Inorganic ion-exchangers: Their role in chromatographic radionuclide generators for the decade 1993–2002

Ion-exchangers are found not only in water purification processes, the original major application, but also in analytical chemistry for the separation and isolation of elements, hydrometallurgy, inorganic chemistry and biochemistry, in food technology, and of course in many specialized fields related to the utilization of atomic energy. The use of organic ion-exchangers is limited by virtue of their limited stability under harsh conditions, whereas inorganic ion-exchangers possess important properties, which make them very useful for chemical separation and purification in intense radiation fields. The availability of short-lived radionuclides from radionuclide generators provides an inexpensive and convenient alternative to in-house radioisotope production facilities such as accelerators and cyclotrons. Due to their simplicity of operation, chromatographic based generators have been the method of choice, although generators based on solvent extraction and on volatization and sublimation have also been developed, and are routinely used. In this paper use of inorganic ion-exchangers for the development of radionuclide generators for the decade 1993–2002 has been compiled.     

Nanomaterial-based adsorbents: the prospect of developing new generation radionuclide generators to meet future research and clinical demands

Nanostructured materials by virtue of huge surface to volume ratios, altered physical properties, tailored surface chemistry, favorable adsorption characteristics, and enhanced surface reactivity resulting from the nanoscale dimensions, have attracted considerable attention as a new class of adsorbent material in column chromatographic separation. This emerging class of adsorbent represents an innovative paradigm and is expected to play an important role in the development of radionuclide generators for nuclear medicine. The optimal combination of suitable nanomaterial and appropriate parent/daughter radionuclide pair forms the basis of such generators. Development of such generators is currently under intensive investigations and the utility of such systems is expected to pave the way for broad panoply of diagnostic and therapeutic applications in nuclear medicine. While nanomaterial-based radionuclide generator is still in its infancy, the use of such novel class of adsorbents is expected to have potential impact on shaping the radionuclide generator technology of future generation. This review provides a comprehensive summary on the utility of nanomaterials as effective adsorbents in the development column chromatographic radionuclide generators for medical applications. This overview outlines a critical assessment of role of the nanosorbents, recent developments, the contemporary status, and key challenges and apertures to the near future.     

Analytical methods for separating and isolating magnetic nanoparticles

Despite the large body of literature describing the synthesis of magnetic nanoparticles, few analytical tools are commonly used for their purification and analysis. Due to their unique physical and chemical properties, magnetic nanoparticles are appealing candidates for biomedical applications and analytical separations. Yet in the absence of methods for assessing and assuring their purity, the ultimate use of magnetic particles and heterostructures is likely to be limited. In this review, we summarize the separation techniques that have been initially used for this purpose. For magnetic nanoparticles, it is the use of an applied magnetic flux or field gradient that enables separations. Flow based techniques are combined with applied magnetic fields to give methods such as magnetic field flow fractionation and high gradient magnetic separation. Additional techniques have been explored for manipulating particles in microfluidic channels and in mesoporous membranes. Further development of these and new analytical tools for separation and analysis of colloidal particles is critically important to enable the practical use of these, particularly for medicinal purposes.     

Cellular and foamed plastics as separation media A new geometrical form of the solid phase in analytical liquid-solid contact

There has been considerable interest during the last few years in using cellular (foamed) plastics (mainly polyurethanes) either unloaded or as a means of immobilizing hydrophobic organic reagents, powdered ion-exchangers or finely divided precipitates, for the collection and separation of inorganic or organic species from aqueous solution. Foamed plastics with anchored (bonded) functional groups have also been used for the same purpose. It has been realized that the application of cellular plastics is often advantageous not only for quantitative work but also for qualitative and semiquantitative analysis. Methods available on the application of cellular and foamed plastics for the collection, separation and recovery of various inorganic and organic components from aqueous solution are reviewed.     

137Cs sorption on granular inorganic ion-exchangers based on titanium and zirconium hydroxophosphates

We have studied the sorption properties of some granular inorganic ion-exchangers synthesized by gel technology, such as titanium and zirconium hydroxophosphates (THP, ZHP), titanium and zirconium molybdophosphates and titanium and zirconium phosphate-ferrocyanides. A high selectivity of THP and ZHP modified with ferrocyanide and molybdate ions to¹³⁷Cs has been found. The possibility of applying inorganic sorbents for the purification of cesium-137 contaminated foodstuff is illustrated on the examples of fish treatment.     

Austauscher mit cyclischen Polyethern als Ankergruppen—II: Anwendungen

Exchangers with cyclic polyethers as anchor groups have a large range of applications such as separations of cations with a common anion, of anions with a common cation, and of neutral organic compounds, and the determination of water by elution chromatography. Some crown ether monomers, especially 4- and 4,4′-alkyl-substituted benzo-derivatives are suitable for extractions and their adducts with heteropoly acids are used as liquid ion-exchangers. The exchangers are also applied in thin-layer chromatography and thin-layer electrophoresis. Furthermore the exchangers are successfully used in preparative chemistry, e.g., in salt conversions in order to isolate salts which are difficult to prepare by other means, in isolation and purification of organic compounds, and for anion activation in organic reactions.     

基于点击化学的色谱分离材料研究新进展

自诺贝尔奖获得者Sharpless教授2001年首次提出点击化学概念以来,该类反应凭借条件温和、反应迅速、产量高、副产物少、分离提纯简单等优势,迅速拓展至材料和生命等诸多科学领域,成为一种强大的模块化合成工具。目前,点击化学反应已成为设计制备分离材料的重要手段,展现出蓬勃发展的现状。本文首先简要地回顾了点击化学的发展历程并介绍了其独特优势,然后聚焦于柱色谱和膜色谱两大分离领域,系统地综述了近5年发表的基于点击化学的色谱分离材料相关报道,重点归纳了叠氮-炔、巯基-烯和巯基-炔这3种常见点击反应类型在色谱分离材料研究中的最新进展,最后对点击化学在开发高效分离材料方面的发展前景进行了展望。     

Sustainability of microporous polymers and their applications

Microporous polymers (MPs) are studied for their intriguing chemistry and physics as well as their potential application in catalytic transformations, gas-separation processes, water purification and so on. Here, we critically review MPs with respect to the sustainability aspects of their synthesis as well as their applications that have sustainable character. Some MPs have been synthesized from monomers derived from biomass resources, but there is certainly a large potential for further developments. There are also opportunities to improve the sustainability of MP synthesis in terms of the use of solvents, catalysts, and related aspects. The applications of MPs in processes related to sustainability depend upon multiple properties. A rich and flexible chemistry is important to applications as catalysts for, among other useful reactions, the photoreduction of CO₂ and selective oxidation. The (ultra)micropore volume of MPs are crucial in gas-separation applications such as CO₂ capture, and the chemisorption of CO₂ on MP-tethered alkylamines could offer a means to remove that gas from dilute mixtures. When it comes to the storage of H₂ and CH₄ in MPs for onboard use in fuel cell or biogas cars, volumetric capacity is paramount, meaning that the density of the MPs must be considered. Finally, for use in separation and purifications from liquid mixtures (aqueous or hydrocarbon-based), crosslinked MPs are more limited than the solution-processable MPs that can be more easily processed into films and membranes.     

金属有机框架材料的研究进展

金属有机框架(metal-organic frameworks,MOFs)材料是一类由有机配体与金属中心经过自组装形成的具有可调节孔径的材料。与传统无机多孔材料相比,MOFs材料具有更大的比表面积,更高的孔隙率,结构及功能更加多样,因而已经被广泛应用于气体吸附与分离、传感器、药物缓释、催化反应等领域中。新兴材料的出现极大地促进了各个学科间的相互发展,本文综述了近年来MOFs材料的研究发展,包括MOFs材料自身的特点、国内外发展现状、应用领域以及复合MOFs材料的研究热点,并对今后的发展进行了展望。     

Modern separation techniques for the efficient workup in organic synthesis

The shift of paradigm in combinatorial chemistry, from large compound libraries (of mixtures) on a small scale towards defined compound libraries where each compound is prepared in an individual well, has stimulated the search for alternative separation approaches. The key to a rapid and efficient synthesis is not only the parallel arrangement of reactions, but simple work-up procedures so as to circumvent time-consuming and laborious purification steps. During the initial development stages of combinatorial synthesis it was believed that rational synthesis of individual compounds could only be achieved by solid-phase strategies. However, there are a number of problems in solid-phase chemistry: most notably there is the need for a suitable linker unit, the limitation of the reaction conditions to certain solvents and reagents, and the heterogeneous reaction conditions. Further disadvantages are: the moderate loading capacities of the polymeric support and the limited stability of the solid support. In the last few years several new separation techniques have been developed. Depending on the chemical problem or the class of compounds to be prepared, one can choose from a whole array of different approaches. Most of these modern separation approaches rely on solution-phase chemistry, even though some of them use solid-phase resins as tools (for example, as scavengers). Several of these separation techniques are based on liquid-liquid phase separation, including ionic liquids, fluorous phases, and supercritical solvents. Besides being benign with respect to their environmental aspects, they also show a number of advantages with respect to the work-up procedures of organic reactions as well as simplicity in the isolation of products. Another set of separation strategies involves polymeric supports (for example, as scavengers or for cyclative cleavage), either as solid phases or as soluble polymeric supports. In contrast to solid-phase resins, soluble polymeric supports allow reactions to be performed under homogeneous conditions, which can be an important factor in catalysis. At the same time, a whole set of techniques has been developed for the separation of these soluble polymeric supports from small target molecules. Finally, miscellaneous separation techniques, such as phase-switchable tags for precipitation by chemical modification or magnetic beads, can accelerate the separation of compounds in a parallel format.     

Metallic radionuclides in the development of diagnostic and therapeutic radiopharmaceuticals

Metallic radionuclides are the mainstay of both diagnostic and therapeutic radiopharmaceuticals. Therapeutic nuclear medicine is less advanced but has tremendous potential if the radionuclide is accurately targeted. Great interest exists in the field of inorganic chemistry for developing target specific radiopharmaceuticals based on radiometals for non-invasive disease detection and cancer radiotherapy. This perspective will focus on the nuclear properties of a few important radiometals and their recent applications to developing radiopharmaceuticals for imaging and therapy. Other topics for discussion will include imaging techniques, radiotherapy, analytical techniques, and radiation safety. The ultimate goal of this perspective is to introduce inorganic chemists to the field of nuclear medicine and radiopharmaceutical development, where many applications of fundamental inorganic chemistry can be found.     

Polymer Composites for Thermoelectric Applications

This review covers recently reported polymer composites that show a thermoelectric (TE) effect and thus have potential application as thermoelectric generators and Peltier coolers. The growing need for CO₂‐minimizing energy sources and thermal management systems makes the development of new TE materials a key challenge for researchers across many fields, particularly in light of the scarcity or toxicity of traditional inorganic TE materials based on Te and Pb. Recent reports of composites with inorganic and organic additives in conjugated and insulating polymer matrices are covered, as well as the techniques needed to fully characterize their TE properties.     

Composite sorbents of inorganic ion-exchangers and polyacrylonitrile binding matrix

Methods of preparation of granules of inorganic ion exchangers as well as methods for improvement of granular strength of these materials are reviewed. The resulting ion exchangers are classified in three groups—“intrinsic”, supported and composite ion exchangers. Their properties are compared and possibilities of their technological application are evaluated. A new method of preparation of inorganic-organic composite sorbents of inorganic ion-exchangers and polyacrylonitrile binding matrix is described, advantages and disadvantages of such sorbents are discussed. Proposed fields of application include tratment of liquid radioactive and/or hazardous wastes, decontamination of natural water as well as analytical applications.     

离子液体与生物大分子相互作用研究进展

离子液体作为一类新型绿色溶剂,因其独特的理化性质,被广泛应用于催化、有机合成、分离富集和电化学等领域。其中,离子液体在生物大分子的分离纯化、催化和降解方面显示出良好的应用前景,成为研究的热点领域之一。本文从离子液体与生物大分子的本质关系出发,对离子液体在DNA和蛋白质的分离纯化、酶的活性稳定性和天然纤维素溶解等过程中与生物大分子之间的相互作用进行了综述。     

Re-emergence of the important role of radionuclide generators to provide diagnostic and therapeutic radionuclides to meet future research and clinical demands

Radionuclide generators have been the main stay of diagnostic nuclear medicine and it is no exaggeration to state that the growth of nuclear medicine would not have happened to the present levels but for the availability of ⁹⁹Mo/^99mTc generator. This article provides a brief account of the various radionuclide generators currently in clinical use or which have made substantial progress or likely to be materialized in the foreseeable future to bring evolutional progress in nuclear medicine. Further, a brief outline on the regulatory challenges and impact on radionuclide generator technology with the emergence of professionally run central radiopharmacies have been provided.     

Microfluidics in Inorganic Chemistry

The application of microfluidics in chemistry has gained significant importance in the recent years. Miniaturized chemistry platforms provide controlled fluid transport, rapid chemical reactions, and cost‐saving advantages over conventional reactors. The advantages of microfluidics have been clearly established in the field of analytical and bioanalytical sciences and in the field of organic synthesis. It is less true in the field of inorganic chemistry and materials science; however in inorganic chemistry it has mostly been used for the separation and selective extraction of metal ions. Microfluidics has been used in materials science mainly for the improvement of nanoparticle synthesis, namely metal, metal oxide, and semiconductor nanoparticles. Microfluidic devices can also be used for the formulation of more advanced and sophisticated inorganic materials or hybrids.     

Expanding the utility of proteins as platforms for coordination chemistry

Whether for constructing advanced materials and complex biological devices or for building sophisticated coordination complexes with diverse metal-based functions, proteins are nature's favorite building blocks. Yet, our ability to control the assembly of proteins or to use them as ligand platforms for inorganic chemistry has been somewhat limited. In this review, we highlight our work from the past four years, which has aimed to exploit the utility of a protein scaffold in both regards. First, by considering proteins as “simple” ligand platforms and controlling the metal coordination chemistry on their surfaces, we show how their self-assembly can be readily dictated by metal binding. Second, we show how metal-mediated protein self-assembly leads to novel metal centers buried within protein interfaces. While on one hand our studies have pointed out the challenges of using proteins as ligands, they have also revealed how the extensive, chemically-rich protein surfaces can be exploited to form a network of covalent and non-covalent interactions around interfacial metal centers, providing a powerful handle to control their coordination chemistry.     

铌多酸三维框架材料的研究进展

铌多酸三维框架材料是近年来无机合成化学与材料化学领域的研究热点. 该类材料不但可以将铌多酸的优异特性与框架结构的优点复合起来, 而且在光催化、 主客体化学、 能源转化等领域具有重要的应用前景. 本文总结了近10年来铌多酸三维框架材料的研究进展, 包括了该类材料的合成策略、 结构调控、 性质及应用探索. 此外, 还对当前该类材料的发展所面临的挑战进行了总结, 并对其发展前景进行了展望.     

Separation of metal ions on tin(iv) tungstate and selenite papers

Papers impregnated with the inorganic ion-exchangers tin(IV) tungstate and selenite have been shown to be useful for ion-exchange chromatography of several metal ion mixtures, and suitable solvent systems have been developed and evaluated.     

Protein A chromatography: Challenges and progress in the purification of monoclonal antibodies

Antibodies for therapeutic use are being continuously approved and their demand has been steadily growing. As known, the golden standard for monoclonal antibody (mAb) purification is Protein A affinity chromatography, a technology that has gained high interest because of its great performance and capabilities. The main concerns are the elevated resins costs and their limited lifetime compared to other resins (e.g. ion exchange chromatography). Great efforts have been carried out to improve purification conditions, such as resin characterization and designing alkali/acid stable resins with a longer lifetime. Modification of Protein A ligands and alternative formats such as monoliths membranes and microshperes have been tested to increase the purification performance. New technology has been proposed to improve the large‐scale separation; in addition, alternative ligands have been suggested to capture mAbs instead of Protein A ligand; however, most of the information is locked by pharmaceutical companies. This mini review summarizes and describes the advances, results, and impact on the Protein A chromatography purification processing.