Javier Fernández-Lodeiro

Corrole and corrole functionalized silica nanoparticles as new metal ion chemosensors: a case of silver satellite nanoparticles formation.

Corrole macrocycles are very appealing dyes for incorporation into light harvesting devices. This work shows the sensorial ability of 5,10,15-tris(pentafluorophenyl)corrole 1 and its monoanionic species toward Na(+), Ca(2+), Cu(2+), Cd(2+), Pb(2+), Hg(2+), Ag(+), and Al(3+) metal ions in toluene and acetonitrile. The photophysical studies toward metal ions were carried out by absorption and emission spectroscopy. From all metal ions studied, corrole 1 shows to be colorimetric for Hg(2+) allowing a naked-eye detection of Hg(2+) through a change of color from purple to blue in acetonitrile and from green to yellow in toluene. In addition a new β-imine corrole 4 was successful synthesized and further functionalized with 3-isocyanatopropyl-trimethoxysilane resulting in an alkoxysilane derivative 5. The grafting of alkoxysilane derivative 5 with optically transparent silica nanoparticles (SiNPs) was achieved succesfully. The new-coated silica nanoparticles with corrole 5 were studied in the presence of Cu(2+), Hg(2+), and Ag(+) as metal ion probes. Interestingly, upon addition of Ag(+), groups of satellite AgNPs were formed around the SiNPs and were checked by transmission electron microscopy (TEM). At same time, a change of color from green to yellow was observed.

Steady-State and Time-Resolved Investigations on Pyrene-Based Chemosensors

Two novel fluorescent probes bearing a single (P) and two (a podand-like structure, L) pyrene units derived from 1,5-bis(2-aminophenoxy)-3-oxopentane have been synthesized and investigated in dioxane using UV-vis absorption, and steady-state and time-resolved (in a picosecond time scale) emission spectroscopy; in the gas phase, matrix-assisted laser desorption ionization mass spectrometry was employed. In dioxane, the absorption and emission spectra of P present a unique band with maxima at 361 and 392 nm, which have been associated with the monomer absorption and emission bands, respectively. In dioxane, for compound L, an additional band with a maximum at ∼525 nm is observed; upon the addition of water, an emissive band (with maxima varying from 405 to 490 nm) appears in both P and L spectra; this is discussed in terms of the emission of a species with charge character. Upon metal addition (Cu(2+), Zn(2+), and Ag(+)) to P, a gradual quenching effect of the monomer emission is observed and found to be more pronounced with Cu(2+). In the case of L, upon the addition of metal cations, the long emission band (∼550 nm) decreases and the monomer emission band increases (with an isoemissive point at ∼450 nm) and no evidence for the intermediate band (at ∼405-490 nm) now exists. Time-resolved data in dioxane/water mixtures showed that for P and L these two fit double- and triple-exponential decay laws, respectively. With P, this has been attributed to a two-state system, which involves the monomer and a charged species, with its emission maxima varying with the polarity of the media (here mirrored by its dielectric constant), which can potentially be addressed to an exciplex-like species, whereas with L, it has been attributed to a three-state system involving, in addition to these two species, an excimer. From absorption and fluorescence excitation and time-resolved data, evidence is given for the presence of intramolecular dimer formation in the ground state.

Novel nanocomposites based on a strawberry-like gold- coated magnetite (Fe@Au) for protein separation in multiple myeloma serum samples

A new process to produce magnetite partially coated with strawberry-like gold nanoparticles in aqueous media is reported. The fast response to magnetic fields and optical properties of gold nanoparticle-based colloidal systems are the two main advantages of this new Fe@Au nanomaterial. These advantages allow for the use of this new colloidal nanomaterial for various purposes in proteomics and biomedicine, as proteins can bind to the surface, and the surface can also be functionalized. As proof-of-concept, the new Fe@Au nanoparticles have been assessed in biomarker discovery as a tool for pre-concentration and separation of proteins from complex proteomes. To this end, sera from healthy people were compared with sera from patients diagnosed with multiple myeloma. The application of this new Fe@Au nanomaterial combined with mass spectrometry has allowed for the identification of 53 proteins, and it has also shown that the heat shock protein HSP75 and the plasma protease C1 inhibitor are potential biomarkers for diagnostics and control of multiple myeloma progression.

Polyamine Ligand-Mediated Self-Assembly of Gold and Silver Nanoparticles into Chainlike Structures in Aqueous Solution: Towards New Nanostructured Chemosensors

Polyamine ligands are very versatile compounds due to their water solubility and flexibility. In the present work, we have exploited the binding ability of a polyamine molecular linker (L2−) bearing different functional groups, which favors the self-assembling of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) into 1D nanochains in aqueous solution. The chainlike assemblies of AuNPs and AgNPs were structurally stable for a long period of time, during which their characteristic optical properties remained unchanged. The mechanism of AuNPs and AgNPs chain assembly associated with the induction of electric dipole–dipole interactions arising from the partial ligand exchange of surface-adsorbed citrate ions by (L2−) was investigated. UV/Vis spectrophotometry and transmission electron microscopy (TEM) were used to determine timedependent structural changes associated with formation of the 1D nanoparticle structures. Finally, the sensing of Hg2+ in aqueous solution using AgNPs@(L)2− and AuNPs@(L)2− assemblies was also carried out in aqueous solution.

New-coated fluorescent silver nanoparticles with a fluorescein thiol esther derivative: fluorescent enhancement upon interaction with heavy metal ions

Abstract A new fluorescein thiol esther derivative L was successfully synthesized and fully characterized. The interaction of compound L with spherical silver nanoparticles (AgNPs) was explored in toluene, through the exchange of the tetraoctylammonium bromated (TOAB) molecules stabilizing the silver nanoparticle surface (AgNPs@TOAB). A new hybrid system AgNPs@L was obtained in which an intense metal-enhancement fluorescence phenomenon takes place. The behaviour of the new-coated AgNPs@L system was explored in the presence of silent toxic metal ions, such as Hg2+, Pb2+ and Tl+ in organic phase. Surprisingly, system AgNPs@L reveals to be sensitive to Hg2+ ions over the other heavy metal ions studied.

1D chain fluorescein-functionalized gold and silver nanoparticles as new optical mercury chemosensor in aqueous media

A colorimetric system using noble metal nanoparticles (NPs), for the detection of small concentrations of mercury ion (Hg2+) in water is described. Fluorescein-functionalized Au and Ag NPs were self-assembled into networks of one-dimensional chains in the presence of mercury(II) by chelation process; this causes an easily optical measurable change in the absorption spectrum of the particles in aqueous solution.

Supercritical CO2-Assisted Spray Drying of Strawberry-Like Gold-Coated Magnetite Nanocomposites in Chitosan Powders for Inhalation

Lung cancer is one of the leading causes of death worldwide. Therefore, it is of extreme importance to develop new systems that can deliver anticancer drugs into the site of action when initiating a treatment. Recently, the use of nanotechnology and particle engineering has enabled the development of new drug delivery platforms for pulmonary delivery. In this work, POXylated strawberry-like gold-coated magnetite nanocomposites and ibuprofen (IBP) were encapsulated into a chitosan matrix using Supercritical Assisted Spray Drying (SASD). The dry powder formulations showed adequate morphology and aerodynamic performances (fine particle fraction 48%–55% and aerodynamic diameter of 2.6–2.8 µm) for deep lung deposition through the pulmonary route. Moreover, the release kinetics of IBP was also investigated showing a faster release of the drug at pH 6.8, the pH of lung cancer. POXylated strawberry-like gold-coated magnetite nanocomposites proved to have suitable sizes for cellular internalization and their fluorescent capabilities enable their future use in in vitro cell based assays. As a proof-of-concept, the reported results show that these nano-in-micro formulations could be potential drug vehicles for pulmonary administration.

Green and Red Fluorescent Dyes for Translational Applications in Imaging and Sensing Analytes: A Dual-Color Flag

Abstract Invited for this months cover picture is the BIOSCOPE group of Professors Carlos Lodeiro and José Luis Capelo at the REQUIMTE/UCIBIO‐LAQv‐FCT University NOVA of Lisbon (Portugal), and their collaborators. The cover picture is devoted to Translational Research, and shows the Portuguese Flag represented by the interaction between cells and Janus gold/silver nanoparticles functionalized with rhodamine (red) and Fluorescein (green) dyes as tools for biomedical translational research. Read the full text of their Review at 10.1002/open.201700135.

New Synthesis of Gold‐ and Silver‐Based Nano‐Tetracycline Composites

Abstract A new synthetic methodology of water‐soluble gold and silver nanoparticles (AuNPs@TC and AgNPs@TC), using the antibiotic tetracycline (TC) as co‐reducing and stabilizing agent, is reported. Both colloids exhibit high water stability. The average sizes obtained were 25±10 and 15±5 nm, respectively. Both composites were tested against TC‐resistant bacteria, presenting an increasing antibacterial effect in the case of AgNPs@TC. The sensing towards metal ions was also explored. An interesting and reversible affinity of AuNPs@TC towards AlIII cations in an aqueous system was also observed.

Unraveling the organotellurium chemistry applied to the synthesis of gold nanomaterials

Long-term preservation of the properties of gold nanoparticles in both solution and the dry powder form can be difficult. We have overcome this challenge by using organotellurium derivatives as both reducing agents and stabilizers in the synthesis of gold nanoparticles. This new synthetic protocol takes advantage of the photochemical and oxidative properties of diphenyl ditelluride (Ph2Te2), which, so far, have never been exploited in the synthesis of gold nanoparticles. The Au/Te core/shell (inorganic/organic) hybrid nanomaterial can be obtained in a one-step reaction, using only Ph2Te2 and HAuCl4. By modifying the reaction conditions, different resonance conditions of the gold core are achieved due to the formation of external shells with different thicknesses. The organotellurium shell can be easily removed by resuspension of the nanoparticles in environmentally friendly solvents, such as water or ethanol, making the Au core available for subsequent applications. A mechanism for the formation of core/shell nanoparticles has also been discussed.