RESUMEN
BACKGROUND: Rare-earth sulfide nanoparticles (NPs) could harness the optical and magnetic features of rare-earth ions for applications in nanotechnology. However, reports of their synthesis are scarce and typically require high temperatures and long synthesis times. RESULTS: Here we present a biosynthesis of terbium sulfide (TbS) NPs using microorganisms, identifying conditions that allow Escherichia coli to extracellularly produce TbS NPs in aqueous media at 37 °C by controlling cellular sulfur metabolism to produce a high concentration of sulfide ions. Electron microscopy revealed ultrasmall spherical NPs with a mean diameter of 4.1 ± 1.3 nm. Electron diffraction indicated a high degree of crystallinity, while elemental mapping confirmed colocalization of terbium and sulfur. The NPs exhibit characteristic absorbance and luminescence of terbium, with downshifting quantum yield (QY) reaching 28.3% and an emission lifetime of ~ 2 ms. CONCLUSIONS: This high QY and long emission lifetime is unusual in a neat rare-earth compound; it is typically associated with rare-earth ions doped into another crystalline lattice to avoid non-radiative cross relaxation. This suggests a reduced role of nonradiative processes in these terbium-based NPs. This is, to our knowledge, the first report revealing the advantage of biosynthesis over chemical synthesis for Rare Earth Element (REE) based NPs, opening routes to new REE-based nanocrystals.
Asunto(s)
Escherichia coli , Metales de Tierras Raras , Sulfuros , Terbio , Terbio/química , Terbio/metabolismo , Escherichia coli/metabolismo , Sulfuros/metabolismo , Sulfuros/química , Metales de Tierras Raras/metabolismo , Metales de Tierras Raras/química , Nanopartículas/química , Luminiscencia , Tecnología Química Verde/métodosRESUMEN
Photodynamic therapy (PDT) applications are limited by the low penetration of UV-visible light into biological tissues. Considering X-rays as an alternative to excite photosensitizers (PS) in a deeper tumor, an intermediate particle able to convert the X-ray energy into visible light (scintillating nanoparticle, ScNP) is necessary. Moreover, accumulation of PS in the target cells is also required. Genetically encoded proteins could be used as a photosensitizer, allowing the exclusive expression of PS inside the tumor cells. Here, the interaction of eGFP, KillerOrange, and KillerRed proteins with LaF3:Tb3+ ScNP was investigated, for the first time, in terms of its physicochemical and energy transfer properties. The protein structure, stability, and function were evaluated upon adverse physiological conditions and X-ray irradiation. Optimal parameters for energy transfer from ScNP to the proteins were investigated, paving the way for the use of genetically encoded photosensitizers for applications in X-ray activated photodynamic therapy.
Asunto(s)
Fluoruros/química , Lantano/química , Proteínas Luminiscentes/química , Nanopartículas/química , Fármacos Fotosensibilizantes/química , Terbio/química , Línea Celular Tumoral , Transferencia de Energía , Humanos , Proteínas Luminiscentes/genética , Modelos Moleculares , Nanopartículas/ultraestructura , Neoplasias/tratamiento farmacológico , Fotoquimioterapia , Fármacos Fotosensibilizantes/metabolismo , Rayos XRESUMEN
An adsorbent-heater-thermometer nanomaterial, (ZIF-8,EuxTby)@AuNP, based on ZIF-8 (adsorbent), containing Eu3+ and/or Tb3+ ions (thermometer) and gold nanoparticles (AuNPs, heater) was designed, synthetized, characterized, and applied to controlled drug release. These composite materials were characterized as core-shell nanocrystals with the AuNPs being the core, around which the crystalline ZIF-8 has grown (shell) and onto which the lanthanide ions have been incorporated or chemosorbed. This shell of ZIF-8 acts as adsorbent of the drugs, the AuNPs act as heaters, while the luminescence intensities of the ligand and the lanthanide ions are used for temperature monitoring. This thermo-responsive material can be activated by visible irradiation to release small molecules in a controlled manner as established for the model pharmaceutical compounds 5-fluorouracil and caffeine. Computer simulations and transition state theory calculations shown that the diffusion of small molecules between neighboring pores in ZIF-8 is severely restricted and involves high-energy barriers. These findings imply that these molecules are uploaded onto and released from the ZIF-8 surface instead of being inside the cavities. This is the first report of ZIF-8 nanocrystals (adsorbents) containing simultaneously lanthanide ions as sensitive nanothermometers and AuNPs as heaters for controlled drug release in a physiological temperature range. These results provide a proof-of-concept that can be applied to other classes of materials, and offer a novel perspective on the design of self-assembly multifunctional thermo-responsive adsorbing materials that are easily prepared and promptly controllable.
Asunto(s)
Preparaciones de Acción Retardada/farmacología , Liberación de Fármacos , Oro/química , Nanopartículas del Metal/química , Nanoestructuras/química , Termómetros , Zeolitas/química , Adsorción , Cafeína/farmacología , Muerte Celular/efectos de los fármacos , Difusión , Erbio/química , Fluorouracilo/farmacología , Luminiscencia , Temperatura , Terbio/química , Factores de TiempoRESUMEN
A new composite was synthesized by the hydrothermal method using a 3D coordination network [Ln2(C4H4O4)3(H2O)2]·H2O (Ln = Eu and Tb) and activated carbon. The coordination network is formed within the pores of the charcoal, allowing for the use of this material as a detoxifying agent.
Asunto(s)
Aldicarb/administración & dosificación , Inhibidores de la Colinesterasa/administración & dosificación , Complejos de Coordinación/administración & dosificación , Europio/administración & dosificación , Terbio/administración & dosificación , Adsorción , Aldicarb/química , Animales , Carbono/química , Carbón Orgánico/administración & dosificación , Carbón Orgánico/química , Inhibidores de la Colinesterasa/química , Complejos de Coordinación/química , Europio/química , Tracto Gastrointestinal/efectos de los fármacos , Tracto Gastrointestinal/patología , Mucosa Intestinal/efectos de los fármacos , Mucosa Intestinal/patología , Ratones , Microvellosidades/efectos de los fármacos , Microvellosidades/patología , Porosidad , Ratas , Terbio/químicaRESUMEN
A innovative 5-Cl-8-oxyquinolinepropoxycalix[4]arene ligand (2) have been prepared, exhibiting, at room temperature, blue fluorescent light emission and resulting in shift band to green fluorescent light (fluorescence mode) in the presence of coordinated Eu(III) and Tb(III) ions. Terbium complex presented phosphorescence emission as noted by typical bands at 490 nm, 545 nm and 585 nm. TG/DTG data exhibited typical thermal behavior for these compounds, however DSC curves showed the melting temperature near 300 °C for the samples, demonstrating an unusual thermal stability when quinoline derivatives are attached to calix[4]arene matrix. This fact strongly suggests an effective approach to preparing the photoluminescent compound associating high chemical and thermal stability.
Asunto(s)
Calixarenos/química , Cloroquinolinoles/química , Luminiscencia , Temperatura , Acetonitrilos/química , Rastreo Diferencial de Calorimetría , Europio/química , Ligandos , Espectroscopía de Resonancia Magnética , Espectrometría de Fluorescencia , Espectrofotometría Infrarroja , Espectrofotometría Ultravioleta , Terbio/química , TermogravimetríaRESUMEN
The synthesis and structures of two new isostructural mononuclear [Ln(L)(NO(3))(H(2)O)(3)](NO(3))(2) complexes, with Ln = Tb (complex 1) and Eu (complex 2), which display high activity in the hydrolysis of the substrate 2,4-bis(dinitrophenyl)phosphate, are reported. These complexes displayed catalytic behavior similar to the mononuclear gadolinium complex [Gd(L)(NO(3))(H(2)O)(3)](NO(3))(2) previously reported by us (Inorg. Chem. 2008, 47, 2919-2921); one hydrolysis reaction in two stages where the diesterase and monoesterase activities could be monitored separately, with the first stage dependent on and the second independent of the complex concentration. Through potentiometric studies, electrospray ionization mass spectrometry (ESI-MS) analysis, and determination of the kinetic behaviors of 1 and 2 in acetonitrile/water solution, the species present in solution could be identified and suggested a dinuclear species, with one hydroxo group, as the most prominent catalyst under mild conditions. The complexes show high activity (k(1) = 7 and 18 s(-1) for 1 and 2, respectively) and catalytic efficiency. Complexes 1 and 2 were found to be active toward the cleavage of plasmid DNA, and complete kinetic studies were carried out. Studies with a radical scavenger (dimethylsulfoxide) confirmed the hydrolytic action of 1 and 2 in the cleavage of DNA. Studies on the incubation of distamycin with plasmid DNA suggested that 1 and 2 are regio-specific, interacting with the minor groove of DNA. These complexes displayed luminescent properties. Complex 1 showed higher emission intensity than 2 due to a more efficient energy transfer between triplet and emission levels of terbium (T --> (5)D(4)), along with nonradiative deactivation mechanisms of the excited states of europium via multiphonon decays and the ligand-to-metal charge transfer state. Lifetime measurements of the (5)D(4) and (5)D(0) excited levels for 1 and 2, respectively, indicated the numbers of coordinated water molecules for the complexes.