignancy, ensuring activated cell glycolysis and increased macromolecular precursors required for the proliferation and migration of exuberant cancer cells. MicroRNAs (miRNAs) have been reported to participate in cancer metabolic shifts mainly by directly silencing the expression of specific genes. Here, we identified miR-148a-3p as a negative regulator for glycometabolism and cell proliferation in liver cancer. miR-148a-3p directly targets the 3'UTR of transmembrane protein 54 (TMEM54), leading to the significant inhibition of lactate production, glucose consumption, intracellular ATP level and extracellular acidification rate (ECAR), as well as the repression of the proliferation and colony formation ability of liver cancer cells. miR-148a-3p expression is often down-regulated in liver cancer tissues. In addition, there was a negative correlation between the expression levels of miR-148a-3p and TMEM54 in liver cancer tissues. Moreover, the low miR-148a-3p expression levels or high TMEM54 expression levels were associated with poorer prognosis in hepatocellular carcinoma (HCC) patients. Together, these findings support that the miR-148a-3p/TMEM54 regulatory pathway regulates the glycometabolism and cell proliferation in liver cancer, which is a possible target for the diagnosis and treatment of liver cancer.


Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , MicroRNAs , Humanos , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Regulação Neoplásica da Expressão Gênica , Neoplasias Hepáticas/genética , MicroRNAs/genética , MicroRNAs/metabolismo
2.
Ann Surg Oncol ; 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-39014163

RESUMO

BACKGROUND: Lung cancer poses a global health threat necessitating early detection and precise staging for improved patient outcomes. This study focuses on developing and validating a machine learning-based risk model for early lung cancer screening and staging, using routine clinical data. METHODS: Two medical center, observational, retrospective studies were conducted, involving 2312 lung cancer patients and 653 patients with benign nodules. Machine learning techniques, including differential analysis and feature selection, were employed to identify key factors for modeling. The study focused on variables such as nodule density, carcinoembryonic antigen (CEA), age, and lifestyle habits. The Logistic Regression model was utilized for early diagnoses, and the XGBoost model was utilized for staging based on selected features. RESULTS: For early diagnoses, the Logistic Regression model achieved an area under the curve (AUC) of 0.716 (95% confidence interval [CI] 0.607-0.826), with 0.703 sensitivity and 0.654 specificity. The XGBoost model excelled in distinguishing late-stage from early-stage lung cancer, exhibiting an AUC of 0.913 (95% CI 0.862-0.963), with 0.909 sensitivity and 0.814 specificity. These findings highlight the model's potential for enhancing diagnostic accuracy and staging in lung cancer. CONCLUSION: This study introduces a novel machine learning-based risk model for early lung cancer screening and staging, leveraging routine clinical information and laboratory data. The model shows promise in enhancing accuracy, mitigating overdiagnosis, and improving patient outcomes.

3.
BMC Cancer ; 24(1): 851, 2024 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-39026211

RESUMO

BACKGROUND: Immune checkpoint inhibitors, such as anti-programmed cell death-1 (PD-1) and PD-1 ligand-1 (PD-L1) antibodies, have achieved breakthrough results in improving long-term survival rates in lung cancer. Although high levels of PD-L1 expression and tumor mutational burden have emerged as pivotal biomarkers, not all patients derive lasting benefits, and resistance to immune checkpoint blockade remains a prevalent issue. Comprehending the immunological intricacies of lung cancer is crucial for uncovering the mechanisms that govern responses and resistance to immunomodulatory treatments. This study aimed to explore the potential of peripheral immune markers in predicting treatment efficiency among lung cancer patients undergoing PD-1/PD-L1 checkpoint inhibitors. METHODS: This study enrolled 71 lung cancer patients undergoing PD-1/PD-L1 inhibitor therapy and 20 healthy controls. Immune cell subsets (CD4 + T cells, CD8 + T cells, B cells, NK cells, and NKT cells), phenotypic analysis of T cells and B cells, and PMA/Ionomycin-stimulated lymphocyte function assay were conducted. RESULTS: Lung cancer patients exhibited significant alterations in immune cell subsets, notably an increased percentage of Treg cells. Post-treatment, there were substantial increases in absolute numbers of CD3 + T cells, CD8 + T cells, and NKT cells, along with heightened HLA-DR expression on CD3 + T and CD8 + T cells. Comparison between complete remission and non-complete remission (NCR) groups showed higher Treg cell percentages and HLA-DR + CD4 + T cells in the NCR group. CONCLUSION: The study findings suggest potential predictive roles for immune cell subsets and phenotypes, particularly Treg cells, HLA-DR + CD4 + T cells, and naïve CD4 + T cells, in evaluating short-term PD-1/PD-L1 therapy efficacy for lung cancer patients. These insights offer valuable prospects for personalized treatment strategies and underscore the importance of immune profiling in lung cancer immunotherapy.


Assuntos
Antígeno B7-H1 , Inibidores de Checkpoint Imunológico , Neoplasias Pulmonares , Receptor de Morte Celular Programada 1 , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/imunologia , Masculino , Feminino , Pessoa de Meia-Idade , Inibidores de Checkpoint Imunológico/uso terapêutico , Idoso , Antígeno B7-H1/antagonistas & inibidores , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Biomarcadores Tumorais , Adulto
4.
J Org Chem ; 2024 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-38996186

RESUMO

C3-functionalized dihydroquinolinones represent a class of important biologically active compounds. Although methods for synthesizing C2/4-functionalized dihydroquinolinones have been extensively reported, research on the synthesis of C3-functionalized dihydroquinolinone is extremely rare. Herein, we report for the first time a method for C3-alkenylated dihydroquinolinones via iron(III)-catalyzed amine-release triple condensation of enaminones. These reactions exhibit broad substrate scope and offer operationally simple, low-cost catalyzed procedures in a single step. Subsequent intramolecular and intermolecular additions to the alkene moiety provide diverse C3-functionalized dihydroquinolinone derivatives.

5.
BMC Health Serv Res ; 24(1): 129, 2024 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-38263150

RESUMO

BACKGROUND: This research depicts the linkage of public leadership on public health delivery (PHD) and collaborative administration. The research is also focused to examine the effect of public leadership on public health delivery through the intervening variable of collaborative administration by using both social information processing theory and collaboration theory. METHODS: This research is based on quantitative method. Data was collected from 464 public hospital administration in the context of Pakistan. This study evaluated data using SPSS, AMOS, and PROCESS Macro. RESULTS: Public leadership has a positive profound effect on public health delivery and collaborative administration, and that collaborative administration significantly promotes public health delivery. The outcomes also exposed that public leadership has substantial influence on public health delivery through intervening collaborative administration. CONCLUSIONS: Whilst public leadership demonstrated positive outcomes on public health delivery and collaborative administration, there is a need for more rigor studies on collaborative governance leadership, collaborative ethics and collaborative norms in the public health service.


Assuntos
Liderança , Saúde Pública , Humanos , Cognição , Paquistão , Teoria Social
6.
Biomed Chromatogr ; 38(7): e5882, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38649307

RESUMO

The "schisandra-evodia" herb pair (S-E) is a herbal preparation to treat Alzheimer's disease (AD). This study aims to investigate the therapeutic efficacy and potential mechanism of S-E in AD rats, utilizing pharmacodynamic assessments and serum- and urine-based metabolomic analyses. Pharmacodynamic assessments included Morris water maze test, hematoxylin-eosin staining and immunohistochemistry experiments. The results of the study showed that the AD model was successful; the S-E significantly enhanced long-term memory and spatial learning in AD rats. Meanwhile, S-E notably ameliorated Aß25-35-induced cognitive impairment, improved hippocampal neuron morphology, decreased Aß deposition in the hippocampus and mitigated inflammatory damage. We then analyzed serum and urine samples using UPLC-MS/MS to identify potential biomarkers and metabolic pathways. Metabolomic analysis revealed alterations in 40 serum metabolites and 38 urine metabolites following S-E treatment, predominantly affecting pathways related to taurine and hypotaurine metabolism, linoleic acid metabolism, α-linolenic acid metabolism, glycerophospholipid metabolism and arachidonic acid metabolism. This study elucidates the biochemical mechanism underlying AD and the metabolic pathway influenced by S-E, laying the groundwork for future clinical applications.


Assuntos
Doença de Alzheimer , Metaboloma , Metabolômica , Ratos Sprague-Dawley , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Animais , Metabolômica/métodos , Ratos , Cromatografia Líquida de Alta Pressão/métodos , Masculino , Metaboloma/efeitos dos fármacos , Metaboloma/fisiologia , Espectrometria de Massas em Tandem/métodos , Modelos Animais de Doenças , Medicamentos de Ervas Chinesas/farmacologia , Medicamentos de Ervas Chinesas/administração & dosagem , Biomarcadores/sangue , Biomarcadores/urina , Hipocampo/metabolismo , Hipocampo/efeitos dos fármacos , Peptídeos beta-Amiloides/metabolismo
7.
Chem Biodivers ; 21(3): e202301315, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38189169

RESUMO

Thousands of years ago, humans started to use propolis because of its medicinal properties, and modern science has successfully identified several bioactive molecules within this resinous bee product. However, a natural propolis extract which has been removed the adhesive glue and preserved propolis bioactive compounds is urgently needed to maximise the therapeutic opportunities. In this study, a novel ultrafiltrate fraction from Brazilian green propolis, termed P30K, was demonstrated with anti-inflammatory properties, both in vitro and in vivo. Total flavonoids and total phenolic acids content in P30K were 244.6 mg/g and 275.8 mg/g respectively, while the IC50 value of inhibition of cyclooxygenase-2 (COX-2) was 8.30 µg/mL. The anti-inflammatory activity of P30K was furtherly corroborated in experimental models of lipopolysaccharides (LPS)-induced acute liver and lung injury. Mechanistically, integrated GC-MS and LC-MS based serum metabolomics analysis revealed that P30K modulated citrate cycle (TCA), pyruvate, glyoxylate and dicarboxylate metabolism pathways to inhibit secretion of pro-inflammatory cytokines. Results of network pharmacology and molecular docking suggested that P30K targeted catechol-O-methyltransferases (COMT), 11ß-hydroxysteroid dehydrogenases (HSD11B1), and monoamine oxidases (MAOA and MAOB) to promote cellular metabolomic rewiring. Collectively, our work reveals P30K as an efficient therapeutic agent against inflammatory conditions and its efficacy is related to metabolic rewiring.


Assuntos
Própole , Humanos , Própole/farmacologia , Simulação de Acoplamento Molecular , Flavonoides/farmacologia , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico , Brasil
8.
J Am Chem Soc ; 145(5): 2800-2805, 2023 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-36705987

RESUMO

Freshman chemistry teaches that Fe3+ and Cu2+ ions are stable in water solutions, but their reduced forms, Fe2+ and Cu+, cannot exist in water as the major oxidation state due to the fast oxidation by O2 and/or disproportionation. Contrary to these well-known facts, significant fractions of dissolved Fe and Cu species exist in their reduced oxidation states in atmospheric water such as deliquesced aerosols, clouds, and fog droplets. Current knowledge attributes these phenomena to the stabilization of the lower oxidation states by the complexation of ligands and the various photochemical or thermal pathways that can reduce the higher oxidation states. In this study, by spraying the water solutions of transition metal ions into microdroplets, we show the results of the spontaneous reduction of ligated Fe(III) and Cu(II) species into Fe(II) and Cu(I) species, presenting a previously unknown source of reduced transition metal ions in atmospheric water. It is the spontaneously generated electrons in water microdroplets that are responsible for the reduction. Control experiments in the atmosphere and in a glove box filled with precisely controlled gaseous contents reveal that O2, CO2, and NO2 are the major competitors for the electrons, forming O2-, HCO2-, and NO2-, respectively. Taking these findings together, we opine that microdroplet chemistry might play significant but previously underestimated roles in atmospheric redox chemistry.

9.
J Am Chem Soc ; 145(4): 2647-2652, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36668682

RESUMO

Recent advances in microdroplet chemistry have shown that chemical reactions in water microdroplets can be accelerated by several orders of magnitude compared to the same reactions in bulk water. Among the large plethora of unique properties of microdroplets, an especially intriguing one is the strong reducing power that can be sometimes as high as alkali metals as a result of the spontaneously generated electrons. In this study, we design a catalyst-free strategy that takes advantage of the reducing ability of water microdroplets to reduce a certain molecule, and the reduced form of that molecule can convert CO2 into value-added products. By spraying the water solution of C6F5I into microdroplets, an exotic and fragile radical anion, C6F5I•-, is observed, where the excess electron counter-intuitively locates on the σ* antibonding orbital of the C-I bond as evidenced by anion photoelectron spectroscopy. This electron weakens the C-I bond and causes the formation of C6F5-, and the latter attacks the carbon atom on CO2, forming the pentafluorobenzoate product, C6F5CO2-. This study provides a good example of strategically making use of the spontaneous properties of water microdroplets, and we anticipate that microdroplet chemistry will be a green avenue rich in new opportunities in CO2 utilization.

10.
J Am Chem Soc ; 145(39): 21207-21212, 2023 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-37724917

RESUMO

The use of external electric fields as green and efficient catalysts in synthetic chemistry has recently received significant attention for their ability to deliver remarkable control of reaction selectivity and acceleration of reaction rates. Technically, methods of generating high electric fields in the range of 1-10 V/nm are limited, as in-vacuo techniques have obvious scalability issues. The spontaneous high fields at various interfaces promise to solve this problem. In this study, we take advantage of the spontaneous high electric field at the air-water interface of sprayed water microdroplets in the reactions of several halogen bond systems: Nu:--X-X, where Nu: is pyridine or quinuclidine and X is bromine or iodine. The field facilitates ultrafast electron transfer from Nu:, yielding a Nu-X covalent bond and causing the X-X bond to cleave. This reaction occurs in microseconds in microdroplets but takes days to weeks in bulk solution. Density functional theory calculations predict that the reaction becomes barrier-free in the presence of oriented external electric fields, supporting the notion that the electric fields in the water droplets are responsible for the catalysis. We anticipate that microdroplet chemistry will be an avenue rich in opportunities in the reactions facilitated by high electric fields and provides an alternative way to tackle the scalability problem.

11.
J Am Chem Soc ; 145(48): 26003-26008, 2023 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-38011046

RESUMO

Even though it is still an emerging field, the application of a high external electric field (EEF) as a green and efficient catalyst in synthetic chemistry has recently received significant attention for the ability to deliver remarkable control of reaction selectivity and acceleration of reaction rates. Here, we extend the application of the EEF to Menshutkin reactions by taking advantage of the spontaneous high electric field at the air-water interfaces of sprayed water microdroplets. Experimentally, a series of Menshutkin reactions were accelerated by 7 orders of magnitude. Theoretically, both density functional theory calculations and ab initio molecular dynamics simulations predict that the reaction barrier decreases significantly in the presence of oriented external electric fields, thereby supporting the notion that the electric fields in the water droplets are responsible for the catalysis. In addition, the ordered solvent and reactant molecules oriented by the electric field alleviate the steric effect of solvents and increase the successful collision rates, thus facilitating faster nucleophilic attack. The success of Menshutkin reactions in this study showcases the great potential of microdroplet chemistry for green synthesis.

12.
Exp Dermatol ; 32(4): 368-378, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36401800

RESUMO

The infiltration of neutrophils in the epidermis and the release of neutrophil extracellular traps (NETs) are important events in the pathogenesis of psoriasis, but the regulatory roles and internal mechanism of NETs in psoriasis are largely unknown. Here, we demonstrate that NETs can activate the absent-in-melanoma-2 (AIM2) inflammasome in keratinocytes through the p38-MAPK signalling pathway, and targeting NETs with CI-amidine in vivo reduces AIM2 expression and ameliorates imiquimod-induced psoriasis-like phenotype in mice. Notably, NETs-activated AIM2 in keratinocytes not only promotes IL-1ß production through the classical inflammasome pathway but also promotes IFN-γ production via X-linked inhibitor of apoptosis protein (XIAP), thereby mediating the immune responses of keratinocytes. In conclusion, our study demonstrates that the NETs-AIM2 axis exerts multiple pro-inflammatory effects on keratinocytes and may serve as a potential target for psoriasis therapy.


Assuntos
Armadilhas Extracelulares , Melanoma , Psoríase , Animais , Camundongos , Armadilhas Extracelulares/metabolismo , Inflamassomos/metabolismo , Proteínas Inibidoras de Apoptose Ligadas ao Cromossomo X/metabolismo , Proteínas Inibidoras de Apoptose Ligadas ao Cromossomo X/farmacologia , Queratinócitos/metabolismo , Psoríase/metabolismo , Inflamação/metabolismo , Melanoma/metabolismo , Proteínas de Ligação a DNA
13.
Phys Chem Chem Phys ; 25(20): 13864-13876, 2023 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-37183450

RESUMO

Recently, novel 2D InGeTe3 has been successfully synthesized and attracted attention due to its excellent properties. In this study, we investigated the mechanical properties and transport behavior of InGeX3 (X = S, Se and Te) monolayers using density functional theory (DFT) and machine learning (ML). The key physical parameters related to mechanical properties, including Poisson's ratio, elastic modulus, tensile strength and critical strain, were revealed. Using a ML method to train DFT data, we developed a neuroevolution-potential (NEP) to successfully predict the mechanical properties and lattice thermal conductivity. The fracture behavior predicted using NEP-based MD simulations in a large supercell containing 20 000 atoms could be verified using DFT. Due to the effects of size, these predicted physical parameters have a slight difference between DFT and ML methods. At 300 K, these monolayers exhibited a low thermal conductivity with the values of 13.27 ± 0.24 W m-1 K-1 for InGeS3, 7.68 ± 0.30 W m-1 K-1 for InGeSe3, and 3.88 ± 0.09 W m-1 K-1 for InGeTe3, respectively. The Boltzmann transport equation (BTE) including all electron-phonon interactions was used to accurately predict the electron mobility. Compared with InGeS3 and InGeSe3, the InGeTe3 monolayer showed flexible mechanical behavior, low thermal conductivity and high mobility.

14.
J Phys Chem A ; 127(12): 2805-2809, 2023 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-36939334

RESUMO

Microdroplet chemistry has been an emerging new field for its large plethora of unique properties, among which an especially intriguing one is the strong oxidizing and reducing powers. The hydroxide ion in water microdroplets is considered to split into a hydroxyl radical and an electron at the air-water interface, and the former is responsible for the oxidizing capability while the latter is responsible for the reducing power, making a unity of opposites. However, to date there are only two examples showing that oxidation and reduction occur simultaneously to the same substrates, which might be a result of the redox properties of the substrate per se. In this study, we carefully chose a group of ο-quinone compounds as the substrates in water microdroplets and discovered that they can be both oxidized by the hydroxyl radical and reduced by the electron. These results keep pushing the limit of the unique redox properties of microdroplet chemistry.

15.
Zhongguo Zhong Yao Za Zhi ; 48(7): 1731-1738, 2023 Apr.
Artigo em Zh | MEDLINE | ID: mdl-37282947

RESUMO

Diabetic ulcer(DU) is one of the common complications of diabetes often occurring in the peripheral blood vessels of lower limbs or feet with a certain degree of damage. It has high morbidity and mortality, a long treatment cycle, and high cost. DU is often clinically manifested as skin ulcers or infections in the lower limbs or feet. In severe cases, it can ulcerate to the surface of tendons, bones or joint capsules, and even bone marrow. Without timely and correct treatment, most of the patients will have ulceration and blackening of the extremities. These patients will not be able to preserve the affected limbs through conservative treatment, and amputation must be performed. The etiology and pathogenesis of DU patients with the above condition are complex, which involves blood circulation interruption of DU wound, poor nutrition supply, and failure in discharge of metabolic waste. Relevant studies have also confirmed that promoting DU wound angiogenesis and restoring blood supply can effectively delay the occurrence and development of wound ulcers and provide nutritional support for wound healing, which is of great significance in the treatment of DU. There are many factors related to angiogenesis, including pro-angiogenic factors and anti-angiogenic factors. The dynamic balance between them plays a key role in angiogenesis. Meanwhile, previous studies have also confirmed that traditional Chinese medicine can enhance pro-angiogenic factors and down-regulate anti-angiogenic factors to promote angiogenesis. In addition, many experts and scholars have proposed that traditional Chinese medicine regulation of DU wound angiogenesis in the treatment of DU has broad prospects. Therefore, by consulting a large number of studies available, this paper expounded on the role of angiogenesis in DU wound and summarized the research advance in traditional Chinese medicine intervention in promoting the expression of angiogenic factors [vascular endothelial growth factor(VEGF), fibroblast growth factor(FGF), and angiopoietin(Ang)] which played a major role in promoting wound angiogenesis in the treatment of DU to provide ideas for further research and new methods for clinical treatment of DU.


Assuntos
Complicações do Diabetes , Diabetes Mellitus , Humanos , Medicina Tradicional Chinesa , Úlcera , Fator A de Crescimento do Endotélio Vascular/metabolismo , Complicações do Diabetes/tratamento farmacológico , Cicatrização/fisiologia
16.
Zhongguo Zhong Yao Za Zhi ; 48(7): 1724-1730, 2023 Apr.
Artigo em Zh | MEDLINE | ID: mdl-37282946

RESUMO

Diabetic ulcer(DU) is a chronic and refractory ulcer which often occurs in the foot or lower limbs. It is a diabetic complication with high morbidity and mortality. The pathogenesis of DU is complex, and the therapies(such as debridement, flap transplantation, and application of antibiotics) are also complex and have long cycles. DU patients suffer from great economic and psychological pressure while enduring pain. Therefore, it is particularly important to promote rapid wound healing, reduce disability and mortality, protect limb function, and improve the quality of life of DU patients. By reviewing the relevant literatures, we have found that autophagy can remove DU wound pathogens, reduce wound inflammation, and accelerate ulcer wound healing and tissue repair. The main autophagy-related factors microtubule-binding light chain protein 3(LC3), autophagy-specific gene Beclin-1, and ubiquitin-binding protein p62 mediate autophagy. The traditional Chinese medicine(TCM) treatment of DU mitigates clinical symptoms, accelerates ulcer wound healing, reduces ulcer recurrence, and delays further deterioration of DU. Furthermore, under the guidance of syndrome differentiation and treatment and the overall concept, TCM treatment harmonizes yin and yang, ameliorates TCM syndrome, and treats underlying diseases, thereby curing DU from the root. Therefore, this article reviews the role of autophagy and major related factors LC3, Beclin-1, and p62 in the healing of DU wounds and the intervention of TCM, aiming to provide reference for the clinical treatment of DU wounds and subsequent in-depth studies.


Assuntos
Complicações do Diabetes , Diabetes Mellitus , Pé Diabético , Humanos , Úlcera/terapia , Medicina Tradicional Chinesa , Proteína Beclina-1 , Qualidade de Vida , Cicatrização , Autofagia , Pé Diabético/tratamento farmacológico , Diabetes Mellitus/tratamento farmacológico , Diabetes Mellitus/genética
17.
J Am Chem Soc ; 144(35): 16184-16190, 2022 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-35960958

RESUMO

Oxidative C-H/N-H cross-coupling has emerged as an atom-economical method for the construction of C-N bonds. Conventional oxidative C-H/N-H coupling requires at least one of the following: high temperatures, strong oxidizers, transition metal catalysts, organic solvents, light, and electrochemical cells. In this study, by merely spraying the water solutions of the substrates into microdroplets at room temperature, we show a series of oxidative C-H/N-H coupling products that are strikingly produced in a spontaneous and ultrafast manner. The reactions are accelerated by six orders of magnitude compared to the same reactions in the bulk. It has been previously proposed by fluorescence microscopy and theory that the spontaneously generated electric field at the microdroplets peripheries can be in the ∼109 V/m range. Based on mass spectrometric analysis of key radical intermediates, we opine that the ultrahigh electric field catalytically oxidizes the substrates by removing an electron, which further promotes C/N coupling. Taken together, we anticipate that microdroplet chemistry will be an avenue rich in green opportunities of constructing C-heteroatom bonds.


Assuntos
Elementos de Transição , Água , Catálise , Oxirredução , Estresse Oxidativo , Elementos de Transição/química
18.
J Am Chem Soc ; 144(8): 3510-3516, 2022 03 02.
Artigo em Inglês | MEDLINE | ID: mdl-35167288

RESUMO

Water serves as an inert environment for the dispersion and application of many kinds of herbicides. Viologen compounds, a type of widely used but highly toxic herbicide, are stable in bulk water, whose half-life can be up to 23 weeks in natural water, imposing a severe health risk to mammals. In this study, we present the striking results of the spontaneous and ultrafast reduction-induced degradation of three viologen compounds in water microdroplets and provide the concentration, time, temperature dependence, mechanism, and scale-up of the reactions. We postulate that the electrons existing at the air-water interface of the microdroplets due to the unique redox potential therein initiate the reduction, from which further degradation occurs. The host-guest complexation between cucurbit[7]uril and viologens only slightly changes the redox potential of viologens in the bulk but completely inhibits the reactions in microdroplets, adding to the uniqueness of the redox potentials at the air-water interfaces of microdroplets. Taken together, microdroplets might have been functioning as naturally occurring ubiquitous tiny electrochemical cells for a plethora of unique redox reactions that were thought to be impossible in the bulk water.


Assuntos
Viologênios , Água , Animais , Mamíferos , Oxirredução , Temperatura , Viologênios/química , Água/química
19.
J Am Chem Soc ; 144(48): 22302-22308, 2022 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-36418024

RESUMO

The multiphase oxidation of SO2 to sulfate in aerosol particles is a key process in atmospheric chemistry. However, there is a large gap between the observed and simulated sulfate concentrations during severe haze events. To fill in the gaps in understanding SO2 oxidation chemistry, a combination of experiments and theoretical calculations provided evidence for the direct, spin-forbidden excitation of SO2 to its triplet states using UVA photons at an air-water interface, followed by reactions with water and O2 that facilitate the rapid formation of sulfate. The estimated reaction energy for the whole process, 3SO2 + H2O + 1/2O2 → HSO4- + H+ (298 K, 1 M), was ΔGr = -107.8 kcal·mol-1. Moreover, calculations revealed that this was a multistep reaction involving submerged, small energy barriers (∼10 kcal·mol-1). These results indicate that photochemical oxidation of SO2 at the air-water interface with solar actinic light may be an important unaccounted source of sulfate aerosols under polluted haze conditions.

20.
Anal Chem ; 94(24): 8555-8560, 2022 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-35666646

RESUMO

The development of efficient, low-cost, easy-to-use ambient ionization methods has been a major goal of modern mass spectrometry. In this Letter, we present a gas-free, voltage-free, economic, and safe desorption ionization method using the plasma generated by a radioactive element, americium-241, scavenged from smoke detectors that equip almost every household. No other energy sources, such as laser, discharge, fast-moving carrier gas, solvent droplet, ultrasound, or heat are needed. We name this new method as americium-241 desorption ionization (AmDI). AmDI is tested for the detection of more than 20 volatile and nonvolatile chemicals under different sampling conditions, and the detection limit can be in the range of tens of picograms for some analytes. Mechanistically, we provide evidence that the α particles emitted from radioactive decay ionize ambient air, and the resulting plasma further energizes and ionizes the surface analytes for mass spectrometry detection. We anticipate wide applications of AmDI in mass spectrometric sampling in the near future because of the plethora of merits.


Assuntos
Lasers , Fumaça , Espectrometria de Massas/métodos
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