Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.488
Filtrar
1.
Chemosphere ; 346: 140567, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38303386

RESUMO

In the contemporary context, executing light-oxidant- and reductant-driven reactions in solution-phase processes remains challenging mainly due to the lack of general tools for understanding the reactive potential of nano-functional catalysts. In this study, dual-active nanometals (Au and Cu doped with Au) capped within soy lecithin (SL), were developed and characterized, combining flexibility with the catalytic advantages and stability of liquid-phase catalysts. The as-synthesized SL-Au (LG) and SL-Au-Cu (LGC) catalysts were efficiently degraded rhodamine B (RB, 100%) in the presence of H2O2 under light irradiation (350 W lamp) at wide pH range (3-7) within 4.5 h and p-nitrophenol (p-NP, >90% degradation at pH 7) in the presence of NaBH4 under normal stirring with slower kinetics (∼72 h). RB degradation followed a pseudo-second-order kinetic model with a higher r2, and p-NP degradation followed first-order kinetics. The active sites embedded within the structural order of SL arrangement displayed elevated catalytic activity, which was further enhanced by the movement of intermediate/excited states and charged elements within the metal suspended in the phospholipid (LG and LGC). The self-regulating tunability of the physicochemical characteristics of these catalysts provides a convenient and generalizable platform for the transformation of modern dual-active (redox) catalysts into dynamic homogeneous equivalents.


Assuntos
Peróxido de Hidrogênio , Peróxidos , Peróxido de Hidrogênio/química , Boroidretos , Fosfolipídeos , Oxirredução , Suspensões
2.
Biomed Phys Eng Express ; 10(2)2024 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-38237173

RESUMO

Silver nanoparticles (AgNPs) in the form of nanospheres from a few nm to 100 nm in diameter were synthesized in a controlled manner using a combination of two reducing agents: sodium borohydride (SBH) and trisodium citrate (TSC). The influence of the size of AgNPs on antibacterial activity was investigated with different concentrations of AgNPs on two types of bacteria:Pseudomonas aeruginosa(PA) andStaphylococcus aureusresistant (SA) while the positive control wasAmpicillin (Amp)50µg/ml and the negative control was water. AgNPs were investigated for morphology, size and size distribution using transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. The optical properties of the AgNPs were investigated by recording their UV-vis absorption spectra. The antimicrobial activity of AgNPs was determined using the disc diffusion method. The results showed that the antibacterial ability of AgNPs depends on both concentration and particle size. With a particle concentration of 50µg ml-1, the antibacterial ability is the best. The smaller the particle size, the higher the antibacterial ability. The simultaneous use of two reducing agents TSC and SBH is the novelty of the article to synthesize AgNPs particles that are uniform in shape and size while controlling the particle size. On that basis, their antibacterial performance is increased.


Assuntos
Boroidretos , Nanopartículas Metálicas , Prata , Substâncias Redutoras , Escherichia coli , Antibacterianos/farmacologia
3.
J Hazard Mater ; 465: 133338, 2024 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-38150762

RESUMO

Environmental monitoring of pesticide residues in crops is essential for both food safety and environmental protection. Traditional methodologies face challenges due to the interference of endogenous compounds in peel and pulp tissues, often being invasive, labor-intensive, and inadequate for real-time observation of hazardous substance distribution. In this study, dynamic borohydride-reduced nanoparticles were employed as enhanced substrates. For the first time, surface-enhanced Raman spectroscopy (SERS) imaging was harnessed to enable whole-process visual detection of pesticide residues. The developed method is both stable and sensitive, boasting a detection lower limit below 1 pg/mL, coupled with robust quantitative analytical capabilities. This technique was successfully employed to detect residue signals across various crops and fruit juices. Furthermore, SERS imaging was utilized to map the distribution of pesticide residues from the exterior to the interior of fruits and vegetables. Vertex component analysis further refined the process by mitigating interference from plant autofluorescence. Collectively, this innovative strategy facilitates comprehensive pesticide residue monitoring, offering a potent tool for controlling hazardous substances in crops. Its potential applications extend beyond food safety, holding significant promise for sustainable agricultural production and enhanced environmental safeguarding.


Assuntos
Nanopartículas Metálicas , Resíduos de Praguicidas , Resíduos de Praguicidas/análise , Prata/química , Boroidretos , Análise Espectral Raman/métodos , Nanopartículas Metálicas/química
4.
Mikrochim Acta ; 190(12): 480, 2023 11 23.
Artigo em Inglês | MEDLINE | ID: mdl-37996711

RESUMO

A creatively designed novel two-step enhancement technique is presented in which B vitamin molecules are dynamically adsorbed onto the surface of silver nanoparticles by sodium borohydride, followed by local plasmon resonance in the presence of cations (calcium ions), ultimately achieving synergistic chemical and physical enhancement on the same molecule and constructing a "surface hot spots" two-step enhancement platform for vitamin detection. The Raman signal of the promoted vitamin molecule is enhanced by nine orders of magnitude. In a subsequent study it was observed that the vitamin B2 molecules were in a near-vertical image on the surface of the silver nanoparticles, which may also contribute to the Raman signal enhancement. Combined with deep learning techniques, the method has been successfully applied to the detection of B vitamins in body fluids. As an accurate, rapid, reproducible, non-invasive, and versatile assay platform, it holds great promise for the intelligent identification of trace B molecules in food, pharmaceuticals, and the human body.


Assuntos
Nanopartículas Metálicas , Complexo Vitamínico B , Humanos , Análise Espectral Raman/métodos , Nanopartículas Metálicas/química , Prata/química , Boroidretos
5.
Sci Rep ; 13(1): 8152, 2023 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-37208391

RESUMO

A comparative assessment of AgNPs synthesized through three different routes viz. clove bud extract mediated AgNPs, sodium borohydride AgNPs and Glutathione (GSH) capped AgNPs for antioxidant and mosquito larvicidal activities was the major focus of the present study. The nanoparticles were characterized using UV-VIS spectrophotometry, dynamic light scattering (DLS), X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR) analysis. Characterization studies revealed the synthesis of stable, crystalline AgNPs measuring 28 nm, 7 nm and 36 nm for green, chemical and GSH-capped AgNPs respectively. FTIR analysis exhibited the surface functional moieties that were responsible for reduction, capping and stabilizing AgNPs. Antioxidant activity was found to be 74.11%, 46.62% and 58.78% for clove, borohydride and GSH-capped AgNPs respectively. Mosquito larvicidal bioactivity of AgNPs against Aedes aegypti IIIrd instar larvae depicted clove AgNPs being most effective (LC50-4.9 ppm, LC90-30.2 ppm) followed by GSH-capped (LC50-20.13 ppm, LC90-46.63 ppm) and borohydride AgNPs (LC50-13.43 ppm, LC90-160.19 ppm) after 24 h. Toxicity screening against aquatic model Daphnia magna revealed Clove mediated and GSH-capped AgNPs to be safer as compared to the borohydride AgNPs. It may be envisaged that green and capped AgNPs may be further explored for diverse biomedical and therapeutic applications.


Assuntos
Aedes , Anopheles , Inseticidas , Nanopartículas Metálicas , Animais , Antioxidantes/farmacologia , Antioxidantes/análise , Prata/química , Boroidretos , Nanopartículas Metálicas/química , Inseticidas/química , Extratos Vegetais/química , Folhas de Planta/química , Glutationa/análise , Larva
6.
Appl Radiat Isot ; 198: 110818, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37196433

RESUMO

BNCT is considered to be a promising method for the treatment of malignant tumors, which ensures the selective destruction of malignant tumor cells by accumulating non-radioactive atomic boron-10 nuclei in them and subsequent irradiation with neutrons. As a result of the absorption of a neutron by boron, a nuclear reaction occurs with the release of energy in a cell containing boron, which leads to its death. To date, two drugs for targeted delivery of boron, boronophenylalanine and sodium borocaptate, have been developed, which ensures selective accumulation of boron in a number of tumors, and a number of charged particle accelerators with neutron-generating targets and with neutron beam shaping assemblies have been developed providing the quality of the neutron beam required for therapy. The paper presents a critical analysis of the methods used to form a therapeutic neutron beam and proposes a new concept of a neutron beam shaping assembly, supported by the results of numerical simulation validated by in-phantom measurements.


Assuntos
Terapia por Captura de Nêutron de Boro , Neoplasias , Animais , Terapia por Captura de Nêutron de Boro/métodos , Boro , Neoplasias/tratamento farmacológico , Nêutrons , Boroidretos
7.
Chem Commun (Camb) ; 59(47): 7182-7195, 2023 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-37184074

RESUMO

Atomically precise clusters of group 11 metals (Cu, Ag, and Au) attract considerable attention owing to their remarkable structure and fascinating properties. One of the unique subclasses of these clusters is based on dichalcophosphate ligands of [(RO)2PE2]- type (E = S or Se, and R = alkyl). These ligands successfully stabilise the most diverse Cu, Ag, and Au clusters and superatoms, spanning from simple ones to amazing assemblies featuring unusual structural and bonding patterns. It is noteworthy that such complicated clusters are assembled directly from cheap and simple reagents, metal(I) salts and dichalcophosphate anions. This reaction, when performed in the presence of a hydride or other anion sources, or foreign metal ions, results in hydrido- or anion-templated homo- or heteronuclear structures. In this feature article, we survey the recent advances in this exciting field, highlighting the powerful synthetic capabilities of the system "a metal(I) salt - [(RO)2PX2]- ligands - a templating anion or borohydride" as an inexhaustible platform for the creation of new atomically precise clusters, superatoms, and nanoalloys.


Assuntos
Metais , Cloreto de Sódio , Ligantes , Boroidretos
8.
Int J Pharm ; 636: 122825, 2023 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-36921740

RESUMO

In current study, a new remotely controlled drug delivery, radio-sensitizing, and photothermal therapy agent based on thioglycolic acid modified bismuth nanosheets is thoroughly evaluated. Bismuth nanosheets were synthesized using sodium borohydride (NaBH4) and Tween 20 through low energy (400 W) sonication within 2 h. The resultant nanosheets were 40-60 nm in size and 1-3 atomic layers in thickness. The morphological and structural characteristics of the nanosheets were studied using transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Raman spectroscopy and ultraviolet spectroscopy. The surface of the nanosheets was modified using thioglycolic acid, which resulted in enhanced Mitomycin C loading capacity to 274.35% and circumvented the burst drug release due to the improved electrostatic interactions. At pH 7.4 and 5.0, the drug release was significantly boosted from 45.1 to 69.8%, respectively. Thioglycolic acid modified bismuth nanosheets under 1064 nm laser irradiation possessed photothermal conversion efficiency of η=51.4% enabling a temperature rise of 24.9 °C at 100 µg/ml in 5 min. The combination of drug delivery, photothermal therapy, and radio-sensitization greatly damaged the MDA-MB-231 cells through apoptosis and diminished their colony forming.


Assuntos
Hipertermia Induzida , Neoplasias de Mama Triplo Negativas , Humanos , Doxorrubicina , Mitomicina , Boroidretos , Fototerapia/métodos , Bismuto , Sódio , Hipertermia Induzida/métodos
9.
J Radiat Res ; 64(2): 399-411, 2023 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-36763853

RESUMO

Human head and neck squamous cell carcinoma cells transfected with mutant TP53 (SAS/mp53) or neo vector (SAS/neo) were inoculated subcutaneously into left hind legs of nude mice. After the subcutaneous administration of a 10B-carrier, boronophenylalanine-10B (BPA) or sodium mercaptododecaborate-10B (BSH), at two separate concentrations, the 10B concentrations in tumors were measured using γ-ray spectrometry. The tumor-bearing mice received 5-bromo-2'-deoxyuridine (BrdU) continuously to label all intratumor proliferating (P) tumor cells, then were administered with BPA or BSH. Subsequently, the tumors were irradiated with reactor neutron beams during the time of which 10B concentrations were kept at levels similar to each other. Following irradiation, cells from some tumors were isolated and incubated with a cytokinesis blocker. The responses of BrdU-unlabeled quiescent (Q) and total (= P + Q) tumor cells were assessed based on the frequencies of micronucleation using immunofluorescence staining for BrdU. In both SAS/neo and SAS/mp53 tumors, the compound biological effectiveness (CBE) values were higher in Q cells and in the use of BPA than total cells and BSH, respectively. The higher the administered concentrations were, the smaller the CBE values became, with a clearer tendency in SAS/neo tumors and the use of BPA than in SAS/mp53 tumors and BSH, respectively. The values for BPA that delivers into solid tumors more dependently on uptake capacity of tumor cells than BSH became more alterable. Tumor micro-environmental heterogeneity might partially influence on the CBE value. The CBE value can be regarded as one of the indices showing the level of intratumor heterogeneity.


Assuntos
Terapia por Captura de Nêutron de Boro , Carcinoma de Células Escamosas , Neoplasias de Cabeça e Pescoço , Animais , Camundongos , Humanos , Bromodesoxiuridina/análise , Carcinoma de Células Escamosas/radioterapia , Carcinoma de Células Escamosas/patologia , Terapia por Captura de Nêutron de Boro/métodos , Camundongos Nus , Compostos de Boro/uso terapêutico , Boroidretos/química , Compostos de Sulfidrila , Proteína Supressora de Tumor p53
10.
Talanta ; 252: 123897, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36067699

RESUMO

This work proposes an automated strategy for the inorganic selenium speciation in infusion tea samples, employing an MSFIA-CVG-AFS system and sodium tetrahydroborate for chemical vapor generation. The selenium total is determined after an online prereduction step of selenium (VI) to selenium (IV) in alkaline media, using a UV reactor with a 15 W Hg lamp. Selenium (IV) is quantified directly on the sample, and selenium (VI) is determined by the difference between the total selenium and selenium (IV) concentrations. The optimization of the chemical parameters: hydrochloric acid - hydrobromide acid solution concentration, potassium iodide concentration, sodium hydroxide concentration, and sodium tetrahydroborate concentration was performed using a (24-1) two-level fractional factorial design. The validation parameters were determined for total selenium and selenium (IV), and the results found were: limits of detection and quantification of 0.05 and 0.18 µg L-1, respectively; a linear range of 0.18-5.0 µg L-1, precision expressed as the relative standard deviation of 2.1% for a sample number of 10, for both analytes. The system allows the speciation analysis with an injection throughput of 15 injections per hour. This analytical method was applied for inorganic selenium speciation in nine infusions of tea samples purchased commercially in supermarkets in Palma de Mallorca City, Spain. The concentrations of selenium (IV) and total selenium varied from 0.2 to 0.6 µg L-1 and 0.4-2.0 µg L-1, respectively. The accuracy method was evaluated using spike tests, and the recoveries achieved varied from 91 to 111%.


Assuntos
Selênio , Selênio/análise , Espectrometria de Fluorescência , Boroidretos , Chá , Espectrofotometria Atômica/métodos
11.
Opt Express ; 30(26): 47026-47037, 2022 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-36558640

RESUMO

Cigarette smoke is one of the six major pollution sources in the room air. It contains large number of particles with size less than 10 nm. There exist carbon dots (CDs) in cigarette smoke which have strong fluorescence and with good bio-compatibility and low toxicity. CDs in cigarette smoke can be applied in bio-imaging which has great potential applications in the integration of cancer diagnosis and treatment. In this paper, CDs were extracted from cigarette smoke. Then, sodium borohydride was added to CDs aqueous solution for reduction and the reduced CDs (R-CDs) were used for biological cell imaging. The results indicate that the CDs with the particle size <10 nm in cigarette smoke are self-assembled by the polymerizated polycyclic aromatic hydrocarbons (PAHs) and ammonium nitrite which are disk nano-structure composed of sp2/sp3 carbon and oxygen/nitrogen groups or polymers. Sodium borohydride can reduce the carbonyl group on the surface of CDs to hydroxyl group and increase the ratio of the Na 1s ratio of the CDs from 1.86 to 7.42. The CDs can emit blue fluorescence under ultraviolet irradiation. After reduction, the R-CDS have the intensity of fluorescence 7.2 times than before and the fluorescence quantum yield increase from 6.13% to 8.86%. The photoluminescence (PL) wavelength of R-CDS have red-shift of 7 nm which was due to the increasing of Na element ratio. The onion epidermal cells labeled with R-CDs show that the CDs could pass through the cell wall into the cell and reach the nucleus. The cell wall and the nucleus could be clearly visualized. CDs also shows low toxicity to human bronchial epithelial cells (BEAS-2B) with good biological activity. The obtained results indicate that the CDs and R-CDs have good fluorescent property which could be used as bio-imaging agent.


Assuntos
Fumar Cigarros , Pontos Quânticos , Humanos , Carbono , Boroidretos , Corantes Fluorescentes/química , Íons , Pontos Quânticos/química
12.
Int J Mol Sci ; 23(18)2022 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-36142390

RESUMO

Fructose-1,6-bisphosphate aldolase (EC 4.1.2.13) is a highly conserved enzyme that is involved in glycolysis and gluconeogenesis. In this study, we cloned the fructose-1,6-bisphosphate aldolase gene from Euphausia superba (EsFBA). The full-length cDNA sequence of EsFBA is 1098 bp long and encodes a 365-amino-acid protein. The fructose-1,6-bisphosphate aldolase gene was expressed in Escherichia coli (E. coli). A highly purified protein was obtained using HisTrap HP affinity chromatography and size-exclusion chromatography. The predicted three-dimensional structure of EsFBA showed a 65.66% homology with human aldolase, whereas it had the highest homology (84.38%) with the FBA of Penaeus vannamei. Recombinant EsFBA had the highest activity at 45 °C and pH 7.0 in phosphate buffer. By examining the activity of metal ions and EDTA, we found that the effect of metal ions and EDTA on EsFBA's enzyme activity was not significant, while the presence of borohydride severely reduced the enzymatic activity; thus, EsFBA was confirmed to be a class I aldolase. Furthermore, targeted mutations at positions 34, 147, 188, and 230 confirmed that they are key amino acid residues for EsFBA.


Assuntos
Euphausiacea , Frutose-Bifosfato Aldolase , Aldeído Liases/genética , Aminoácidos/metabolismo , Animais , Boroidretos/metabolismo , Clonagem Molecular , DNA Complementar/metabolismo , Ácido Edético/metabolismo , Escherichia coli/metabolismo , Frutose/metabolismo , Frutose-Bifosfato Aldolase/genética , Frutose-Bifosfato Aldolase/metabolismo , Humanos , Cinética , Fosfatos/metabolismo
13.
Chemphyschem ; 23(22): e202200428, 2022 11 18.
Artigo em Inglês | MEDLINE | ID: mdl-36069265

RESUMO

Alkali metal borohydrides are promising candidates for large-scale hydrogen storage. They react spontaneously with water, generating dihydrogen and metaborate salts. While sodium borohydride is the most studied, potassium has the best chance of commercial application. Here we examine the physical and chemical properties of such self-hydrolysis solutions. We do this by following the hydrogen evolution, the pH changes, and monitoring the reaction intermediates using NMR. Most studies on such systems are done using dilute solutions, but real-life applications require high concentrations. We show that increasing the borohydride concentration radically changes the system's microstructure and rheology. The changes are seen already at concentrations as low as 5 w/w%, and are critical above 10 w/w%. While dilute solutions are Newtonian, concentrated reaction solutions display non-Newtonian behaviour, that we attribute to the formation and (dis)entanglement of metaborate oligomers. The implications of these findings towards using borohydride salts for hydrogen storage are discussed.


Assuntos
Hidrogênio , Sais , Boroidretos , Hidrólise , Potássio
14.
Acta Histochem ; 124(7): 151952, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36099745

RESUMO

Immunohistochemistry (IHC) is a powerful biochemical technique that uses antibodies to specifically label and visualize proteins of interests within biological samples. However, fluid-preserved specimens within natural history collection often use fixatives and protocols that induce high background signal (autofluorescence), which hampers IHC as it produces low signal-to-noise ratio. Here, we explored techniques to reduce autofluorescence using sodium borohydride (SBH), citrate buffer, and their combination on fish tissue preserved with paraformaldehyde, formaldehyde, ethanol, and glutaraldehyde. We found SBH was the most effective quenching technique, and applied this pretreatment to the gill or skin of 10 different archival fishes - including specimens that had been preserved in formaldehyde or ethanol for up to 65 and 37 years, respectively. The enzyme Na+/K+-ATPase (NKA) was successfully immunostained and imaged using confocal fluorescence microscopy, allowing for the identification and characterization of NKA-rich ionocytes essential for fish ionic and acid-base homeostasis. Altogether, our SBH-based method facilitates the use of IHC on archival samples, and unlocks the historical record on fish biological responses to environmental factors (such as climate change) using specimens from natural history collections that were preserved decades to centuries ago.


Assuntos
Formaldeído , Museus , Adenosina Trifosfatases , Animais , Boroidretos , Citratos , Etanol , Peixes , Fixadores , Formaldeído/química , Glutaral
15.
ACS Nano ; 16(9): 15206-15214, 2022 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-36054658

RESUMO

Catalyst activity can depend distinctly on nanoparticle size and shape. Therefore, understanding the structure sensitivity of catalytic reactions is of fundamental and technical importance. Experiments with single-particle resolution, where ensemble-averaging is eliminated, are required to study it. Here, we implement the selective trapping of individual spherical, cubic, and octahedral colloidal Au nanocrystals in 100 parallel nanofluidic channels to determine their activity for fluorescein reduction by sodium borohydride using fluorescence microscopy. As the main result, we identify distinct structure sensitivity of the rate-limiting borohydride oxidation step originating from different edge site abundance on the three particle types, as confirmed by first-principles calculations. This advertises nanofluidic reactors for the study of structure-function correlations in catalysis and identifies nanoparticle shape as a key factor in borohydride-mediated catalytic reactions.


Assuntos
Nanopartículas , Boroidretos , Catálise , Fluoresceínas , Nanopartículas/química , Tamanho da Partícula
16.
Chemosphere ; 307(Pt 1): 135780, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35870608

RESUMO

Thermosetting unsaturated polyester resin (UPR) composites were found widespread industrial applications. However, the numerous stable carbon-carbon bonds in cross-linked networks made them intractable for degradation, causing the large-scale composite wastes. Here a nanoscale Fe0 catalyst in-situ forming strategy was exploited to nondestructively recycle carbon fiber (CF) from UPR composites via Fenton-like reaction. The nano-Fe0 catalyst employed in this strategy activated H2O2 for removing UPR, featuring mild conditions and efficient degradation ability. Aiming at facile growth of the catalyst, a porous UPR was achieved by the hydrolysis of alkalic system. The nanoscale Fe0 catalyst was subsequently formed in-situ on the surface of hydrolyzed resin by borohydride reduction. Benefiting from fast mass transfer, the in-situ grown nano-Fe0 showed more efficient degradation ability than added nano-Fe0 or Fe2+ catalyst during Fenton-like reaction. The experiments indicated that hydrolyzed resin could be degraded more than 90% within 80 min, 80 °C. GC-MS, FT-IR analysis and Density functional theory (DFT) calculation were conducted to explained the fracture processes of carbon skeleton in hydrolyzed resin. Especially, a remarkable recovery process of CF from composites was observed, with a 100 percent elimination of resin. The recycled CF cloth exhibited a 99% strength retention and maintained the textile structure, microtopography, chemical structure, resulting in the nondestructive reclaim of CF. This in-situ formed nanoscale Fe0 catalytic degradation strategy may provide a promising practical application for nondestructively recycle CF from UPR composites.


Assuntos
Peróxido de Hidrogênio , Ferro , Boroidretos , Carbono , Fibra de Carbono , Catálise , Peróxido de Hidrogênio/química , Ferro/química , Poliésteres , Espectroscopia de Infravermelho com Transformada de Fourier
17.
Luminescence ; 37(7): 1200-1207, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35560509

RESUMO

Interactions between bovine γ-globulin (BGG) and borohydride-capped silver nanoparticles (BAgNPs) were studied using dynamic light scattering (DLS) and spectroscopic techniques such as UV-vis spectroscopy, fluorescence, and circular dichroism. The results were compared with earlier reported interactions between γ-globulin and citrate-coated AgNPs (CAgNPs). BAgNPs were synthesized and characterized. Irrespective of the coating on AgNPs, nanoparticles had formed ground-state complexes with the protein. CAgNPs, as well as BAgNPs had caused static quenching of tryptophan (Trp) fluorescence of the protein. The change in the capping agent from citrate to borohydride weakened the binding of nanoparticles with the protein. But the same change in capping agent had increased the fluorescence quenching efficiency of AgNPs. Hydrogen bonding and van der Waals interactions were involved in BGG-BAgNPs complex similar to the CAgNPs complex with γ-globulin. Polarity of the Trp microenvironment in BGG was not altered using BAgNPs as opposed to CAgNPs, as supported using synchronous and three-dimensional fluorescence. Resonance light scattering experiments also suggested nano-bio conjugation. Far-UV and near-UV circular dichroism (CD) spectra respectively pointed towards changes in the secondary and tertiary structure of BGG by BAgNPs, which was not observed for CAgNPs.


Assuntos
Nanopartículas Metálicas , Prata , Animais , Boroidretos , Bovinos , Dicroísmo Circular , Citratos , Nanopartículas Metálicas/química , Prata/química , Espectrometria de Fluorescência/métodos , gama-Globulinas
18.
Molecules ; 27(6)2022 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-35335336

RESUMO

In hydrolysis and electro-oxidation of the borohydride anion BH4-, key reactions in the field of energy, one critical short-living intermediate is BH3OH-. When water was used as both solvent and reactant, only BH3OH- is detected by 11B NMR. By moving away from such conditions and using DMF as solvent and water as reactant in excess, four 11B NMR quartets were observed. These signals were due to BH3-based intermediates as suggested by theoretical calculations; they were DMF·BH3, BH3OH-, and B2H7- (i.e., [H3B-H-BH3]- or [H4B-BH3]-). Our results shed light on the importance of BH3 stemming from BH4- and on its capacity as Lewis acid to interact with Lewis bases such as DMF, OH-, and BH4-. These findings are important for a better understanding at the molecular level of hydrolysis of BH4- and production of impurities in boranes synthesis.


Assuntos
Boranos , Ânions , Boroidretos/química , Hidrólise , Água
19.
Chem Rev ; 122(6): 6040-6116, 2022 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-35099940

RESUMO

The number of rare earth (RE) starting materials used in synthesis is staggering, ranging from simple binary metal-halide salts to borohydrides and "designer reagents" such as alkyl and organoaluminate complexes. This review collates the most important starting materials used in RE synthetic chemistry, including essential information on their preparations and uses in modern synthetic methodologies. The review is divided by starting material category and supporting ligands (i.e., metals as synthetic precursors, halides, borohydrides, nitrogen donors, oxygen donors, triflates, and organometallic reagents), and in each section relevant synthetic methodologies and applications are discussed.


Assuntos
Metais Terras Raras , Boroidretos , Ligantes , Metais , Metais Terras Raras/química
20.
Int J Mol Sci ; 24(1)2022 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-36613588

RESUMO

Hydrides have emerged as strong candidates for energy storage applications and their study has attracted wide interest in both the academic and industry sectors. With clear advantages due to the solid-state storage of hydrogen, hydrides and in particular complex hydrides have the ability to tackle environmental pollution by offering the alternative of a clean energy source: hydrogen. However, several drawbacks have detracted this material from going mainstream, and some of these shortcomings have been addressed by nanostructuring/nanoconfinement strategies. With the enhancement of thermodynamic and/or kinetic behavior, nanosized complex hydrides (borohydrides and alanates) have recently conquered new estate in the hydrogen storage field. The current review aims to present the most recent results, many of which illustrate the feasibility of using complex hydrides for the generation of molecular hydrogen in conditions suitable for vehicular and stationary applications. Nanostructuring strategies, either in the pristine or nanoconfined state, coupled with a proper catalyst and the choice of host material can potentially yield a robust nanocomposite to reliably produce H2 in a reversible manner. The key element to tackle for current and future research efforts remains the reproducible means to store H2, which will build up towards a viable hydrogen economy goal. The most recent trends and future prospects will be presented herein.


Assuntos
Nanocompostos , Boroidretos , Poluição Ambiental , Hidrogênio , Indústrias
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...