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1.
Molecules ; 26(15)2021 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-34361743

RESUMO

While investigating the possible synergistic effect of the conventional anticancer therapies, which, taken individually, are often ineffective against critical tumors, such as central nervous system (CNS) ones, the design of a theranostic nanovector able to carry and deliver chemotherapy drugs and magnetic hyperthermic agents to the target radiosensitizers (oxygen) was pursued. Alongside the original formulation of polymeric biodegradable oxygen-loaded nanostructures, their properties were fine-tuned to optimize their ability to conjugate therapeutic doses of drugs (doxorubicin) or antitumoral natural substances (curcumin). Oxygen-loaded nanostructures (diameter = 251 ± 13 nm, ζ potential = -29 ± 5 mV) were finally decorated with superparamagnetic iron oxide nanoparticles (SPIONs, diameter = 18 ± 3 nm, ζ potential = 14 ± 4 mV), producing stable, effective and non-agglomerating magnetic nanovectors (diameter = 279 ± 17 nm, ζ potential = -18 ± 7 mV), which could potentially target the tumoral tissues under magnetic driving and are monitorable either by US or MRI imaging.


Assuntos
Antibióticos Antineoplásicos/farmacologia , Quitosana/química , Hipertermia Induzida/métodos , Nanopartículas de Magnetita/química , Radiossensibilizantes/farmacologia , Nanomedicina Teranóstica/métodos , Antibióticos Antineoplásicos/química , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos da radiação , Meios de Contraste/síntese química , Meios de Contraste/farmacologia , Curcumina/química , Curcumina/farmacologia , Sulfato de Dextrana/química , Doxorrubicina/química , Doxorrubicina/farmacologia , Composição de Medicamentos/métodos , Humanos , Cinética , Nanopartículas de Magnetita/ultraestrutura , Oxigênio/química , Oxigênio/farmacologia , Radiossensibilizantes/síntese química
2.
Zool Res ; 42(5): 592-605, 2021 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-34387415

RESUMO

The large yellow croaker (Larimichthys crocea), which is an economically important mariculture fish in China, is often exposed to environmental hypoxia. Reactive oxygen species (ROS) homeostasis is essential for the maintenance of normal physiological conditions in an organism. Direct evidence that environmental hypoxia leads to ROS overproduction is scarce in marine fish. Furthermore, the sources of ROS overproduction in marine fish under hypoxic stress are poorly known. In this study, we investigated the effects of hypoxia on redox homeostasis in L. crocea and the impact of impaired redox homeostasis on fish. We first confirmed that hypoxia drove ROS production mainly via the mitochondrial electron transport chain and NADPH oxidase complex pathways in L. crocea and its cell line (large yellow croaker fry (LYCF) cells). We subsequently detected a marked increase in the antioxidant systems of the fish. However, imbalance between the pro-oxidation and antioxidation systems ultimately led to excessive ROS and oxidative stress. Cell viability showed a remarkable decrease while oxidative indicators, such as malondialdehyde, protein carbonylation, and 8-hydroxy-2 deoxyguanosine, showed a significant increase after hypoxia, accompanied by tissue damage. N-acetylcysteine (NAC) reduced ROS levels, alleviated oxidative damage, and improved cell viability in vitro. Appropriate uptake of ROS scavengers (e.g., NAC and elamipretide Szeto-Schiller-31) and inhibitors (e.g., apocynin, diphenylene iodonium, and 5-hydroxydecanoate) may be effective at overcoming hypoxic toxicity. Our findings highlight previously unstudied strategies of hypoxic toxicity resistance in marine fish.


Assuntos
Antioxidantes/metabolismo , Peixes/metabolismo , Estresse Oxidativo/fisiologia , Oxigênio/química , Oxigênio/metabolismo , Espécies Reativas de Oxigênio , Animais , Linhagem Celular , Sobrevivência Celular , Meio Ambiente , Homeostase , NADP
3.
Photochem Photobiol Sci ; 20(7): 843-857, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34216374

RESUMO

Photosensitizers of singlet oxygen exhibit three main types of reverse intersystem-crossing (RISC): thermally activated, triplet-triplet annihilation, and singlet oxygen feedback. RISC can be followed by delayed fluorescence (DF) emission, which can provide important information about the excited state dynamics in the studied system. An excellent model example is a widely used clinical photosensitizer Protoporphyrin IX, which manifests all three mentioned types of RISC and DF. Here, we estimated rate constants of individual RISC and DF processes in Protoporphyrin IX in dimethylformamide, and we showed how these affect triplet decays and DF signals under diverse experimental conditions, such as a varying oxygen concentration or excitation intensity. This provided a basis for a general discussion on guidelines for a more precise analysis of long-lived signals. Furthermore, it has been found that PpIX photoproducts and potential transient excited complexes introduce a new overlapping delayed luminescence spectral band with a distinct lifetime. These findings are important for design of more accurate biological oxygen sensors and assays based on DF and triplet lifetime.


Assuntos
Fluorescência , Hipóxia , Fármacos Fotossensibilizantes/metabolismo , Protoporfirinas/metabolismo , Humanos , Oxigênio/química , Oxigênio/metabolismo , Fármacos Fotossensibilizantes/química , Protoporfirinas/química
4.
Int J Mol Sci ; 22(13)2021 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-34202099

RESUMO

We performed ab initio numerical simulations with the density functional theory to investigate the variations in the band structure, optical absorption, and the reflectivity of vacancy-graphene doped with nitrogen, oxygen, and fluorine for different densities. We considered the density values 0.78%, 1.02%, 1.39%, 2.00%, 3.12%, 5.55%, and 12.5% for the vacancies and doping. In the infrared and visible ranges for all cases, vacancies included, there is a substantial increment in the absorption and reflectivity concerning graphene. The most significant changes are for fluorine and oxygen at a concentration of 12.5%.


Assuntos
Flúor/química , Grafite/química , Nitrogênio/química , Oxigênio/química , Análise Espectral , Elétrons , Estrutura Molecular , Nanopartículas/química
5.
Int J Mol Sci ; 22(12)2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-34203700

RESUMO

Fullerene is a nanosized carbon structure with potential drug delivery applications. We studied the bioeffects of a water-soluble fullerene derivative, fullerenol, with 10-12 oxygen groups (F10-12); its structure was characterized by IR and XPS spectroscopy. A bioluminescent enzyme system was used to study toxic and antioxidant effects of F10-12 at the enzymatic level. Antioxidant characteristics of F10-12 were revealed in model solutions of organic and inorganic oxidizers. Low-concentration activation of bioluminescence was validated statistically in oxidizer solutions. Toxic and antioxidant characteristics of F10-12 were compared to those of homologous fullerenols with a higher number of oxygen groups:F24-28 and F40-42. No simple dependency was found between the toxic/antioxidant characteristics and the number of oxygen groups on the fullerene's carbon cage. Lower toxicity and higher antioxidant activity of F24-28 were identified and presumptively attributed to its higher solubility. An active role of reactive oxygen species (ROS) in the bioeffects of F10-12 was demonstrated. Correlations between toxic/antioxidant characteristics of F10-12 and ROS content were evaluated. Toxic and antioxidant effects were related to the decrease in ROS content in the enzyme solutions. Our results reveal a complexity of ROS effects in the enzymatic assay system.


Assuntos
Antioxidantes/farmacologia , Fulerenos/farmacologia , Fulerenos/toxicidade , Oxigênio/química , Cinética , Luminescência , Oxirredução , Espécies Reativas de Oxigênio/metabolismo
6.
Chem Commun (Camb) ; 57(63): 7786-7789, 2021 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-34264259

RESUMO

Herein, we propose a dual-responsive fluorescent nanoprobe to visualize the cross-talk between O2 and adenosine triphosphate (ATP) in living cells. We hope it will be a helpful tool for the further understanding of cellular metabolism and further facilitating risk warning in the process of adaptation to consistent environmental pressures in premalignant lesions.


Assuntos
Trifosfato de Adenosina/metabolismo , Corantes Fluorescentes/metabolismo , Nanopartículas/metabolismo , Oxigênio/metabolismo , Trifosfato de Adenosina/química , Corantes Fluorescentes/química , Humanos , Células MCF-7 , Nanopartículas/química , Oxigênio/química
7.
Inorg Chem ; 60(16): 12392-12404, 2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34319113

RESUMO

A water-soluble strapped iron(III)tetraarylporphyrin (FeIIIPor-1) bearing two propylpyridinium groups at the side chains and a carboxylic acid group at the overhanging position of the strap was synthesized to mimic the function of myoglobin with the distal polar functionality in aqueous solution. FeIIIPor-1 forms a stable 1:1 inclusion complex with a per-O-methylated ß-cyclodextrin dimer having a pyridine linker (Py3OCD), providing a hydrophobic environment and a proximal fifth ligand to stabilize the O2-complex. The ferrous complex (FeIIPorCD-1) binds both O2 and CO in aqueous solution. The O2 and CO binding affinities (P1/2O2 and P1/2CO) and half-life time (t1/2) of the O2 complex of FeIIPorCD-1 are 6.3 and 0.021 Torr, and 7 h, respectively, at pH 7 and 25 °C. The control compound without the strap structure (FeIIPorCD-2) has similar oxygen binding characteristics (P1/2O2 = 8.0 Torr), but much higher CO binding affinity (P1/2CO = 3.8 × 10-4 Torr), and longer t1/2 (30 h). The O2 and CO kinetics indicate that the strapped structure in FeIIPorCD-1 inhibits the entrance of these gaseous ligands into the iron(II) center, as evidenced by lower konO2 and konCO values. Interestingly, the CO complex of FeIIPorCD-1 is significantly destabilized (relatively larger koffCO), while the koffO2 value is much smaller than that of FeIIPorCD-2, resulting in significantly increased O2/CO selectivity (reduced M value, where M = P1/2O2/P1/2CO = 320) in FeIIPorCD-1 compared to FeIIPorCD-2 (M = 21000).


Assuntos
Materiais Biomiméticos/química , Monóxido de Carbono/química , Ciclodextrinas/química , Mioglobina/química , Oxigênio/química , Porfirinas/química , Água/química , Concentração de Íons de Hidrogênio , Soluções , Temperatura
8.
Phys Chem Chem Phys ; 23(31): 16767-16775, 2021 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-34319324

RESUMO

Photosensing LOV (Light, Oxygen, Voltage) domains detect and respond to UVA/Blue (BL) light by forming a covalent adduct between the flavin chromophore and a nearby cysteine, via the decay of the flavin triplet excited state. LOV domains where the reactive cysteine has been mutated are valuable fluorescent tools for microscopy and as genetically encoded photosensitisers for reactive oxygen species. Besides being convenient tools for applications, LOV domains without the reactive cysteine (naturally occurring or engineered) can still be functionally photoactivated via formation of a neutral flavin radical. Tryptophans and tyrosines are held as the main partners as potential electron donors to the flavin excited states. In this work, we explore the relevance of aromatic amino acids in determining the photophysical features of the LOV protein Mr4511 from Methylobacterium radiotolerans by introducing point mutations into the C71S variant that does not form the covalent adduct. By using an array of spectroscopic techniques we measured the fluorescence quantum yields and lifetimes, the triplet yields and lifetimes, and the efficiency of singlet oxygen (SO) formation for eleven Mr4511 variants. Insertion of Trp residues at distances between 0.6 and 1.5 nm from the flavin chromophore results in strong quenching of the flavin excited triplet state and, at the shorter distances even of the singlet excited state. The mutation F130W (ca. 0.6 nm) completely quenches the singlet excited state, preventing triplet formation: in this case, even if the cysteine is present, the photo-adduct is not formed. Tyrosines are also quenchers for the flavin excited states, although not as efficient as Trp residues, as demonstrated with their substitution with the inert phenylalanine. For one of these variants, C71S/Y116F, we found that the quantum yield of formation for singlet oxygen is 0.44 in aqueous aerobic solution, vs 0.17 for C71S. Based on our study with Mr4511 and on literature data for other LOV domains we suggest that Trp and Tyr residues too close to the flavin chromophore (at distances less than 0.9 nm) reduce the yield of photoproduct formation and that introduction of inert Phe residues in key positions can help in developing efficient, LOV-based photosensitisers.


Assuntos
Aminoácidos Aromáticos/química , Proteínas de Bactérias/química , Luz , Oxigênio/química , Methylobacterium/química , Processos Fotoquímicos
9.
Int J Mol Sci ; 22(14)2021 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-34298905

RESUMO

To evaluate the antioxidant activity of potential synthetic enzyme mimetics, we prepared new five copper(II) complexes via a self-assembly method and named them [Cu(2-(HOCH2)py)3](ClO4)2 (1), [Cu(2-(HOCH2)py)2(H2O)2]SiF6 (2), [Cu2(2-(HOCH2CH2)py)2(2-(OCH2CH2)py)2](ClO4)2 (3), [Cu(pyBIm)3](BF4)2·1.5H2O (4) and [Cu(py2C(OH)2)2](ClO4)2 (5). The synthetic protocol involved N,O- or N,N-donors: 2-(hydroxymethyl)pyridine (2-(HOCH2)py), 2-(hydroxyethyl)pyridine (2-(HOCH2CH2)py), 2-(2-pyridyl)benzimidazole (pyBIm), di(2-pyridyl)ketone (py2CO). The obtained Cu(II) complexes were fully characterised by elemental analysis, FTIR, EPR, UV-Vis, single-crystal X-ray diffraction and Hirshfeld surface analysis. Crystallographic and spectroscopic analyses confirmed chromophores of both monomeric ({CuN3O3} (1), {CuN2O4} (2), {CuN6} (4), {CuN4O2} (5)) and dimeric complex ({CuN2O3} (3)). Most of the obtained species possessed a distorted octahedral environment, except dimer 3, which consisted of two copper centres with square pyramidal geometries. The water-soluble compounds (1, 3 and 5) were selected for biological testing. The results of the study revealed that complex 1 in solutions displayed better radical scavenging activity than complexes 3, 5 and free ligands. Therefore, complex 1 has been selected for further studies to test its activity as an enzyme mimetic. The chosen compound was tested on the erythrocyte lysate of two groups of patients after undergoing chemotherapy and chemoradiotherapy. The effect of the tested compound (1) on enzyme activity levels (TAS, SOD and CAT) suggests that the selected complex can be treated as a functional mimetic of the enzymes.


Assuntos
Cobre/química , Sequestradores de Radicais Livres/química , Metaloproteínas/química , Nitrogênio/química , Oxigênio/química , Benzimidazóis/química , Domínio Catalítico/fisiologia , Complexos de Coordenação/química , Cristalografia por Raios X/métodos , Ligantes , Estrutura Molecular , Piridinas/química
10.
Phys Chem Chem Phys ; 23(29): 15557-15563, 2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34259248

RESUMO

The deactivation of singlet oxygen, the lowest electronic excited state of molecular oxygen, by proteins is usually described through the interaction of singlet oxygen with certain amino acids. Changes in accessibility of these amino acids influence the quenching rate and the phosphorescence kinetics of singlet oxygen. In the cellular environment, however, numerous proteins with covalently bound or encapsulated cofactors are present. These cofactors could also influence the deactivation of singlet oxygen, and these have received little attention. To confront this issue, we used cytochrome c (cyt c) and apocytochrome c (apocyt c) to illustrate how the heme prosthetic group influences the rate constant of singlet oxygen deactivation upon acidic pH-induced conformational change of cyt c. Photo-excited flavin mononucleotide (FMN) was used to produce singlet oxygen. Our data show that the heme group has a significant and measurable effect on singlet oxygen quenching when the heme is exposed to solvents and is therefore more accessible to singlet oxygen. The effect of amino acids and heme accessibility on the FMN triplet state deactivation was also investigated.


Assuntos
Citocromos c/química , Mononucleotídeo de Flavina/química , Heme/química , Oxigênio Singlete/química , Sequência de Aminoácidos , Citocromos c/metabolismo , Heme/metabolismo , Cinética , Modelos Moleculares , Oxigênio/química , Fotoquímica , Ligação Proteica , Oxigênio Singlete/metabolismo
11.
Inorg Chem ; 60(12): 8710-8721, 2021 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-34110143

RESUMO

A handful of oxygen-activating enzymes has recently been found to contain Fe/Mn active sites, like Class 1c ribonucleotide reductases and R2-like ligand-binding oxidase, which are closely related to their better characterized diiron cousins. These enzymes are proposed to form high-valent intermediates with Fe-O-Mn cores. Herein, we report the first examples of synthetic Fe/Mn complexes that mimic doubly bridged intermediates proposed for enzymatic oxygen activation. Fe K-edge extended X-ray absorption fine structure (EXAFS) analysis has been used to characterize the structures of each of these compounds. Linear compounds accurately model the Fe···Mn distances found in Fe/Mn proteins in their resting states, and doubly bridged diamond core compounds accurately model the distances found in high-valent biological intermediates. Unlike their diiron analogues, the paramagnetic nature of Fe/Mn compounds can be analyzed by EPR, revealing S = 1/2 signals that reflect antiferromagnetic coupling between the high-spin Fe(III) and Mn(III) units of heterobimetallic centers. These compounds undergo electron transfer with various ferrocenes, linear compounds being capable of oxidizing diacetyl ferrocene, a weak reductant, and diamond core compounds being capable of oxidizing acetyl ferrocene. Diamond core compounds can also perform HAT reactions from substrates with X-H bonds with bond dissociation free energies (BDFEs) up to 75 kcal/mol and are capable of oxidizing TEMPO-H at rates of 0.32-0.37 M-1 s-1, which are comparable to those reported for some mononuclear FeIII-OH and MnIII-OH compounds. However, such reactivity is not observed for the corresponding diiron compounds, a difference that Nature may have taken advantage of in evolving enzymes with heterobimetallic active sites.


Assuntos
Complexos de Coordenação/metabolismo , Compostos Férricos/metabolismo , Manganês/metabolismo , Ribonucleotídeo Redutases/metabolismo , Sítios de Ligação , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Compostos Férricos/química , Manganês/química , Modelos Moleculares , Estrutura Molecular , Oxigênio/química , Oxigênio/metabolismo , Ribonucleotídeo Redutases/química
12.
Nature ; 594(7861): 66-70, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-34079137

RESUMO

The concentration of dissolved oxygen in aquatic systems helps to regulate biodiversity1,2, nutrient biogeochemistry3, greenhouse gas emissions4, and the quality of drinking water5. The long-term declines in dissolved oxygen concentrations in coastal and ocean waters have been linked to climate warming and human activity6,7, but little is known about the changes in dissolved oxygen concentrations in lakes. Although the solubility of dissolved oxygen decreases with increasing water temperatures, long-term lake trajectories are difficult to predict. Oxygen losses in warming lakes may be amplified by enhanced decomposition and stronger thermal stratification8,9 or oxygen may increase as a result of enhanced primary production10. Here we analyse a combined total of 45,148 dissolved oxygen and temperature profiles and calculate trends for 393 temperate lakes that span 1941 to 2017. We find that a decline in dissolved oxygen is widespread in surface and deep-water habitats. The decline in surface waters is primarily associated with reduced solubility under warmer water temperatures, although dissolved oxygen in surface waters increased in a subset of highly productive warming lakes, probably owing to increasing production of phytoplankton. By contrast, the decline in deep waters is associated with stronger thermal stratification and loss of water clarity, but not with changes in gas solubility. Our results suggest that climate change and declining water clarity have altered the physical and chemical environment of lakes. Declines in dissolved oxygen in freshwater are 2.75 to 9.3 times greater than observed in the world's oceans6,7 and could threaten essential lake ecosystem services2,3,5,11.


Assuntos
Lagos/química , Oxigênio/análise , Oxigênio/metabolismo , Temperatura , Animais , Mudança Climática , Ecossistema , Oceanos e Mares , Oxigênio/química , Fitoplâncton/metabolismo , Solubilidade , Fatores de Tempo
13.
Chem Commun (Camb) ; 57(57): 7027-7030, 2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-34165482

RESUMO

Magnetic interactions within Mn-(µ-O)2-Mn pairs are crucial to the function of some essential enzymes and catalysts, but their nature is unclear. Neutron diffraction reveals that similar units in BiMnPO5 show ferromagnetic coupling which has been rationalized by density functional theory modelling and calculations of magnetic exchange energies. The results are important to many solid state and biological systems.


Assuntos
Bismuto/química , Magnetismo , Manganês/química , Catálise , Teoria da Densidade Funcional , Enzimas/química , Enzimas/metabolismo , Conformação Molecular , Difração de Nêutrons , Oxigênio/química
14.
Molecules ; 26(11)2021 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-34072265

RESUMO

Though siRNA-based therapy has achieved great progress, efficient siRNA delivery remains a challenge. Here, we synthesized a copolymer PAsp(-N=C-PEG)-PCys-PAsp(DETA) consisting of a poly(aspartate) block grafted with comb-like PEG side chains via a pH-sensitive imine bond (PAsp(-N=C-PEG) block), a poly(l-cysteine) block with a thiol group (PCys block), and a cationic poly(aspartate) block grafted with diethylenetriamine (PAsp(DETA) block). The cationic polymers efficiently complexed siRNA into polyplexes, showing a sandwich-like structure with a PAsp(-N=C-PEG) out-layer, a crosslinked PCys interlayer, and a complexing core of siRNA and PAsp(DETA). Low pH-triggered breakage of pH-sensitive imine bonds caused PEG shedding. The disulfide bond-crosslinking and pH-triggered PEG shedding synergistically decreased the polyplexes' size from 75 nm to 26 nm. To neutralize excessive positive charges and introduce the targeting ligand, the polyplexes without a PEG layer were coated with an anionic copolymer modified with the targeting ligand lauric acid. The resulting polyplexes exhibited high transfection efficiency and lysosomal escape capacity. This study provides a promising strategy to engineer the size and surface of polyplexes, allowing long blood circulation and targeted delivery of siRNA.


Assuntos
Polímeros/química , RNA Interferente Pequeno/metabolismo , Ânions , Cátions , Sobrevivência Celular , Reagentes para Ligações Cruzadas/química , Citoplasma/metabolismo , Dissulfetos , Sistemas de Liberação de Medicamentos , Humanos , Concentração de Íons de Hidrogênio , Ácidos Láuricos/química , Ligantes , Espectroscopia de Ressonância Magnética , Oxigênio/química , Tamanho da Partícula , Polietilenoglicóis/química , Espectroscopia de Infravermelho com Transformada de Fourier , Células THP-1
15.
Int J Biol Macromol ; 184: 20-28, 2021 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-34118287

RESUMO

This study aimed to investigate the use of glycol chitosan (GC) for the synthesis of MnO2 nanoparticles (NPs) and to evaluate whether the prepared GC-MnO2 NPs enhance the light-triggered photodynamic effects of chlorin e6 (Ce6) via the generation of oxygen and alleviation of hypoxia in lipopolysaccharide (LPS)-activated macrophages (RAW 264.7), which produce excessive amounts of reactive oxygen species (ROS). GC-MnO2 NPs were synthesized by a simple reaction between GC and KMnO4 in water. The prepared GC-MnO2 NPs were spherical in shape, with a mean diameter of approximately 60 nm. The particles effectively generated oxygen via H2O2-induced degradation under hypoxic conditions, which led to an increase in the singlet oxygen levels upon laser irradiation. Furthermore, GC-MnO2 NPs significantly enhanced the light-triggered photodynamic effects of Ce6 on activated macrophages under hypoxic conditions, as shown by the increased levels of cell death and cell membrane damage in activated macrophages. Therefore, these results suggest that GC can be used as an alternative natural polymer for the synthesis of MnO2 NPs and that oxygen-generating GC-MnO2 NPs enhance the light-triggered photodynamic effects of Ce6 on activated macrophages by alleviating hypoxia.


Assuntos
Quitosana/química , Peróxido de Hidrogênio/metabolismo , Ativação de Macrófagos/efeitos dos fármacos , Compostos de Manganês/química , Óxidos/química , Oxigênio/química , Porfirinas/farmacologia , Animais , Morte Celular , Hipóxia Celular , Lipopolissacarídeos/efeitos adversos , Terapia com Luz de Baixa Intensidade , Camundongos , Nanopartículas , Tamanho da Partícula , Fotoquimioterapia , Porfirinas/química , Células RAW 264.7 , Água/química
16.
ACS Appl Mater Interfaces ; 13(27): 31474-31484, 2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34192459

RESUMO

Owing to several key attributes, diamond is an attractive candidate material for neural interfacing electrodes. The emergence of additive-manufacturing (AM) of diamond-based materials has addressed multiple challenges associated with the fabrication of diamond electrodes using the conventional chemical vapor deposition (CVD) approach. Unlike the CVD approach, AM methods have enabled the deposition of three-dimensional diamond-based material at room temperature. This work demonstrates the feasibility of using laser metal deposition to fabricate diamond-titanium hybrid electrodes for neuronal interfacing. In addition to exhibiting a high electrochemical capacitance of 1.1 mF cm-2 and a low electrochemical impedance of 1 kΩ cm2 at 1 kHz in physiological saline, these electrodes exhibit a high degree of biocompatibility assessed in vitro using cortical neurons. Furthermore, surface characterization methods show the presence of an oxygen-rich mixed-phase diamond-titanium surface along the grain boundaries. Overall, we demonstrated that our unique approach facilitates printing biocompatible titanium-diamond site-specific coating-free conductive hybrid surfaces using AM, which paves the way to printing customized electrodes and interfacing implantable medical devices.


Assuntos
Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Encéfalo/citologia , Diamante/química , Neurônios/efeitos dos fármacos , Impressão Tridimensional , Titânio/química , Animais , Impedância Elétrica , Neurônios/citologia , Oxigênio/química , Propriedades de Superfície
17.
Molecules ; 26(11)2021 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-34072092

RESUMO

Heme and nonheme-type flavone synthase enzymes, FS I and FS II are responsible for the synthesis of flavones, which play an important role in various biological processes, and have a wide range of biomedicinal properties including antitumor, antimalarial, and antioxidant activities. To get more insight into the mechanism of this curious enzyme reaction, nonheme structural and functional models were carried out by the use of mononuclear iron, [FeII(CDA-BPA*)]2+ (6) [CDA-BPA = N,N,N',N'-tetrakis-(2-pyridylmethyl)-cyclohexanediamine], [FeII(CDA-BQA*)]2+ (5) [CDA-BQA = N,N,N',N'-tetrakis-(2-quinolilmethyl)-cyclohexanediamine], [FeII(Bn-TPEN)(CH3CN)]2+ (3) [Bn-TPEN = N-benzyl-N,N',N'-tris(2-pyridylmethyl)-1,2-diaminoethane], [FeIV(O)(Bn-TPEN)]2+ (9), and manganese, [MnII(N4Py*)(CH3CN)]2+ (2) [N4Py* = N,N-bis(2-pyridylmethyl)-1,2-di(2-pyridyl)ethylamine)], [MnII(Bn-TPEN)(CH3CN)]2+ (4) complexes as catalysts, where the possible reactive intermediates, high-valent FeIV(O) and MnIV(O) are known and well characterised. The results of the catalytic and stoichiometric reactions showed that the ligand framework and the nature of the metal cofactor significantly influenced the reactivity of the catalyst and its intermediate. Comparing the reactions of [FeIV(O)(Bn-TPEN)]2+ (9) and [MnIV(O)(Bn-TPEN)]2+ (10) towards flavanone under the same conditions, a 3.5-fold difference in reaction rate was observed in favor of iron, and this value is three orders of magnitude higher than was observed for the previously published [FeIV(O)(N2Py2Q*)]2+ [N,N-bis(2-quinolylmethyl)-1,2-di(2-pyridyl)ethylamine] species.


Assuntos
Ferro/química , Manganês/química , Oxigenases de Função Mista/química , Antimaláricos/química , Antineoplásicos/química , Antioxidantes/química , Catálise , Sistema Enzimático do Citocromo P-450/química , Flavanonas/química , Flavonas/química , Radicais Livres , Íons , Cinética , Ligantes , Modelos Moleculares , Conformação Molecular , Oxirredução , Oxigênio/química , Espectrofotometria Ultravioleta , Água/química
18.
Molecules ; 26(11)2021 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-34072101

RESUMO

The tannery industry is one of the economic sectors that contributes to the development of different countries. Globally, Europe and Asia are the main producers of this industry, although Latin America and Africa have been growing considerably in recent years. With this growth, the negative environmental impacts towards different ecosystem resources as a result of the discharges of recalcitrated pollutants, have led to different investigations to generate alternative solutions. Worldwide, different technologies have been studied to address this problem, biological and physicochemical processes have been widely studied, presenting drawbacks with some recalcitrant compounds. This review provides a context on the different existing technologies for the treatment of tannery wastewater, analyzing the physicochemical composition of this liquid waste, the impact it generates on human health and ecosystems and the advances in the different existing technologies, focusing on advanced oxidation processes and the use of microalgae. The coupling of advanced oxidation processes with biological processes, mainly microalgae, is seen as a viable biotechnological strategy, not only for the removal of pollutants, but also to obtain value-added products with potential use in the biorefining of the biomass.


Assuntos
Resíduos Industriais/análise , Microalgas/metabolismo , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/química , Biocombustíveis , Análise da Demanda Biológica de Oxigênio , Biomassa , Biotecnologia , Cianobactérias , Ecossistema , Eletroquímica , Geografia , Metais Pesados , Oxirredução , Oxigênio/química , Curtume , Purificação da Água/métodos
19.
Molecules ; 26(11)2021 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-34067394

RESUMO

Pharmaceuticals are found in waterbodies worldwide. Conventional sewage treatment plants are often not able to eliminate these micropollutants. Hence, Advanced Oxidation Processes (AOPs) have been heavily investigated. Here, metoprolol is exposed to UV irradiation, hydrogen peroxide, and ozonation. Degradation was analyzed using chemical kinetics both for initial and secondary products. Photo-induced irradiation enhanced by hydrogen peroxide addition accelerated degradation more than ozonation, leading to complete elimination. Degradation and transformation products were identified by high-performance liquid-chromatography coupled to high-resolution higher-order mass spectrometry. The proposed structures allowed to apply Quantitative Structure-Activity Relationship (QSAR) analysis to predict ecotoxicity. Degradation products were generally associated with a lower ecotoxicological hazard to the aquatic environment according to OECD QSAR toolbox and VEGA. Comparison of potential structural isomers suggested forecasts may become more reliable with larger databases in the future.


Assuntos
Ecotoxicologia , Metoprolol/análise , Ozônio/química , Relação Quantitativa Estrutura-Atividade , Esgotos/química , Águas Residuárias/química , Poluentes Químicos da Água/análise , Algoritmos , Reatores Biológicos , Cromatografia Líquida de Alta Pressão , Ecotoxicologia/métodos , Monitoramento Ambiental/métodos , Peróxido de Hidrogênio/química , Concentração de Íons de Hidrogênio , Cinética , Metoprolol/química , Oxigênio/química , Fotoquímica , Fotólise , Software , Raios Ultravioleta , Poluentes Químicos da Água/química
20.
J Phys Chem Lett ; 12(25): 5925-5931, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34156863

RESUMO

Resonant stimulated X-ray Raman spectroscopy of the bimetallic [MnIIIMnIV(µ-O)2(µ-OAC)(tacn)2]2+ manganese complex is investigated in a simulation study. Essential biological processes, including water oxidation in photosynthesis, involve charge transfer between manganese sites of different oxidation states. We study a prototypical binuclear mixed-valence transition-metal complex with two Mn atoms in different oxidation states surrounded by ligand structures and employ a pump-probe sequence of resonant X-ray Raman excitations to follow the charge transfer occurring in the molecule. This allows us to generate and monitor valence-electron wave packets at selected regions in the molecule by exploiting element-specific core-excited states. A two-color protocol is presented, with pump and probe pulses tuned to the Mn and N K-edges. A natural orbital decomposition allows the visualization of the electron dynamics underlying the signal.


Assuntos
Complexos de Coordenação/química , Manganês/química , Análise Espectral Raman , Eletroquímica , Ligantes , Oxigênio/química , Água/química , Raios X
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