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1.
Nat Protoc ; 15(9): 2980-3008, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32839575

RESUMO

High-surface-area mesoporous materials expose abundant functional sites for improved performance in applications such as gas storage/separation, catalysis, and sensing. Recently, soft templates composed of amphiphilic surfactants and block copolymers have been used to introduce mesoporosity in various materials, including metals, metal oxides and carbonaceous compounds. In particular, mesoporous metals are attractive in electrocatalysis because their porous networks expose numerous unsaturated atoms on high-index facets that are highly active in catalysis. In this protocol, we describe how to create mesoporous metal films composed of gold, palladium, or platinum using block copolymer micelle templates. The amphiphilic block copolymer micelles are the sacrificial templates and generate uniform structures with tunable pore sizes in electrodeposited metal films. The procedure describes the electrodeposition in detail, including parameters such as micelle diameters, deposition potentials, and deposition times to ensure reproducibility. The micelle diameters can be controlled by swelling the micelles with different solvent mixtures or by using block copolymer micelles with different molecular weights. The deposition potentials and deposition times allow further control of the mesoporous structure and its thickness, respectively. Procedures for example applications are included: glucose oxidation, ethanol oxidation and methanol oxidation reactions. The synthetic methods for preparation of mesoporous metal films will take ~4 h; the subsequent electrochemical tests will take ~5 h for glucose sensing and ~3 h for alcohol oxidation reaction.


Assuntos
Ouro/química , Paládio/química , Platina/química , Álcoois/química , Catálise , Técnicas de Química Sintética , Eletroquímica , Interações Hidrofóbicas e Hidrofílicas , Micelas , Modelos Moleculares , Conformação Molecular , Oxirredução , Polímeros/química
2.
Int J Mol Sci ; 21(15)2020 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-32717853

RESUMO

As SARS-CoV-2 is spreading rapidly around the globe, adopting proper actions for confronting and protecting against this virus is an essential and unmet task. Reactive oxygen species (ROS) promoting molecules such as peroxides are detrimental to many viruses, including coronaviruses. In this paper, metal decorated single-wall carbon nanotubes (SWCNTs) were evaluated for hydrogen peroxide (H2O2) adsorption for potential use for designing viral inactivation surfaces. We employed first-principles methods based on the density functional theory (DFT) to investigate the capture of an individual H2O2 molecule on pristine and metal (Pt, Pd, Ni, Cu, Rh, or Ru) decorated SWCNTs. Although the single H2O2 molecule is weakly physisorbed on pristine SWCNT, a significant improvement on its adsorption energy was found by utilizing metal functionalized SWCNT as the adsorbent. It was revealed that Rh-SWCNT and Ru-SWCNT systems demonstrate outstanding performance for H2O2 adsorption. Furthermore, we discovered through calculations that Pt- and Cu-decorated SWNCT-H2O2 systems show high potential for filters for virus removal and inactivation with a very long shelf-life (2.2 × 1012 and 1.9 × 108 years, respectively). The strong adsorption of metal decorated SWCNTs and the long shelf-life of these nanomaterials suggest they are exceptional candidates for designing personal protection equipment against viruses.


Assuntos
Betacoronavirus/efeitos dos fármacos , Desinfetantes/farmacologia , Peróxido de Hidrogênio/análise , Nanotubos de Carbono/química , Adsorção , Infecções por Coronavirus/prevenção & controle , Teoria da Densidade Funcional , Desinfetantes/química , Estabilidade de Medicamentos , Humanos , Ferro/química , Ferro/farmacologia , Pandemias/prevenção & controle , Equipamento de Proteção Individual , Platina/química , Platina/farmacologia , Pneumonia Viral/prevenção & controle , Ródio/química , Ródio/farmacologia , Rutênio/química , Rutênio/farmacologia , Inativação de Vírus
3.
Nat Commun ; 11(1): 3178, 2020 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-32576814

RESUMO

Sophisticated mechanically interlocked molecules (MIMs) with interesting structures, properties and applications have attracted great interest in the field of supramolecular chemistry. We herein report a highly efficient self-assembly of heterometallic triangular necklace 1 containing Cu and Pt metals with strong antibacterial activity. Single-crystal X-ray analysis shows that the finely arranged triangular necklace 1 has two racemic enantiomers in its solid state with intriguing packing motif. The superior antibacterial activity of necklace 1 against both standard and clinically drug-resistant pathogens implies that the presence of Cu(I) center and platinum(II) significantly enhance the bacterium-binding/damaging activity, which is mainly attributed to the highly positively charged nature, the possible synergistic effect of heterometals in the necklace, and the improved stability in culture media. This work clearly discloses the structure-property relationships that the existence of two different metal centers not only facilitates successful construction of heterometallic triangular necklace but also endows it with superior nuclease properties and antibacterial activities.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Compostos Organometálicos/química , Compostos Organometálicos/farmacologia , Bactérias/efeitos dos fármacos , Cobre/química , Cristalografia por Raios X , Clivagem do DNA/efeitos dos fármacos , Farmacorresistência Bacteriana/efeitos dos fármacos , Espectroscopia de Ressonância Magnética , Testes de Sensibilidade Microbiana , Modelos Moleculares , Estrutura Molecular , Platina/química , Estereoisomerismo
4.
J Vis Exp ; (159)2020 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-32478752

RESUMO

The synthesis of high surface area porous noble metal nanomaterials generally relies on time consuming coalescence of pre-formed nanoparticles, followed by rinsing and supercritical drying steps, often resulting in mechanically fragile materials. Here, a method to synthesize nanostructured porous platinum-based macrotubes and macrobeams with a square cross section from insoluble salt needle templates is presented. The combination of oppositely charged platinum, palladium, and copper square planar ions results in the rapid formation of insoluble salt needles. Depending on the stoichiometric ratio of metal ions present in the salt-template and the choice of chemical reducing agent, either macrotubes or macrobeams form with a porous nanostructure comprised of either fused nanoparticles or nanofibrils. Elemental composition of the macrotubes and macrobeams, determined with x-ray diffractometry and x-ray photoelectron spectroscopy, is controlled by the stoichiometric ratio of metal ions present in the salt-template. Macrotubes and macrobeams may be pressed into free standing films, and the electrochemically active surface area is determined with electrochemical impedance spectroscopy and cyclic voltammetry. This synthesis method demonstrates a simple, relatively fast approach to achieve high-surface area platinum-based macrotubes and macrobeams with tunable nanostructure and elemental composition that may be pressed into free-standing films with no required binding materials.


Assuntos
Nanoestruturas/química , Platina/química
5.
Nat Commun ; 11(1): 2051, 2020 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-32345967

RESUMO

A key challenge for designing hybrid materials is the development of chemical tools to control the organization of inorganic nanoobjects at low scales, from mesoscopic (~µm) to nanometric (~nm). So far, the most efficient strategy to align assemblies of nanoparticles consists in a bottom-up approach by decorating block copolymer lamellae with nanoobjects. This well accomplished procedure is nonetheless limited by the thermodynamic constraints that govern copolymer assembly, the entropy of mixing as described by the Flory-Huggins solution theory supplemented by the critical influence of the volume fraction of the block components. Here we show that a completely different approach can lead to tunable 2D lamellar organization of nanoparticles with homopolymers only, on condition that few elementary rules are respected: 1) the polymer spontaneously allows a structural preorganization, 2) the polymer owns functional groups that interact with the nanoparticle surface, 3) the nanoparticles show a surface accessible for coordination.


Assuntos
Nanopartículas Metálicas/química , Peptídeos/química , Platina/química , Polímeros/química , Nanopartículas Metálicas/ultraestrutura , Espectroscopia Fotoeletrônica , Polimerização
6.
Environ Toxicol ; 35(9): 930-941, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32309901

RESUMO

Platinum nanoparticles (PtNPs) attract much attention due to their excellent biocompatibility and catalytic properties, but their toxic effects on normal (CHANG) and cancerous (HuH-7) human liver cells are meagre. The cytotoxic and apoptotic effects of PtNPs (average size, 3 nm) were determined in CHANG and HuH-7 cells. After treating these cells were with PtNPs (10, 50, 100, 200, and 300 µg/mL) for 24 and 48 hours, we observed dose- and time-dependent cytotoxicity, as evaluated by using (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide, a tetrazole) (MTT) and neutral red uptake (NRU) assays. The production of reactive oxygen species (ROS) was increased in both cells after treatment with the above dose of PtNPs for 24 and 48 hours. Determination of morphological changes of cells, chromosome condensation, mitochondrial membrane potential, and caspase-3 assays showed that PtNPs induce cytotoxicity and apoptosis in CHANG and HuH-7 cells by altering the cell morphology and density, increasing cell population in apoptosis, and causing chromosome condensation. Furthermore, we have studied fragmentation of DNA using alkaline single cell gel electrophoresis and expression of apoptotic genes by real-time PCR (RT-PCR). The percentage of DNA fragmentation was more at 300 µg/mL for 48 hours in both cells, but slightly more fragmentation was found in HuH-7 relative to CHANG cells. Considering all of the above parameters, PtNPs elicited cytotoxicity on CHANG and HuH-7 cells by blocking cell proliferation and inducing apoptosis. Thus this study may be useful in in vitro laboratory studies using cell lines for screening the genotoxic and apoptotic potential of nanoparticles.


Assuntos
Apoptose/efeitos dos fármacos , Dano ao DNA , Expressão Gênica/efeitos dos fármacos , Fígado/efeitos dos fármacos , Nanopartículas Metálicas/química , Estresse Oxidativo/efeitos dos fármacos , Platina/farmacologia , Apoptose/genética , Caspase 3/genética , Caspase 3/metabolismo , Morte Celular , Linhagem Celular Tumoral , Fragmentação do DNA/efeitos dos fármacos , Humanos , Fígado/metabolismo , Fígado/patologia , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Estresse Oxidativo/genética , Platina/química , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Proteína X Associada a bcl-2/genética , Proteína X Associada a bcl-2/metabolismo
7.
Int J Nanomedicine ; 15: 169-179, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32021172

RESUMO

Background: Cancer is a disease with an enormous worldwide impact. One of the fatal complications in cancer patients are bacterial opportunistic infections. The use of chemotherapeutic drugs made cancer remission more frequent and prolonged patient survival, but, increased the risk of infections. Purpose: Address the current problem with growing pandemic cancer and considering high risks of complications with bacterial infections, the present study synthesized novel dendritic assembly of silver (Ag)-platinum (Pt) nanoparticles. Methods: Nanoparticles were characterized by TEM analysis, and the composition was confirmed by EDX. Bacterial studies were performed for Gram-positive Staphylococcus aureus, Gram-negative Pseudomonas aeruginosa and Gram-negative multi-drug resistant Escherichia coli. Cell experiments were performed with two different cancer cell lines, glioblastoma and melanoma to determine anticancer activity. Finally, cytotoxicity with fibroblast was tested. Results: The TEM analysis of silver-platinum (AgPt) nanoparticles showed dendrimer shape nanoparticles with a mean size of 42 ± 11nm. Elemental composition was analyzed by EDX, confirming the presence of both Ag and Pt metals. The synthesized nanoparticles significantly inhibited the growth of medically important pathogenic, Gram-positive Staphylococcus aureus, Gram-negative Pseudomonas aeruginosa and Gram-negative multi-drug resistant Escherichia coli. Bactericidal effect of AgPt nanoparticles had greater effectiveness than silver nanoparticles. MTS assay revealed a selective and dose-dependent anticancer activity of AgPt nanoparticles over cancer cell lines glioblastoma and melanoma in the 10-250 µg/mL concentration range. Cytotoxicity experiments with fibroblast cells showed no side effects of nanoparticles against healthy cells at a range of concentrations from 10-50 µg/mL. Conclusion: The newly synthesized AgPt nanoparticles have a promising future as a potent anticancer agent with antibacterial properties.


Assuntos
Antibióticos Antineoplásicos/farmacologia , Nanopartículas Metálicas/uso terapêutico , Platina/farmacologia , Prata/farmacologia , Antibióticos Antineoplásicos/química , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Glioblastoma/tratamento farmacológico , Glioblastoma/patologia , Humanos , Melanoma/tratamento farmacológico , Melanoma/patologia , Nanopartículas Metálicas/química , Testes de Sensibilidade Microbiana , Platina/química , Pseudomonas aeruginosa/efeitos dos fármacos , Prata/química , Staphylococcus aureus/efeitos dos fármacos
8.
J Phys Chem Lett ; 11(5): 1697-1701, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-32039604

RESUMO

Here we demonstrate sub-10 nm spatial resolution sampling of a volume of ∼360 molecules with a strong field enhancement at the sample-tip junction by implementing noble metal substrates (Au, Ag, Pt) in photoinduced force microscopy (PiFM). This technique shows the versatility and robustness of PiFM and is promising for application in interfacial studies with hypersensitivity and super spatial resolution.


Assuntos
Metais/química , Microscopia de Força Atômica/métodos , Animais , Bovinos , Ouro/química , Platina/química , Soroalbumina Bovina/química , Dióxido de Silício/química , Prata/química
9.
Chemosphere ; 248: 126043, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32007768

RESUMO

A Pt catalyst supported on activated carbon (Pt/AC) was used for an environmentally friendly thermal treatment of food waste under an inert atmosphere (i.e., pyrolysis). This catalyst influenced the amounts of condensable hydrocarbons and noncondensable gases but not that of the solid remaining after the pyrolysis; in particular, it contributed to shifting the carbon distribution from the condensable hydrocarbons to the noncondensable gases for the food waste pyrolysis. Moreover, its use suppressed the generation of harmful chemical compounds, especially at high temperatures. For example, a Pt/AC-catalyzed pyrolysis at 700 °C produced about 4 times fewer benzene derivatives than the same treatment without a catalyst; this probably occurred because the Pt sites catalyzed the decyclization reaction and/or the free radical mechanism, which is dominant in the thermal cracking of carbon-containing feedstock. This study suggests that a Pt/AC-catalyzed pyrolysis would be a more environmentally benign food waste treatment method.


Assuntos
Alimentos , Hidrocarbonetos/química , Pirólise , Eliminação de Resíduos/métodos , Catálise , Gases , Temperatura Alta , Platina/química
10.
Chem Commun (Camb) ; 56(20): 3069-3072, 2020 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-32049075

RESUMO

Niacin-ligated platinum(iv)-ruthenium(ii) chimeric complexes (PtRu 1-4) have been synthesized and evaluated for their antitumor performance. Using the optimal complex, PtRu-1, we show that this water-soluble chimeric prodrug not only potently inhibits the metastasis and proliferation of tumor cells but also has an unexpectedly higher safety margin in animals compared with the traditionally-used, clinically approved drug cisplatin.


Assuntos
Antineoplásicos/farmacologia , Complexos de Coordenação/farmacologia , Niacina/farmacologia , Platina/farmacologia , Rutênio/farmacologia , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Peso Corporal/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cisplatino/química , Cisplatino/farmacologia , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos ICR , Camundongos Nus , Estrutura Molecular , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/patologia , Niacina/química , Platina/química , Rutênio/química , Relação Estrutura-Atividade
11.
Food Chem ; 315: 126306, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32035315

RESUMO

In this work we propose the use of statistical mixture design in the construction of a biosensor device based on graphite oxide, platinum nanoparticles and biomaterials obtained from Botryosphaeria rhodina MAMB-05. The biosensor was characterized by electrochemical impedance spectroscopy. Under optimized experimental parameters by factorial design, the biosensor was applied to the voltammetric determination of chlorogenic acid (CGA) measured as 5-O-caffeoylquinic acid (5-CQA). The biosensor response was linear (R2 = 0.998) for 5-CQA in the concentration range 0.56-7.3 µmol L-1, with limit of detection and quantification of 0.18 and 0.59 µmol L-1, respectively. The new biosensing device was applied to quality control analysis based upon the determination of CGA content in specialty and traditional coffee beverages. The results indicated that specialty coffee had a significantly higher content of CGA. Principal component analysis of the voltammetric fingerprint of brewed coffees revealed that the laccase-based biosensor can be used for their discrimination.


Assuntos
Bebidas/análise , Ácido Clorogênico/análogos & derivados , Café/química , Ácido Quínico/análogos & derivados , Técnicas Biossensoriais/métodos , Ácido Clorogênico/análise , Nanopartículas Metálicas/química , Platina/química , Ácido Quínico/análise
12.
Ann Biol Clin (Paris) ; 78(1): 54-60, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32108579

RESUMO

The realization of the antibiotic susceptibility test in agar is the routine bacteriological examination for the determination and monitoring of bacterial susceptibility to antibiotics. In this study, we report the comparative results between pencil leads for criterium, as an alternative to platinum rods in the realization of the antibiotic susceptibility test. METHODOLOGY: Experimental study evaluating the comparability of the results between Criterium and Inoclic mines (by counting bacterial cells on agar after 5 successive dilutions of reason 10 from a bacterial suspension obtained after piercing through a colony; by measuring the inhibition diameters of 4 ATCC reference bacterial strains on an antibiogram in an agar medium) and evaluating the sterility of the criterium mines by culturing them on enriched broth (heart - brain type). RESULTS: 42 bacterial strains were used for bacterial cell counting. The results were of the same order of magnitude (107 CFU/mL) between Inoclic and criterium mines, for all strains and at all dilutions. The antibiotic susceptibility tests performed for the 4 reference strains by the Inoclics and criterium mines all complied (100%) with the expected limits for determining their sensitivity profile to the antibiotics tested. Compared to the bacterial growth inhibition diameters on antibiotic susceptibility tests, no intra-operator variability was observed, while significant inter-operator variability (both with Inoclic and 0.5 mm criterium mines) was observed with some strains and for inhibition diameters greater than 10 mm. The enriched broth cultures (BCC) and their subculture carried out on 10 criterium mines from 5 different batches were negative. CONCLUSION: Criterium mines seem to be a serious and less expensive alternative to Inoclic for the realization of antibiotic susceptibility testing in our resource-limited countries.


Assuntos
Ágar/química , Técnicas Bacteriológicas/economia , Técnicas Bacteriológicas/métodos , Meios de Cultura/química , Antibacterianos/farmacologia , Meios de Cultura/economia , Escherichia coli/efeitos dos fármacos , Escherichia coli/fisiologia , Grafite/química , Grafite/economia , Humanos , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/fisiologia , Testes de Sensibilidade Microbiana/economia , Testes de Sensibilidade Microbiana/métodos , Platina/química , Platina/economia , Áreas de Pobreza , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/fisiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/fisiologia
13.
Talanta ; 211: 120707, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32070586

RESUMO

In this study, a colorimetric sensing assay of isoniazid based on excellent oxidase-like activity of heparin sodium stabilized platinum nanoparticles (HS-PtNPs) has been demonstrated. The newly prepared HS-PtNPs exhibit a great dispersion with an average size distribution of 4.8 ± 0.6 nm, and maintain more than 90% catalytic activity under strong acid and alkali or long-term storage conditions, indicating a robust nanomaterial with attractive potential. The HS-PtNPs show distinct oxidase-like activity with an ultrahigh affinity (Km = 0.01012 mM) for 3, 3', 5, 5'-tetramethylbenzidine (TMB). More significantly, we found that the pyridine ring of isoniazid has a strong reductive hydrazyl substitution, which can compete with TMB for the catalytic site of HS-PtNPs resulting in a colorless solution. Accordingly, a colorimetric sensing of isoniazid was fabricated. A linear relationship for isoniazid was achieved in 2.5 × 10-6 to 2.5 × 10-4 M (R2 = 0.998) with a low limit of detection 1.7 × 10-6 M (S/N = 3). Recovery experiments in drug tablets show that the standard recovery rates were 95%-103%. The quantitative detection data for isoniazid in drug tablets calculated respectively from the standard method and this method exhibited a high correlation coefficient (a slope of 0.9995), suggesting that high accuracy in isoniazid detection.


Assuntos
Antituberculosos/análise , Heparina/química , Isoniazida/análise , Nanopartículas Metálicas/química , Platina/química , Antituberculosos/química , Benzidinas/química , Colorimetria , Isoniazida/química , Oxirredutases/química , Comprimidos
14.
Chemistry ; 26(9): 1947-1952, 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-31909511

RESUMO

Platinum-based chemotherapy persists to be the only effective therapeutic option against a wide variety of tumours. Nevertheless, the acquisition of platinum resistance is utterly common, ultimately cornering conventional platinum drugs to only palliative in many patients. Thus, encountering alternatives that are both effective and non-cross-resistant is urgent. In this work, we report the synthesis, reduction studies, and luminescent properties of a series of cyclometallated (C,N,N')PtIV compounds derived from amine-imine ligands, and their remarkable efficacy at the high nanomolar range and complete lack of cross-resistance, as an intrinsic property of the platinacycle, against multiplatinum-resistant colorectal cancer (CRC) and castration-resistant prostate cancer (CRPC) metastatic cell lines generated for this work. We have also determined that the compounds are effective and selective for a broader cancer panel, including breast and lung cancer. Additionally, selected compounds have been further evaluated, finding a shift in their antiproliferative mechanism towards more cytotoxic and less cytostatic than cisplatin against cancer cells, being also able to oxidize cysteine residues and inhibit topoisomerase II, thereby holding great promise as future improved alternatives to conventional platinum drugs.


Assuntos
Antineoplásicos/farmacologia , Proliferação de Células/efeitos dos fármacos , Complexos de Coordenação/química , Resistencia a Medicamentos Antineoplásicos , Platina/química , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Cisplatino/farmacologia , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Complexos de Coordenação/farmacologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Masculino , Conformação Molecular , Neoplasias de Próstata Resistentes à Castração/metabolismo , Neoplasias de Próstata Resistentes à Castração/patologia , Espectrometria de Fluorescência
15.
Cell Biochem Biophys ; 78(1): 15-22, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31893350

RESUMO

Anions enter from the cytoplasm into the channel pore of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel not via a central pathway but via a single lateral portal or fenestration. High Cl- conductance is dependent on electrostatic attraction of cytoplasmic Cl- ions by four positively charged amino acid side-chains located within this portal. Here we use a mutagenic approach to investigate the functional effects of transplanting or supplementing these positive charges at nearby portal-lining sites. Using patch clamp recording, we find that the functionally important positive charges at K190 and R303 can be transplanted to four nearby sites (N186, L197, W356, and A367) with little loss of Cl- conductance. Introduction of additional positive charge at these sites had almost no effect on Cl- conductance, but did increase the sensitivity to channel block by intracellular suramin and Pt(NO2)42- anions. We suggest that it is the number of positive charges within the portal, rather than their exact location, that is the most important factor influencing Cl- conductance. The portal appears well optimized in terms of charge distribution to maximize Cl- conductance.


Assuntos
Regulador de Condutância Transmembrana em Fibrose Cística/metabolismo , Citoplasma/metabolismo , Animais , Ânions/química , Ânions/metabolismo , Linhagem Celular , Complexos de Coordenação/química , Complexos de Coordenação/metabolismo , Cricetinae , Regulador de Condutância Transmembrana em Fibrose Cística/antagonistas & inibidores , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Humanos , Mutagênese Sítio-Dirigida , Técnicas de Patch-Clamp , Platina/química , Eletricidade Estática , Suramina/química , Suramina/metabolismo
16.
Chem Commun (Camb) ; 56(12): 1784-1787, 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-31950129

RESUMO

Nanozymes have attracted extensive attention due to their great potential as alternatives to natural enzymes. Optical control as an external stimulus has become the most attractive method because of its high spatial and temporal resolution. Under the action of excitation light, free electrons on the surface of gold nanorods (GNRs) will collectively oscillate, which is called localized surface plasmon resonance (LSPR). This unique LSPR effect is promising in the application of plasmon-accelerated enzyme-like catalytic reactions. Pt-tipped gold nanorod-based nanozymes (Pt-GNRs) were synthesized by the modification of Pt nanoclusters onto the tips of GNRs. The as-prepared Pt-GNRs exhibited excellent enzyme-like catalytic activity toward hydrogen peroxide. Furthermore, it was found that the enzyme-like catalytic activity of Pt-GNRs could be notably enhanced using near-infrared (NIR) light irradiation, because of the photothermal effect and hot electron effect produced by the LSPR of GNRs. Finally, the catalytic activity and cytotoxicity of Pt-GNRs were evaluated in 4T1 cells, which further demonstrated that the Pt-GNR-based nanozymes possess great potential in cancer treatment.


Assuntos
Antineoplásicos/química , Ouro/química , Nanopartículas Metálicas/química , Platina/química , Ressonância de Plasmônio de Superfície , Antineoplásicos/farmacologia , Catálise , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Ouro/farmacologia , Humanos , Raios Infravermelhos , Platina/farmacologia , Relação Estrutura-Atividade
17.
Nat Commun ; 11(1): 408, 2020 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-31964865

RESUMO

Biological systems are known to spontaneously adjust the functioning of neurotransmitters, ion channels, and the immune system, being promoted or regulated through allosteric effects or inhibitors, affording non-linear responses to external stimuli. Here we report that an insulated conjugated bimetallopolymer, in which Ru(II) and Pt(II) complexes are mutually connected with insulated conjugations, exhibits phosphorescence in response to CO gas. The net profile corresponds to a sigmoidal response with a dual self-controlling system, where drastic changes were exhibited at two threshold concentrations. The first threshold for activation of the system is triggered by the depolymerization of the non-radiative conjugated polymer to luminescent monomers, while the second one for regulation is triggered by the switch in the rate-determining step of the Ru complex. Such a molecular design with cooperative multiple transition metals would provide routes for the development of higher-ordered artificial molecular systems bearing bioinspired responses with autonomous modulation.


Assuntos
Materiais Biomiméticos/química , Complexos de Coordenação/química , Polímeros/química , Materiais Inteligentes/química , Monóxido de Carbono/análise , Luminescência , Platina/química , Rutênio/química , alfa-Ciclodextrinas/química
18.
Chemosphere ; 243: 125387, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31995867

RESUMO

Hollow porous carbon has attracted a great deal of interest as catalyst-support because of its high surface area, low density and large pore volume. Herein, we develop a layer-by-layer assembly method to effectively load Pt nanoparticles on hollow porous carbon nanospheres (Pt/HPC) through using modified-SiO2 nanospheres as the template and agar as the carbon resource. The gel properties of agar (e.g., sensitivity to temperature and high mechanical strength) makes the Pt nanoparticles well crosslink with carbon, as well as endows the carbon nanospheres with robust stability. The synthesized Pt/HPC was employed as a catalyst in the hydrogenation reduction of rhodamine B (RhB). The catalytic results demonstrate that Pt/HPC is very promising for RhB hydrogenation as compared to commercial Pt/C catalyst. It is proven that such excellent activity of Pt/HPC can be attributed to the combined merits of hollow porous architecture and well combination between HPC and Pt nanoparticles.


Assuntos
Ágar/química , Nanosferas/química , Platina/química , Rodaminas/química , Carbono/química , Catálise , Reagentes para Ligações Cruzadas/química , Hidrogenação , Nanopartículas Metálicas/química , Porosidade , Dióxido de Silício , Temperatura
19.
Anal Chim Acta ; 1097: 186-195, 2020 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-31910959

RESUMO

A simple electrochemical strategy has been designed for the analysis of MUC1 using electrodeposited gold platinum bimetallic nanoparticles (Au-PtBNPs) on the surface of carboxylated graphene oxide (CGO)/FTO electrode as a signal amplification platform. The carboxylic groups of CGO were activated with EDS-NHS linker and subsequently immobilized with streptavidin for further deposition of biotin labelled aptamer. All the modification steps were characterized by FE-SEM, EDS mapping, FT-IR, contact angle measurements and electrochemical methods. After incubating with target protein MUC1, the aptaelectrode produced some concentration dependent responses which were measured electrochemically by DPV assay. The prepared aptasensor exhibits wide linear range from 1 fM-100 nM with detection limit of 0.79 fM under optimal experimental conditions. The performance of this aptaelectrode was also evaluated showing good selectivity, storage stability (15 days), reproducibility and reusability (up to 3 times). Furthermore, the applicability of the aptasensor for spiked serum samples showed recovery range from 92% to 97%.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais , Técnicas Eletroquímicas , Grafite/química , Nanopartículas Metálicas/química , Mucina-1/análise , Ácidos Carboxílicos/química , Ouro/química , Humanos , Tamanho da Partícula , Platina/química , Propriedades de Superfície
20.
Dalton Trans ; 49(6): 1736-1741, 2020 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-31967147

RESUMO

Platinum(iv) complexes with a heterocyclic ligand and an ancillary ligand have been investigated and applied for treating various tumour cell lines. Another application of the Pt(iv) complexes in forming peptide disulfide bonds was investigated in this work. For development of Pt(iv) complex chemistry for disulfide bond formation in peptides, two Pt(iv) complexes, [PtCl2(phen)(en)]Cl2 and [PtCl2(bpy)(en)]Cl2, were synthesized and characterized using elemental analysis, ESI-MS and NMR. Subsequently, they were investigated as oxidants for the formation of disulfide bonds in various peptides. Excellent purities and yields of disulfide-containing peptides were achieved when the reactions were carried out in aqueous solution. The reactions were completed rapidly in a wide range of pH values even in acidic medium at room temperature. An intramolecular disulfide bond was formed in each of the peptides in a solution containing two dithiol-containing peptides, making the Pt(iv) complexes useful for generating disulfide-containing peptide libraries. In addition, the two Pt(iv) complexes can be used as oxidants for the synthesis of disulfide bonds on a resin, which is a more convenient method to synthesize disulfide-containing peptides through automation.


Assuntos
Complexos de Coordenação/química , Dissulfetos/química , Compostos Organoplatínicos/química , Peptídeos/química , Técnicas de Química Sintética , Complexos de Coordenação/síntese química , Dissulfetos/síntese química , Ligantes , Compostos Organoplatínicos/síntese química , Peptídeos/síntese química , Platina/química
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