Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.711
Filtrar
1.
Cell Prolif ; 53(4): e12786, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32301195

RESUMO

OBJECTIVES: Photodynamic therapy (PDT) is a novel non-invasive therapeutic method, which has been widely applied for the treatment of human oral cancers. However, the problems of undesirable singlet oxygen (1 O2 ) quantum yields and long-term phototoxicity were inevitable during the application of traditional photosensitizers. Therefore, it is necessary to explore novel photosensitizers for the improvement of therapeutic effects. In our study, the sulphur-doped carbon dots (S-CDs) of high yield of singlet oxygen (1 O2 ) were synthesized as a nano-photosensitizer for OSCC to improve the PDT efficacy in clinical practice. MATERIALS AND METHODS: After synthesis of the novel S-CDs, the size, morphologic characteristics, surface potential and yield of singlet oxygen (1 O2 ) were determined. In vitro study was performed to compare the therapeutic effect as well as the biocompatibility of the novel S-CDs to those of 5-ALA. Besides, possible mechanism of action was illustrated. RESULTS: After synthesis of the novel S-CDs, the size, morphologic characteristics, surface potential and yield of singlet oxygen (1 O2 ) were determined. In vitro study was performed to compare the therapeutic effect as well as the biocompatibility of the novel S-CDs to those of 5-ALA. Besides, possible mechanism of action was illustrated. CONCLUSIONS: These data from the in vitro study demonstrated the promising safety profile of the low dose (nmol/L) S-CDs, which indicated the novel S-CDs could be used as a promising photodynamic agent for oral cancer therapy.


Assuntos
Carbono/farmacologia , Carcinoma de Células Escamosas/tratamento farmacológico , Neoplasias Bucais/tratamento farmacológico , Fármacos Fotossensibilizantes/farmacologia , Enxofre/farmacologia , Apoptose/efeitos dos fármacos , Carbono/química , Carcinoma de Células Escamosas/patologia , Linhagem Celular Tumoral , Humanos , Modelos Moleculares , Neoplasias Bucais/patologia , Nanopartículas/química , Nanopartículas/ultraestrutura , Fotoquimioterapia , Fármacos Fotossensibilizantes/química , Enxofre/química
2.
Ecotoxicol Environ Saf ; 191: 110242, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-32004945

RESUMO

A novel green approach was utilized to fabricate sulfur nanoparticles (SNPs) with the aid of Ocimum basilicum leaves extract. The effective formation of the synthesized SNPs was examined and approved using UV-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) spectroscopy. The average particle size was 23 nm with spherical shape and crystalline in nature. In the pot experiment, the synthesized SNPs were applied with different concentrations (12.5, 25, 50, 100 and 200 µM) as pre-soaking to Helianthus annuus seeds and irrigated with 100 mM MnSO4. As a result of manganese (Mn) exposure, the harvested 14-day sunflower seedlings showed a significant decline in the growth parameters (shoot length, leaf area and the relative water content of both shoot and root), photosynthetic pigments, mineral content (N, P, K, Ca, and Mg), and protein content compared to the control. The root length, electrolyte leakage, Na and Mn levels, metabolites content (amino acids, protein, glycine betaine, proline, and cysteine) were greatly raised as affected by Mn stress. Mn toxicity reduction using SNPs was demonstrated, as the medium doses enhanced seedlings growth, photosynthetic pigments, and mineral nutrients. Application of SNPs decreased Mn uptake and enhanced S metabolism through increasing cysteine level. Likewise, SNPs elevated seedlings water content and eliminated physiological drought via increasing osmolytes such as amino acids and proline. It can be concluded that green-synthesized SNPs had the potential to limit the deleterious effects of Mn stress.


Assuntos
Helianthus , Manganês/toxicidade , Nanopartículas/química , Ocimum basilicum/química , Enxofre/farmacologia , Química Verde , Helianthus/efeitos dos fármacos , Helianthus/crescimento & desenvolvimento , Tamanho da Partícula , Fotossíntese/efeitos dos fármacos , Extratos Vegetais/química , Folhas de Planta/química , Prolina/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Enxofre/química , Água/metabolismo
3.
Food Chem ; 317: 126457, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32106009

RESUMO

In this work, a novel, selective and sensitive fluorescent probe (sulfur doped graphene quantum dots, SGQDs) was designed for real-time detection of quercetin in red wine samples. SGQDs were synthesized by pyrolyzing citric acid (CA) and 3-Mercaptopropionic acid (MPA) and characterized through advanced techniques. It was observed that fluorescence intensity of SGQDs could be substantially quenched by the addition of quercetin through inner filter effect (IFE) mechanism. Additionally, a visual color change (colorless to light yellow) was also noticed after addition of quercetin into a solution of SGQDs. The change in SGQDs fluorescence intensity with varying quercetin content revealed good linearity in the 0-50.0 µM range with regression coefficient of 0.9943 and a lowest detection limit of 0.006 µg/mL. To authenticate the real-time application of SGQDs as a potential fluorescent probe, red wine samples having different quercetin concentrations were used for quantitative analysis, after the optimization of several analytical parameters.


Assuntos
Corantes Fluorescentes/química , Pontos Quânticos/química , Quercetina/análise , Enxofre/química , Ácido 3-Mercaptopropiônico/química , Ácido Cítrico/química , Cor , Flavonoides/química , Fluorescência , Análise de Alimentos/métodos , Grafite/química , Concentração de Íons de Hidrogênio , Limite de Detecção , Solventes/química , Espectrometria de Fluorescência/métodos , Vinho/análise
4.
J Phys Chem Lett ; 11(4): 1215-1221, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-31978303

RESUMO

Site-selective dissociation induced by core photoexcitation of biomolecules is of key importance for the understanding of radiation damage processes and dynamics and for its promising use as "chemical scissors" in various applications. However, identifying products of site-selective dissociation in large molecules is challenging at the carbon, nitrogen, and oxygen edges because of the high recurrence of these atoms and related chemical groups. In this paper, we present the observation of site-selective dissociation at the sulfur L-edge in the gas-phase peptide methionine enkephalin, which contains only a single sulfur atom. Near-edge X-ray absorption mass spectrometry has revealed that the resonant S 2p → σ*C-S excitation of the sulfur contained in the methionine side chain leads to site-selective dissociation, which is not the case after core ionization above the sulfur L-edge. The prospects of such results for the study of charge dynamics in biomolecular systems are discussed.


Assuntos
Gases/química , Peptídeos/química , Enxofre/química , Espectroscopia por Absorção de Raios X , Encefalinas/química , Metionina/química , Prótons , Teoria Quântica
5.
Phytochemistry ; 170: 112213, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31786408

RESUMO

Clutia lanceolata Forssk. (C. lanceolata) is a medicinal plant native to sub-Saharan Africa and the Arabian Peninsula. Phytochemical investigation of the aerial parts of C. lanceolata yielded twenty-one coumarins including methylthio and methylsulfinyl-coumarins. Thirteen of these compounds are reported here for the first time, named as cluteolin A to M. The remaining eight compounds are known but have not been associated previously with C. lanceolata. The structures of the undescribed compounds were elucidated from their 2D NMR and MS spectra. Single crystal X-ray analyses confirmed the structures of eleven compounds. As, in Saudi Arabian tradition, C. lanceolata has been reported to have anti-diabetic and anti-fungal properties, the coumarins were examined for their biological activity. Seven compounds strongly enhanced the glucose-triggered release of insulin by murine pancreatic islets, with two compounds showing more than two-fold enhancement of insulin secretion, compared with the standard drug glimepiride.


Assuntos
Cumarínicos/farmacologia , Euphorbiaceae/química , Secreção de Insulina/efeitos dos fármacos , Insulina/metabolismo , Compostos Fitoquímicos/farmacologia , Enxofre/farmacologia , Animais , Cumarínicos/química , Cumarínicos/isolamento & purificação , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Compostos Fitoquímicos/química , Compostos Fitoquímicos/isolamento & purificação , Arábia Saudita , Enxofre/química , Enxofre/isolamento & purificação
6.
J Agric Food Chem ; 68(1): 250-257, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31823602

RESUMO

Cysteine is a commercially important sulfur-containing amino acid widely used as a supplement in the agricultural and food industries. It is extremely desirable to achieve a high sulfur conversion rate in the fermentation-based cysteine production. Here, the metabolic engineering of Escherichia coli was performed to enhance the sulfur conversion rate in cysteine biosynthesis. Accordingly, the reduction of sulfur loss by the regulator decR and its yhaOM operons were deleted. serACB was integrated into chromosome with constitutive promoter to coordinately increase sulfur utilization. The sulfur assimilation pathways and sulfur transcriptional regulator cysB were overexpressed to regulate sulfur metabolism and enhance sulfur conversion significantly. After the process optimization in fed-batch fermentation, LH16 [SLH02 ΔyhaM Ptrc1-serACB-cysM-nrdH-(pLH03, pTrc99a-cysB)] produced 7.5 g/L of cysteine with a sulfur conversion rate of 90.11%. These results indicate that cysteine production by LH16 is a valuable process in the agricultural and food industries.


Assuntos
Cisteína/biossíntese , Escherichia coli/genética , Escherichia coli/metabolismo , Enxofre/metabolismo , Cisteína/química , Escherichia coli/química , Fermentação , Cinética , Engenharia Metabólica , Óperon , Enxofre/química
7.
Food Chem ; 308: 125590, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-31644970

RESUMO

A novel fluorescent nanoprobe was for the first time developed for the efficient detection of ferrocyanide ions ([Fe(CN)6]4-) based on nitrogen (N), sulfur (S) and chlorine (Cl) co-doped carbon nanoparticles (N,S,Cl-CNPs). The N,S,Cl-CNPs were fabricated through a simple and ultrafast acid-base neutralization method. The sensing mechanism was based on the quenching effect of [Fe(CN)6]4- on the fluorescence emission of N,S,Cl-CNPs via dynamic interaction. The N,S,Cl-CNPs were found to show high selectivity and sensitivity towards [Fe(CN)6]4- detection with two good linear relationships were achieved in the concentration ranges of 0.01-1.0 µg/mL and 1.0-50.0 µg/mL, respectively, and the detection limits are as low as 3.3 and 21.8 ng/mL, respectively. The proposed fluorescence method was successfully applied for [Fe(CN)6]4- analyses in food samples with high accuracy. The results of this study indicate the great application prospects of N,S,Cl-CNPs for [Fe(CN)6]4- detection in complex food matrix.


Assuntos
Carbono/química , Ferrocianetos/análise , Nanopartículas , Cloro/química , Ferrocianetos/química , Fluorescência , Análise de Alimentos , Limite de Detecção , Nitrogênio/química , Espectrometria de Fluorescência/métodos , Enxofre/química
8.
J Pharm Biomed Anal ; 177: 112852, 2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31499432

RESUMO

The effect of insertion of SH and S-protected groups on the binding and mucoadhesion properties of quaternary ammonium-chitosans and their nanoparticulate forms has been investigated by NMR spectroscopy. Diclofenac sodium salt has been assumed as low molecular weight probe to detect the different binding behaviour of polymeric materials; mucin from bovine submaxillary glands was selected as the model protein for differentiating their mucoadhesion. NMR proton selective relaxation rates of the probe molecule were remarkably sensitive to the presence of very low amounts of sulfurated moieties. Impact of supramolecular aggregation in nanostructured species was demonstrated as well as the relevance of S-protection.


Assuntos
Diclofenaco/administração & dosagem , Portadores de Fármacos/química , Membrana Mucosa/metabolismo , Nanopartículas/química , Adesividade , Animais , Bovinos , Quitosana/química , Quitosana/metabolismo , Portadores de Fármacos/metabolismo , Peso Molecular , Mucinas/metabolismo , Nanopartículas/metabolismo , Espectroscopia de Prótons por Ressonância Magnética , Compostos de Amônio Quaternário/química , Compostos de Amônio Quaternário/metabolismo , Enxofre/química
9.
Spectrochim Acta A Mol Biomol Spectrosc ; 224: 117444, 2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31394388

RESUMO

The application of fluorescent carbon dots in bio-imaging has huge positive significance in the field of biomedicine. By taking this advantage, herein we prepared nitrogen, sulfur and iodine doped carbon dots (N,S,I-CDs) by a facile hydrothermal reaction using C3N3S3, potassium iodate (KIO3) and ethylenediamine (EDA), and the obtained N,S,I-CDs show bright blue fluorescence with a high fluorescence quantum yield of about 32.4%. The prepared N, S, I-CDs could interact with the folic acid (FA) with high selectivity, lead to development of a high sensitive method for the FA detection from 0.1 to 175 µM wide linear range with a detection limit of 84 nM (S/N = 3) and also applied them in U-2 OS cells imaging. Moreover, this sensor possessed a good sensitivity, linearity and reversibility in the temperature range of 10-80 °C, and successfully applied for the temperature sensing in cell HT-29 samples. This investigation illustrates that as-prepared N, S, I-CDs probe may have great potential as a high-performance platform for the accurate recognition of temperature in cells and could provide a new tool for the detection of FA in cells.


Assuntos
Técnicas Biossensoriais/métodos , Técnicas Citológicas/métodos , Ácido Fólico/análise , Pontos Quânticos/química , Linhagem Celular Tumoral , Transferência Ressonante de Energia de Fluorescência/métodos , Humanos , Iodo/química , Nitrogênio/química , Enxofre/química , Temperatura
10.
Mater Sci Eng C Mater Biol Appl ; 107: 110225, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31761201

RESUMO

Role of sulfur (S) and nitrogen (N) groups in promoting cell adhesion or commonly known as biocompatibility, is well established, but their role in reducing bacterial attachment and growth is less explored or not well-understood. Natural sulfur-based compounds, i.e. sulfide, sulfoxide and sulfinic groups, have shown to inhibit bacterial adhesion and biofilm formation. Hence, we mimicked these surfaces by plasma polymerizing thiophene (ppT) and air-plasma treating this ppT to achieve coatings with S of similar oxidation states as natural compounds (ppT-air). In addition, the effects of these N and S groups from ppT-air were also compared with the biocompatible amine-amide from n-heptylamine plasma polymer. Crystal violet assay and live and dead fluorescence staining of E. coli and S. aureus showed that all the N and S coated surfaces generated, including ppHA, ppT and ppT-air, produced similarly potent, growth reduction of both bacteria by approximately 65% at 72 h compared to untreated glass control. The ability of osteogenic differentiation in Wharton's jelly mesenchymal stem cells (WJ-MSCs) were also used to test the cell biocompatibility of these surfaces. Alkaline phosphatase assay and scanning electron microscopy imaging of these WJ-MSCs growths indicated that ppHA, and ppT-air were cell-friendly surfaces, with ppHA showing the highest osteogenic activity. In summary, the N and S containing surfaces could reduce bacteria growth while promoting mammalian cell growth, thus serve as potential candidate surfaces to be explored further for biomaterial applications.


Assuntos
Materiais Biocompatíveis/química , Nitrogênio/química , Polímeros/química , Enxofre/química , Materiais Biocompatíveis/farmacologia , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Humanos , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Osteogênese/efeitos dos fármacos , Gases em Plasma/química , Polímeros/farmacologia , Propriedades de Superfície , Geleia de Wharton/citologia
11.
J Phys Chem A ; 123(51): 10862-10867, 2019 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-31790228

RESUMO

Sulfur-substituted analogues of thymine are of three types depending on the position of sulfur substitution: 2-thiothymine (2tThy), 4-thothymine (4tThy), and 2,4-dithiothymine (dtThy). These molecules, on photoexcitation, are known to form in their triplet state with near unity yield. Consequently, they are able to photosensitize ground state molecular oxygen to singlet oxygen, a property which makes them potential drugs for photodynamic therapy (PDT). The singlet oxygen yield is directly correlated with the triplet lifetime of the thiothymine, which in turn is governed by its triplet decay dynamics. In this work, the dependence of the triplet decay dynamics on the position of sulfur substitution is investigated by comparatively studying all three thiothymines. The topology of the triplet potential energy surface and decay mechanism of 2tThy is found to be distinctly different from 4tThy and dtThy. The fundamental reason for this is the different electronic natures of the two C═X (X = O, S) moieties in each molecule, one of which is conjugated with a C═C bond, while the other is not. Further, it is shown that the triplet lifetime of 2tThy can be increased by manipulating the energetic ordering of its molecular orbitals with unobtrusive substitutions, thus making it a better candidate for a PDT drug.


Assuntos
Teoria Quântica , Enxofre/química , Timina/química , Estrutura Molecular , Fotoquimioterapia , Timina/análogos & derivados
12.
Isotopes Environ Health Stud ; 55(6): 607-629, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31711301

RESUMO

The chance of apparent isotope anomalies either in closed systems at equilibrium or during Rayleigh processes is investigated. The term 'apparent' is chosen to highlight that only mass-dependent fractionation (MDF) processes are considered. A goal is finding analytical expressions that could be used for dealing with the complexity of real systems. For example, the formula for calculating the isotopic fractionation in systems with any desired number of phases involved is identified. Terrestrial samples could exhibit artificially low MIF signatures because Δ is not invariant with the choice of the reference material. An alternative parameter Δ* only depending on ß is therefore introduced. The potential transfer of sample points in a three-isotope plot to parallel lines during reversible processes is also investigated. Larger apparent anomalies are expected in systems lacking an infinite reservoir and for large enrichment factors. Pyrite is stable beyond the conditions for a reducing environment and MIF signatures from Archaean sediments could be compatible with reversible processes involving oxidised species. Isotope anomalies in pyrite from the Dresser Formation, Australia, are compatible with post-depositional incorporation of 2-5% sulphur of atmospheric origin. Overall, observed delta values could mainly be related to changes in the local absolute isotope abundances.


Assuntos
Sedimentos Geológicos/química , Ferro/química , Modelos Teóricos , Sulfetos/química , Enxofre/química , Archaea/química , Fracionamento Químico , Isótopos de Oxigênio/análise , Isótopos de Enxofre/análise
13.
Chem Commun (Camb) ; 55(86): 13004-13007, 2019 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-31608907

RESUMO

An ultrasonication-promoted strategy was proposed to synthesize luminescent S-dots, which reduced the synthesis time from the commonly used 5 days to several hours. The as-synthesized S-dots show a high photostability and low cytotoxicity, and are then successfully applied for cellular imaging.


Assuntos
Pontos Quânticos/química , Enxofre/química , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Humanos , Microscopia Confocal , Polietilenoglicóis/química , Pontos Quânticos/toxicidade , Sonicação
14.
Molecules ; 24(19)2019 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-31590359

RESUMO

Hybrids containing approximately equal amounts of P25 TiO2 and S-doped porous carbons were prepared using a water-based slurry mixing method. The materials were extensively characterized by adsorption of nitrogen, potentiometric titration, thermal analysis in air and in helium, XRD, XPS and SEM. The collected results showed the significant blockage of carbon micropores by TiO2 particles deposited on their outer surface. The formation of a new interface, especially for the S-rich samples, might also contribute to the porosity alteration. Analysis of surface chemistry suggested the presence of Ti-S bonds with an involvement of sulfur from thiophenic species in the carbon phase. The latter, especially when polymer-derived, was mainly deposited on the TiO2 nanoparticles. Formation of Ti-S stabilized sulfur and increased the ignition temperature of the hybrids, especially those with a high content of sulfur, in comparison with the ignition temperature of carbons. The surfaces of hybrid with S-containing carbons was also thermally very stable and of basic chemical nature. The formation of interfacial structures Ti-C was detected by XPS analysis suggesting a partial reduction of the Ti.


Assuntos
Carbono/química , Enxofre/química , Titânio/química , Adsorção , Catálise , Nanopartículas/química , Porosidade , Propriedades de Superfície , Temperatura
15.
Mater Sci Eng C Mater Biol Appl ; 105: 110132, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31546396

RESUMO

In this work, nitrogen and sulfur dual-doped carbon quantum dots (N,S-CDs) from naturally renewable biomaterial fungus fibers were prepared by a biosynthesis and hydrothermal method. The N,S-CDs displayed good water solubility, excellent stability, high quantum yield (QY = 28.11%) as well as remarkable features for fluorescence quenching-based detection and cellular imaging of cancer cells. It was worth mentioning that the heteroatoms doped carbon quantum dots made from the fungus fibers had a satisfactory QY and could be used as a selective, efficient, and sensitive fluorescent probe to determine tetracyclines by the synergistic effects of static quenching and internal filtration effect. The probe demonstrated a wide linear range and low detection limit. For tetracycline, the linear range was 0.5 µM to 47.6 µM, and the corresponding detection limit was 15.6 nM. Significantly, the test papers prepared by using N,S-CDs could detect tetracyclines in aquiculture wastewater rapidly. The produced N,S-CDs did not affect the cell viability and showed great promises for cellular imaging.


Assuntos
Carbono/química , Fungos/química , Imageamento Tridimensional , Neoplasias/diagnóstico por imagem , Nitrogênio/química , Pontos Quânticos/química , Enxofre/química , Tetraciclinas/análise , Morte Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Hep G2 , Humanos , Neoplasias/patologia , Tamanho da Partícula , Pontos Quânticos/ultraestrutura , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Tetraciclinas/farmacologia , Águas Residuárias/química
16.
Molecules ; 24(18)2019 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-31546827

RESUMO

Potassium metabisulphite is usually used for microbial stabilization in the process of vinification and wine preservation, but it is considered to be allergenic. The objective of the present study was to assess the efficiency of ozonation and ionizing radiation as alternatives to wine sulphurization. The efficiency of yeast removal and the retention of the chemical quality of wine were evaluated. Wine was subjected to 60 min of ozonation, and radiation doses were set at 1-10 kGy. Moreover, a combination of ozonation and ionizing radiation treatment was used. The ozonation of wine did not produce the expected results. That is, it did not limit the number of yeast cells. From the sixth minute, a significant deterioration in the taste and the color of the wine was found. Ionizing radiation at a dose of 1 kGy reduced the yeast count by 95.5%, and a reduction of 99.9% was seen after the application of 2.5 kGy. Moreover, these doses did not have a significant effect on the organoleptic properties or the chemical composition of wine. The total amount of polyphenols reduced from the maximum of 1127.15 to 1023.73 mg at the dose of 5 kGy. Radiation is widely used to preserve food products. Its use for finished wine preservation may be an alternative to sulphurization.


Assuntos
Elétrons , Conservação de Alimentos , Ozônio/química , Enxofre/química , Vinho/análise , Viabilidade Microbiana/efeitos dos fármacos , Sensação , Sulfitos/farmacologia , Fatores de Tempo , Vinho/microbiologia , Leveduras/efeitos dos fármacos
17.
Carbohydr Polym ; 224: 115191, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31472875

RESUMO

κ-Carrageenan-based (Carr) functional wound healing hydrogel films were prepared by incorporating chitosan capped sulfur nanoparticles (SNP) and grapefruit seed extract (GSE). In vivo wound healing effect of the hydrogel films was tested using artificially wounded male Sprague-Dawley rats. The hydrogel film (Carr/GSE/SNP) showed higher mechanical strength, swelling ratio and ultraviolet barrier properties than the carrageenan film, but the water vapor permeability and water solubility were decreased. The hydrogel film showed antibacterial activity strong enough to destroy Staphylococcus epidermis and Escherichia coli within 3 h of incubation and showed high biocompatibility against mouse fibroblast (L929 cell lines). The hydrogel film (Carr/GSE/SNP3%) showed excellent wound healing effect (1.3% wound area after 2 weeks) compared to the control group (31% wound area after 2 weeks) through in vivo wound healing test. Histological examination showed the complete appearance of the healed epidermis. The Carr/GSE/SNP hydrogel films are most likely to be used for the treatment of full-thickness wounds.


Assuntos
Carragenina/química , Citrus paradisi/química , Hidrogéis/química , Hidrogéis/farmacologia , Extratos Vegetais/química , Enxofre/química , Cicatrização/efeitos dos fármacos , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Linhagem Celular , Escherichia coli/efeitos dos fármacos , Fenômenos Mecânicos , Camundongos , Nanopartículas/química , Permeabilidade , Ratos , Ratos Sprague-Dawley , Sementes/química , Solubilidade , Staphylococcus epidermidis/efeitos dos fármacos , Vapor
18.
Chem Asian J ; 14(21): 3898-3914, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31545553

RESUMO

Simultaneous incorporation of both CoII and CoIII ions within a new thioether S-bearing phenol-based ligand system, H3 L (2,6-bis-[{2-(2-hydroxyethylthio)ethylimino}methyl]-4-methylphenol) formed [Co5 ] aggregates [CoII CoIII 4 L2 (µ-OH)2 (µ1,3 -O2 CCH3 )2 ](ClO4 )4 ⋅H2 O (1) and [CoII CoIII 4 L2 (µ-OH)2 (µ1,3 -O2 CC2 H5 )2 ](ClO4 )4 ⋅H2 O (2). The magnetic studies revealed axial zero-field splitting (ZFS) parameter, D/hc=-23.6 and -24.3 cm-1 , and E/D=0.03 and 0.00, respectively for 1 and 2. Dynamic magnetic data confirmed the complexes as SIMs with Ueff /kB =30 K (1) and 33 K (2), and τ0 =9.1×10-8  s (1), and 4.3×10-8  s (2). The larger atomic radius of S compared to N gave rise to less variation in the distortion of tetrahedral geometry around central CoII centers, thus affecting the D and Ueff /kB values. Theoretical studies also support the experimental findings and reveal the origin of the anisotropy parameters. In solutions, both 1 and 2 which produce {CoIII 2 (µ-L)} units, display solvent-dependent catechol oxidation behavior toward 3,5-di-tert-butylcatechol in air. The presence of an adjacent CoIII ion tends to assist the electron transfer from the substrate to the metal ion center, enhancing the catalytic oxidation rate.


Assuntos
Catecol Oxidase/química , Cobalto/química , Complexos de Coordenação/síntese química , Sulfetos/química , Enxofre/química , Catecol Oxidase/metabolismo , Cobalto/metabolismo , Complexos de Coordenação/química , Complexos de Coordenação/metabolismo , Cristalografia por Raios X , Peróxido de Hidrogênio/análise , Cinética , Ligantes , Campos Magnéticos , Modelos Moleculares , Estrutura Molecular , Oxirredução , Sulfetos/metabolismo , Enxofre/metabolismo
19.
Anal Bioanal Chem ; 411(27): 7137-7146, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31511944

RESUMO

The application of carbon dots as a coreactant for Ru(bpy)32+ (where bpy is 2,2'-bipyridine) electrochemiluminescence (ECL) has been widely studied. However, the high cost of Ru(bpy)32+ and its derivatives has prohibited its widespread use in ECL biosensors. Herein, a novel anodic ECL system based on sulfur-doped graphitic carbon nitride nanosheets (S-g-C3N4 NSs) and nitrogen-doped carbon dots (N-CDs) is presented. In this ECL system, N-CDs serve as a new ECL coreactant that can significantly enhance the anodic ECL signal of S-g-C3N4 NSs (approximately 83 times) under optimal conditions. The possible ECL response mechanism of the S-g-C3N4 NSs/N-CDs system is proposed in detail on the basis of cyclic voltammograms, ECL-time curves, and ECL spectra. Furthermore, the ECL signal of the S-g-C3N4 NSs/N-CDs system was quenched by folic acid (FA), which was chosen as a model analyte to study the potential application of the new ECL system. The ECL intensity decreased linearly with the concentration of FA in the range from 0.05 to 200 µM. The detection limit for FA measurement is 16 nM (signal-to-noise ratio of 3). The proposed new ECL system has many advantages over traditional approaches, such as low toxicity and excellent biocompatibility. Especially, the proposed approach can detect FA in diluted human serum samples with satisfactory recoveries, indicating promising application for bioanalysis. Graphical abstract.


Assuntos
Carbono/química , Técnicas Eletroquímicas/métodos , Eletrodos , Ácido Fólico/sangue , Nanoestruturas/química , Nitrilos/química , Nitrogênio/química , Enxofre/química , Técnicas Biossensoriais , Técnicas Eletroquímicas/instrumentação , Humanos , Limite de Detecção , Luminescência , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
20.
Chemistry ; 25(67): 15351-15360, 2019 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-31486181

RESUMO

In Rhodospirillum rubrum, the maturation of carbon monoxide dehydrogenase (CODH) requires three nickel chaperones, namely RrCooC, RrCooT and RrCooJ. Recently, the biophysical characterisation of the RrCooT homodimer and the X-ray structure of its apo form revealed the existence of a solvent-exposed NiII -binding site at the dimer interface, involving the strictly conserved Cys2. Here, a multifaceted approach that used NMR and X-ray absorption spectroscopies, complemented with structural bio-modelling methodologies, was used to characterise the binding mode of NiII in RrCooT. This study suggests that NiII adopts a square-planar geometry through a N2 S2 coordinating environment that comprises the two thiolate and amidate groups of both Cys2 residues at the dimer interface. The existence of a diamagnetic mononuclear NiII centre with bis-amidate/bis-thiolate ligands, coordinated by a single-cysteine motif, is unprecedented in biology and raises the question of its role in the activation of CODH at the molecular level.


Assuntos
Cisteína/química , Metalochaperonas/química , Níquel/química , Rhodospirillum rubrum/química , Sequência de Aminoácidos , Sítios de Ligação , Cátions Bivalentes/química , Complexos de Coordenação/química , Ligantes , Modelos Moleculares , Nitrogênio/química , Ligação Proteica , Conformação Proteica , Multimerização Proteica , Solventes/química , Enxofre/química , Termodinâmica
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA