Adsorptive separation is very important in industry. Generally, the process uses porous solid materials such as zeolites, activated carbons, or silica gels as adsorbents. With an ever increasing need for a more efficient, energy-saving, and environmentally benign procedure for gas separation, adsorbents with tailored structures and tunable surface properties must be found. Metal–organic frameworks (MOFs), constructed by metal-containing nodes connected by organic bridges, are such a new type of porous materials. They are promising candidates as adsorbents for gas separations due to their large surface areas, adjustable pore sizes and controllable properties, as well as acceptable thermal stability. This critical review starts with a brief introduction to gas separation and purification based on selective adsorption, followed by a review of gas selective adsorption in rigid and flexible MOFs. Based on possible mechanisms, selective adsorptions observed in MOFs are classified, and primary relationships between adsorption properties and framework features are analyzed. As a specific example of tailor-made MOFs, mesh-adjustable molecular sieves are emphasized and the underlying working mechanism elucidated. In addition to the experimental aspect, theoretical investigations from adsorption equilibrium to diffusion dynamics via molecular simulations are also briefly reviewed. Furthermore, gas separations in MOFs, including the molecular sieving effect, kinetic separation, the quantum sieving effect for H2/D2 separation, and MOF-based membranes are also summarized (227 references).

Selective gas adsorption and separation in metal–organic frameworks

1. Introduction 20642. Synthesis of Magnetic Nanoparticles 20662.1. Classical Synthesis by Coprecipitation 20662.2. Reactions in Constrained Environments 20682.3. Hydrothermal and High-TemperatureReactions20692.4. Sol-Gel Reactions 20702.5. Polyol Methods 20712.6. Flow Injection Syntheses 20712.7. Electrochemical Methods 20712.8. Aerosol/Vapor Methods 20712.9. Sonolysis 20723. Stabilization of Magnetic Particles 20723.1. Monomeric Stabilizers 20723.1.1. Carboxylates 20733.1.2. Phosphates 20733.2. Inorganic Materials 20733.2.1. Silica 20733.2.2. Gold 20743.3. Polymer Stabilizers 20743.3.1. Dextran 20743.3.2. Polyethylene Glycol (PEG) 20753.3.3. Polyvinyl Alcohol (PVA) 20753.3.4. Alginate 20753.3.5. Chitosan 20753.3.6. Other Polymers 20753.4. Other Strategies for Stabilization 20764. Methods of Vectorization of the Particles 20765. Structural and Physicochemical Characterization 20785.1. Size, Polydispersity, Shape, and SurfaceCharacterization20795.2. Structure of Ferro- or FerrimagneticNanoparticles20805.2.1. Ferro- and Ferrimagnetic Nanoparticles 20805.3. Use of Nanoparticles as Contrast Agents forMRI20825.3.1. High Anisotropy Model 20845.3.2. Small Crystal and Low Anisotropy EnergyLimit20855.3.3. Practical Interests of Magnetic NuclearRelaxation for the Characterization ofSuperparamagnetic Colloid20855.3.4. Relaxation of Agglomerated Systems 20856. Applications 20866.1. MRI: Cellular Labeling, Molecular Imaging(Inﬂammation, Apoptose, etc.)20866.2.

Magnetic Iron Oxide Nanoparticles: Synthesis, Stabilization, Vectorization, Physicochemical Characterizations, and Biological Applications

Detection of chemical and biological agents plays a fundamental role in biomedical, forensic and environmental sciences1–4 as well as in anti bioterrorism applications.5–7 The development of highly sensitive, cost effective, miniature sensors is therefore in high demand which requires advanced technology coupled with fundamental knowledge in chemistry, biology and material sciences.8–13

In general, sensors feature two functional components: a recognition element to provide selective/specific binding with the target analytes and a transducer component for signaling the binding event. An efficient sensor relies heavily on these two essential components for the recognition process in terms of response time, signal to noise (S/N) ratio, selectivity and limits of detection (LOD).14,15 Therefore, designing sensors with higher efficacy depends on the development of novel materials to improve both the recognition and transduction processes. Nanomaterials feature unique physicochemical properties that can be of great utility in creating new recognition and transduction processes for chemical and biological sensors15–27 as well as improving the S/N ratio by miniaturization of the sensor elements.28

Gold nanoparticles (AuNPs) possess distinct physical and chemical attributes that make them excellent scaffolds for the fabrication of novel chemical and biological sensors (Figure 1).29–36 First, AuNPs can be synthesized in a straightforward manner and can be made highly stable. Second, they possess unique optoelectronic properties. Third, they provide high surface-to-volume ratio with excellent biocompatibility using appropriate ligands.30 Fourth, these properties of AuNPs can be readily tuned varying their size, shape and the surrounding chemical environment. For example, the binding event between recognition element and the analyte can alter physicochemical properties of transducer AuNPs, such as plasmon resonance absorption, conductivity, redox behavior, etc. that in turn can generate a detectable response signal. Finally, AuNPs offer a suitable platform for multi-functionalization with a wide range of organic or biological ligands for the selective binding and detection of small molecules and biological targets.30–32,36 Each of these attributes of AuNPs has allowed researchers to develop novel sensing strategies with improved sensitivity, stability and selectivity. In the last decade of research, the advent of AuNP as a sensory element provided us a broad spectrum of innovative approaches for the detection of metal ions, small molecules, proteins, nucleic acids, malignant cells, etc. in a rapid and efficient manner.37



Figure 1

Physical properties of AuNPs and schematic illustration of an AuNP-based detection system.



In this current review, we have highlighted the several synthetic routes and properties of AuNPs that make them excellent probes for different sensing strategies. Furthermore, we will discuss various sensing strategies and major advances in the last two decades of research utilizing AuNPs in the detection of variety of target analytes including metal ions, organic molecules, proteins, nucleic acids, and microorganisms.

/pdf/gold-nanoparticles-in-chemical-and-biological-sensing-5e2qojkdzn.pdf

Gold nanoparticles in chemical and biological sensing.

Core/Shell Nanoparticles: Classes, Properties, Synthesis Mechanisms, Characterization, and Applications

Lanthanide-based luminescent hybrid materials.

Procede de preparation d'un materiau a base d'un aluminosilicate, ledit aluminosilicate etant constitue d'aluminosilicate de structure hexagonale, caracterise en ce qu'il comprend une seule etape de frittage dans laquelle on realise le frittage d'un melange de poudres de precurseurs dudit aluminosilicate, comprenant une poudre d'hydroxyde d'aluminium Al(OH)3, par une technique de frittage a chaud avec un champ electrique pulse SPS ; moyennant quoi on obtient un materiau a base d'un aluminosilicate, ledit aluminosilicate etant constitue d'aluminosilicate de structure hexagonale. Le materiau a base d'un aluminosilicate prepare par ledit procede peut etre utilise dans un procede pour preparer un materiau composite constitue par une matrice en aluminosilicate renforcee par des renforts en oxyde de metal ou de metalloide.

Procede de preparation d'un materiau a base d'aluminosilicate, et procede de preparation d'un materiau composite a matrice en aluminosilicate

Editorial: Sol-Gel Science at the Frontiers of Innovation

The invention relates to a method for production of thin layer semiconductors, photosensitised by one or more chromophore substances with at least one cycle, comprising the following successive steps: a) a step of deposition on a support of at least one layer of a solution, obtained by sol-gel polymerisation of one or more precursors of semiconductor oxide(s), said semiconductor oxide(s) being selected from metallic oxides and mixtures thereof, b) a drying step for the layer obtained in a), c) an acid, basic or neutral treatment step in a liquid or gaseous medium of the layer obtained in b), d) a photosensitisation step of the layer obtained in c) using one or more chromophore substances, by bringing said layer into contact with a solution comprising the chromophore substance(s). The above is of application in the production of electrodes for photovoltaic cells and electroluminescent diodes.

Method for production of photosensitised thin layer semiconductors

Scandium oxides nanopowders have been synthesized using a sol-gel route. ScOOH nanoparticles have been first prepared in solution using ScCl3, xH2O as precursor. Influence of pH and reflux time on particles size and shape has been studied. Sc2O3 nanoparticles were then obtained after ScOOH sol drying. Sols were characterized by laser granulometry, thermogravimetry and differential analysis (TGA- DSC). Depending on pH, 40 to 1000 nm size ScOOH particles can be obtained. At a given pH, the reflux time duration also influences the ScOOH particles size. The ScOOH sol can be used to prepare highly pure Sc2O3 nanopowders. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microcopy (TEM), were used to characterize Sc203 nanopowders obtained from the various ScOOH solutions. The DSC and laser granulometry data indicate a strong relation between the nanoparticles size and the temperature of transformation of g-ScOOH to Sc2O3. Depending on the sol preparation various particles Sc2O3 size can then be obtained allowing the selection of the more suitable powder for transparent ceramic preparation.

Philippe Belleville

Papers

Procede de preparation d'un materiau a base d'aluminosilicate, et procede de preparation d'un materiau composite a matrice en aluminosilicate

Editorial: Sol-Gel Science at the Frontiers of Innovation

Method for production of photosensitised thin layer semiconductors

Synthesis of Scandium Oxide Nanoparticles from Solution

Method for the preparation of a nanoporous layer of nanoparticles