Injectable Thermogelling Nanostructured Ink as Simultaneous Optical and Magnetic Resonance Imaging Contrast Agent for Image-Guided Surgery.

The development of efficient and biocompatible contrast agents is particularly urgent for modern clinical surgery. Nanostructured materials raised great interest as contrast agents for different imaging techniques, for which essential features are high contrasts, and in the case of precise clinical surgery, minimization of the signal spatial dispersion when embedded in biological tissues. This study deals with the development of a multimodal contrast agent based on an injectable hydrogel nanocomposite containing a lanthanide-activated layered double hydroxide coupled to a biocompatible dye (indocyanine green), emitting in the first biological window.

Fabrication of Europium-Doped CaF Films via Sol-Gel Synthesis as Down-Shifting Layers for Solar Cell Applications.

In the present work, an in-depth study on the sol-gel process for the fabrication of Eu-doped CaF materials in the form of thin films has been addressed for the production of down-shifting layers. Fine-tuning of the operative parameters, such as the annealing temperature, substrate nature and doping ion percentage, has been finalized in order to obtain Eu(III)-doped CaF thin films via a reproducible and selective solution process for down-shifting applications. An accurate balance of such parameters allows for obtaining films with high uniformity in terms of both their structural and compositional features.

Chirality in luminescent CsCuBr microcrystals produced ligand-assisted reprecipitation.

Herein we report new chiral luminescent CsCuBr needle-like microcrystals and the analysis of their optical properties and the effect of the ligand structure on the transfer of chirality.

From Nanothermometry to Bioimaging: Lanthanide-Activated KYF Nanostructures as Biocompatible Multifunctional Tools for Nanomedicine.

Lanthanide-activated fluoride-based nanostructures are extremely interesting multifunctional tools for many modern applications in nanomedicine, e.g., bioimaging, sensing, drug delivery, and photodynamic therapy.

Doped Ferrite Nanoparticles Exhibiting Self-Regulating Temperature as Magnetic Fluid Hyperthermia Antitumoral Agents, with Diagnostic Capability in Magnetic Resonance Imaging and Magnetic Particle Imaging.

This paper reports a comprehensive investigation of a magnetic nanoparticle (MNP), named M55, which belongs to a class of innovative doped ferrite nanomaterials, characterized by a self-limiting temperature. M55 is obtained from M48, an MNP previously described by our group, by implementing an additional purification step in the synthesis. M55, after citrate and glucose coating, is named G-M55.

Chiral non-stoichiometric ternary silver indium sulfide quantum dots: investigation on the chirality transfer by cysteine.

Chiral semiconductor quantum dots have recently received broad attention due to their promising application in several fields such as sensing and photonics. The extensive work in the last few years was focused on the observation of the chiroptical properties in binary Cd based systems. Herein, we report on the first evidence of ligand-induced chirality in silver indium sulfide semiconductor quantum dots.

Synthesis, characterization and photocatalytic properties of nanostructured lanthanide doped β-NaYF/TiO composite films.

The photocatalytic approach is known to be one of the most promising advanced oxidation processes for the tertiary treatment of polluted water. In this paper, β-NaYF/TiO composite films have been synthetized through a novel sol-gel/spin-coating approach using a mixture of β-diketonate complexes of Na and Y, and Yb, Tm, Gd, Eu as doping ions, together with the TiO P25 nanoparticles. The herein pioneering approach represents an easy, straightforward and industrially appealing method for the fabrication of doped β-NaYF/TiO composites.

Cubic hexagonal - phase, size and morphology effects on the photoluminescence quantum yield of NaGdF:Er/Yb upconverting nanoparticles.

Upconverting nanoparticles (UCNPs) are well-known for their capacity to convert near-infrared light into UV/visible light, benefitting various applications where light triggering is required. At the nanoscale, loss of luminescence intensity is observed and thus, a decrease in photoluminescence quantum yield (PLQY), usually ascribed to surface quenching. We evaluate this by measuring the PLQY of NaGdF:Er,Yb UCNPs as a function of size ( 15 to 100 nm) and shape (spheres, cubes, hexagons).

The formation mechanism and chirality evolution of chiral carbon dots prepared radical assisted synthesis at room temperature.

We report on a Cu(ii) catalyzed process for the production of cysteine based chiral carbon dots; the process does not require any thermal treatment and the carbon dot formation is driven by the production of reactive radical species that are generated in the reaction media by the catalytic role played by the multivalent transition metal. The nanomaterial presents a well-defined chirality and the enantioselectivity of the synthesis is proved by the isolation of both the carbon dot enantiomers. We focused our attention on the processes that take place during the carbon dot formation and the relationship with the structure of the organic starting material.

Nanoparticles exhibiting self-regulating temperature as innovative agents for Magnetic Fluid Hyperthermia.

During the last few years, for therapeutic purposes in oncology, considerable attention has been focused on a method called magnetic fluid hyperthermia (MFH) based on local heating of tumor cells. In this paper, an innovative, promising nanomaterial, M48 composed of iron oxide-based phases has been tested. M48 shows self-regulating temperature due to the observable second order magnetic phase transition from ferromagnetic to paramagnetic state.

Sodium niobate based hierarchical 3D perovskite nanoparticle clusters.

We report a microwave assisted synthesis of NaNbO3 perovskite mesocrystals with a hierarchical morphology formed by the self-assembly of nanoparticles in particle clusters. The synthesis method combines non-aqueous sol-gel synthesis and microwave heating in a single step process that allows us to isolate crystalline single phase NaNbO3 in few minutes. A detailed investigation of the effect of the reaction temperature on the crystallinity and morphology of the product was conducted.

Microfluidic Crystallization of Surfactant-Free Doped Zinc Sulfide Nanoparticles for Optical Bioimaging Applications.

The room-temperature controlled crystallization of monodispersed ZnS nanoparticles (average size of 5 nm) doped with luminescent ions (such as Mn, Eu, Sm, Nd, and Yb) was achieved via a microfluidic approach. The preparation did not require any stabilizing ligands or surfactants, minimizing potential sources of impurities. The synthesized nanomaterials were characterized from a structural (XRD and XAS at lanthanide L edges), morphological (TEM), and compositional (XPS, ICP-MS) perspective, giving complementary information on the materials' features.

Exploring the Phase-Selective, Green, Hydrothermal Synthesis of Upconverting Doped Sodium Yttrium Fluoride: Effects of Temperature, Time, and Precursors.

The aim of this work was i) to develop a hydrothermal, low-temperature synthesis protocol affording the upconverting hexagonal phase NaYF with suitable dopants while adhering to the "green chemistry" standards and ii) to explore the effect that different parameters have on the products. In optimizing the synthesis protocol, short reaction times and low temperatures (below 150 °C) were considered. Yb and Er ions were chosen as dopants for the NaYF material.

Physical-Chemical Properties of Biogenic Selenium Nanostructures Produced by SeITE02 and sp. MPV1.

SeITE02 and sp. MPV1 were isolated from the rhizosphere soil of the selenium-hyperaccumulator legume and waste material from a dumping site for roasted pyrites, respectively. Here, these bacterial strains were studied as cell factories to generate selenium-nanostructures (SeNS) under metabolically controlled growth conditions.

Reliability of rare-earth-doped infrared luminescent nanothermometers.

The use of infrared-emitting rare-earth-doped luminescent nanoparticles as nanothermometers has attracted great attention during the last few years. The scientific community has identified rare-earth-doped luminescent nanoparticles as one of the most sensitive and versatile systems for contactless local temperature sensing in a great variety of fields, but especially in nanomedicine. Researchers are nowadays focused on the design and development of multifunctional nanothermometers with new spectral operation ranges, outstanding brightness, and enhanced sensitivities.

Engineering efficient upconverting nanothermometers using Eu ions.

Upconversion nanothermometry combines the possibility of optically sensing temperatures in very small areas, such as microfluidic channels or on microelectronic chips, with a simple detection setup in the visible spectral range and reduced heat transfer after near-infrared (NIR) excitation. We propose a ratiometric strategy based on Eu ion luminescence activated through upconversion processes. Yb ions act as a sensitizer in the NIR region (980 nm), and energy is transferred to Tm ions that in turn excite Eu ions whose luminescence is shown to be thermally sensitive.

Novel sol-gel fabrication of Yb/Tm co-doped β-NaYF thin films and investigation of their upconversion properties.

An innovative sol-gel process, using a mixture of Na(hfa)·tetraglyme and RE(hfa)3·diglyme (RE = Y, Yb, Tm) complexes, has been optimized to produce upconverting β-NaYF4:Yb3+/Tm3+ thin films. The X-ray diffraction (XRD) analysis confirms that the new sol-gel preparation route yields reproducibly and selectively the hexagonal Na(Y1.5Na0.

Luminescent and paramagnetic properties of nanoparticles shed light on their interactions with proteins.

Nanoparticles have been recognized as promising tools for targeted drug-delivery and protein therapeutics. However, the mechanisms of protein-nanoparticle interaction and the dynamics underlying the binding process are poorly understood. Here, we present a general methodology for the characterization of protein-nanoparticle interaction on a molecular level.

Citrate-stabilized lanthanide-doped nanoparticles: brain penetration and interaction with immune cells and neurons.

Aim: To unravel key aspects of the use of lanthanide-doped nanoparticles (NPs) in biomedicine, the interaction with immune and brain cells.

Materials & Methods: Effects of citrate-stabilized CaF and SrF: Yb, Er NPs (13-15 nm) on human dendritic cells and neurons were assessed in vitro. In vivo distribution was analyzed in mice at tissue and ultrastructural levels, and with glia immunophenotyping.

Paramagnetic Nanoparticles Leave Their Mark on Nuclear Spins of Transiently Adsorbed Proteins.

The successful application of nanomaterials in biosciences necessitates an in-depth understanding of how they interface with biomolecules. Transient associations of proteins with nanoparticles (NPs) are accessible by solution NMR spectroscopy, albeit with some limitations. The incorporation of paramagnetic centers into NPs offers new opportunities to explore bio-nano interfaces.

Enhancing optical forces on fluorescent up-converting nanoparticles by surface charge tailoring.

3D remote control of multifunctional fluorescent up-converting nanoparticles (UCNPs) using optical forces is being required for a great variety of applications including single-particle spectroscopy, single-particle intracellular sensing, controlled and selective light-activated drug delivery and light control at the nanoscale. Most of these potential applications find a serious limitation in the reduced value of optical forces (tens of fN) acting on these nanoparticles, due to their reduced dimensions (typically around 10 nm). In this work, this limitation is faced and it is demonstrated that the magnitude of optical forces acting on UCNPs can be enhanced by more than one order of magnitude by a controlled modification of the particle/medium interface.

Simple, common but functional: biocompatible and luminescent rare-earth doped magnesium and calcium hydroxides from miniemulsion.

Nanostructured (d∼ 20-35 nm) and highly luminescent Ca(OH):Ln and Mg(OH):Ln (Ln = Eu, Sm, Tb, Mg(Ca)/Ln = 20 : 1 atomic) nanostructures were obtained in inverse (water in oil - w/o) miniemulsion (ME), by exploiting the nanosized compartments of the droplets to spatially confine the hydroxide precipitation in basic environment (NaOH). The functional nanostructures were prepared using different surfactants (Span80 (span) and a mixture of Igepal co-630 and Brij 52 (mix)) to optimise ME stability and hydroxide biocompatibility as well as tune the droplet sizes. X-Ray diffraction (XRD) analyses testify the achievement of a pure brucite-Mg(OH)-phase and pure portlandite-Ca(OH)-phase with a high degree of crystallinity.

Multifunctional nanoprobes based on upconverting lanthanide doped CaF: towards biocompatible materials for biomedical imaging.

Water dispersible Gd,Yb,Er and Gd,Yb,Tm doped CaF nanoparticles (NPs) were prepared by one-pot hydrothermal synthesis using citrate ions as capping agents without the need for any post-synthesis reaction. UC emissions are easily observed in the visible and infrared regions upon NIR diode laser excitation at 980 nm. EPR spectroscopy confirms the substitutional nature of the rare-earth doping, while magnetometric studies reveal that the NPs have a useful magnetization.

PEG-capped, lanthanide doped GdF3 nanoparticles: luminescent and T2 contrast agents for optical and MRI multimodal imaging.

A facile method for the synthesis of water dispersible Er(3+)/Yb(3+) and Tm(3+)/Yb(3+) doped upconverting GdF(3) nanoparticles is reported. Strong upconversion emissions are observed in the red (for Er/Yb doped) and near-infrared (for Tm/Yb doped) regions upon laser excitation at 980 nm. The PEG coating ensures a good dispersion of the system in water and reduces the radiationless de-excitation of the excited states of the Er(3+) and Tm(3+) ions by water molecules.

NIR-to-NIR two-photon excited CaF2:Tm3+,Yb3+ nanoparticles: multifunctional nanoprobes for highly penetrating fluorescence bio-imaging.

In this study, we report on the remarkable two-photon excited fluorescence efficiency in the "biological window" of CaF(2):Tm(3+),Yb(3+) nanoparticles. On the basis of the strong Tm(3+) ion emission (at around 800 nm), tissue penetration depths as large as 2 mm have been demonstrated, which are more than 4 times those achievable based on the visible emissions in comparable CaF(2):Er(3+),Yb(3+) nanoparticles. The outstanding penetration depth, together with the fluorescence thermal sensitivity demonstrated here, makes CaF(2):Tm(3+),Yb(3+) nanoparticles ideal candidates as multifunctional nanoprobes for high contrast and highly penetrating in vivo fluorescence imaging applications.