Recent advances of Rh-based intermetallic nanomaterials for catalytic applications

Rhodium (Rh) has received widespread attention in fundamental catalytic research and numerous industrial catalytic applications. Compared to homogeneous catalysts, Rh-based nanomaterials as heterogeneous catalysts are much easier to separate and collect after usage, making them more suitable for commercial use. To this purpose, there has been a constant demand in constructing stable and highly active Rh-based nanomaterials. In contrast to Rh-based solid solutions with a random distribution of metallic atoms in the lattice, Rh-based intermetallic compounds (IMCs) with a fixed stoichiometric ratio and an ordered atomic arrangement can ensure the homogenous distribution of active sites and structural stability in the catalytic process. In this review, we concentrate on the fabrication of Rh-based IMCs for catalytic applications. Various synthetic methods and protocols for the controlled preparation of Rh-based IMC are illustrated. Meanwhile, the catalytic applications and corresponding catalytic mechanisms are discussed. In addition, personal perspectives about the remaining challenges and prospects in this field are provided. We believe this review will be useful in directing the development of Rh-based IMC catalysts for heterogeneous catalysis.     

Polymeric conjugates for drug delivery

The field of polymer therapeutics has evolved over the past decade and has resulted in the development of polymer-drug conjugates with a wide variety of architectures and chemical properties. Whereas traditional non-degradable polymeric carriers such as poly(ethylene glycol) (PEG) and N-(2-hydroxypropyl methacrylamide) (HPMA) copolymers have been translated to use in the clinic, functionalized polymer-drug conjugates are increasingly being utilized to obtain biodegradable, stimuli-sensitive, and targeted systems in an attempt to further enhance localized drug delivery and ease of elimination. In addition, the study of conjugates bearing both therapeutic and diagnostic agents has resulted in multifunctional carriers with the potential to both "see and treat" patients. In this paper, the rational design of polymer-drug conjugates will be discussed followed by a review of different classes of conjugates currently under investigation. The design and chemistry used for the synthesis of various conjugates will be presented with additional comments on their potential applications and current developmental status.     

Sucrose analogs: an attractive (bio)source for glycodiversification

Covering: up to April 2012Sucrose is a widespread carbohydrate in nature and is involved in many biological processes. Its natural abundance makes it a very appealing renewable raw material for the synthetic production of high-valued molecules. To further diversify the structure and the inherent properties of these molecules, the access to sucrose analogs is of utmost interest and has historically been widely explored through chemical means. Nature also offers a large panel of sucrose-scaffold derivatives, including phosphorylated or highly substituted phenylpropanoid esters amenable to transformation. Additionally, the use of microorganisms or enzymes could provide an alternative ecologically-compatible manner to diversify sucrose-scaffold derivatives to enable the synthesis of oligo- or polysaccharides, glycoconjugates or polymers that could exhibit original properties for biotechnological applications. This review covers the main biological routes to sucrose derivatives or analogs that are prevalent in nature, that can be obtained via enzymatic processes and the potential applications of such sucrose derivatives in sugar bioconversion, in particular through the engineering of substrates, enzymes or microorganisms.     

Covalently cross-linked proteins & polysaccharides: Formation,characterisation and potential applications

This review presents recent research conducted on the development of various protein-polysaccharide conjugates, their functional properties and industrial applications. These conjugates are formed by the glycosylation of food proteins with carbohydrates via the Maillard reaction and are capable of improving the functional properties of proteins. The Maillard reaction facilitates covalent bonding between a reducing group of a carbohydrate and an amino group of a protein under controlled conditions of temperature, time, pH, and relative humidity. There is a great deal of interest in modifying the functional properties of proteins and in the use of novel conjugates for various industrial applications. This review discusses various methods and their implications for preparing and characterising these conjugates. Furthermore, the physicochemical properties of conjugates such as solubility, thermal stability, emulsifying activity, emulsion stabilising properties, gelling and foaming properties are also analysed. A novel processing technology, a spinning disc reactor, could be an alternative process for the production of protein–polysaccharide conjugates, with desirable functionality in different food systems.     

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.     

Advances and trends in the design, analysis, and characterization of polymer–protein conjugates for “PEGylaided” bioprocesses

In addition to their use as therapeutics and because of their enhanced properties, PEGylated proteins have potential application in fields such as bioprocessing. However, the use of PEGylated conjugates to improve the performance of bioprocess has not been widely explored. This limited additional industrial use of PEG-protein conjugates can be attributed to the fact that PEGylation reactions, separation of the products, and final characterization of the structure and activity of the resulting species are not trivial tasks. The development of bioprocessing operations based on PEGylated proteins relies heavily in the use of analytical tools that must sometimes be adapted from the strategies used in pharmaceutical conjugate development. For instance, to evaluate conjugate performance in bioprocessing operations, both chromatographic and non-chromatographic steps must be used to separate and quantify the resulting reaction species. Characterization of the conjugates by mass spectrometry, circular dichroism, and specific activity assays, among other adapted techniques, is then required to evaluate the feasibility of using the conjugates in any operation. Correct selection of the technical and analytical methods in each of the steps from design of the PEGylation reaction to its final engineering application will ensure success in implementing a "PEGylaided" process. In this context, the objective of this review is to describe technological and analytical trends in developing successful applications of PEGylated conjugates in bioprocesses and to describe potential fields in which these proteins can be exploited.     

Silatranes: a review on their synthesis, structure, reactivity and applications

This critical review summarizes progress of the rapidly developing and very active field of silatrane chemistry. The first part of the review deals with general synthetic approaches used to synthesize different silatranes. The most interesting feature of silatranes, i.e., variation of Si-N bond length on the basis of the axial substituent of Si, and other structural features, are described in the second part with special emphasis on crystallographic and theoretical studies. It is followed by a discussion on the reactivity of various silatranes. Silatranes have now gained acceptance for a wide variety of applications which are summarized in the last section of review. Some of them have extensive interest due to their medical use to heal wounds or stimulate hair-growth (pilotropic activity), biological properties, pharmacological properties e.g. antitumor, anticancer, antibacterial, anti-inflammatory, fungicidal activity, stimulating effect in animal production and seed germination effects. The review focuses on the extended potential of silatranes in sol-gel processes, mesoporous zeotypes, atomic force microscopy, commercial products such as adhesion promoters, polymer formation and rubber compositions. This critical review will be helpful for general researchers, experts, advanced undergraduates and newcomers working on silatrane chemistry as this review presents greater emphasis on synthesis and characterization, structural properties, reactivity and applications of silatranes in the field of biology, material science, sol-gel chemistry, pharmaceutics, agriculture and medicine (311 references).     

Beyond nC60: strategies for identification of transformation products of fullerene oxidation in aquatic and biological samples

Owing to their exceptional properties and versatility, fullerenes are in widespread use for numerous applications. Increased production and use of fullerenes will inevitably result in accelerated environmental release. However, study of the occurrence, fate, and transport of fullerenes in the environment is complicated because a variety of surface modifications can occur as a result of either intentional functionalization or natural processes. To gain a better understanding of the effect and risk of fullerenes on environmental health, it is necessary to acquire reliable data on the parent compounds and their congeners. Whereas currently established quantification methods generally focus on analysis of unmodified fullerenes, we discuss in this review the occurrence and analysis of oxidized fullerene congeners (i.e., their corresponding epoxides and polyhydroxylated derivatives) in the environment and in biological specimens. We present possible strategies for detection and quantification of parent nanomaterials and their various derivatives.     

氢氧根和烷氧基负离子含氧亲核试剂在富勒烯衍生化中的应用

富勒烯衍生化合物在有机光电、生物医学等领域表现出良好应用前景,相关的富勒烯衍生化方法研究引起了广泛关注,近年来发展迅速。富勒烯由于具有较强的缺电子性质,容易与亲核试剂反应。但相比于碳亲核试剂,含氧亲核试剂与富勒烯的反应发展缓慢,长期被忽略。我们结合本课题组最近开展的工作,对OH~-与MeO~-含氧亲核试剂参与的富勒烯衍生化反应的最新进展进行了总结,并对反应机理进行了较为详尽的阐述,为进一步扩展富勒烯衍生化方法提供参考。     

Recent advances in biocatalysis by directed enzyme evolution

Naturally occurring enzymes are remarkable biocatalysts with numerous potential applications in industry and medicine. However, many of their catalyst properties often need to be further tailored to meet the specific requirements of a given application. Within this context, directed evolution has emerged over the past decade as a powerful tool for engineering enzymes with new or improved functions. This review summarizes recent advances in applying directed evolution approaches to alter various enzyme properties such as activity, selectivity (enantio- and regio-), substrate specificity, stability, and solubility. Special attention will be paid to the creation of novel enzyme activities and products by directed evolution.     

The use of naphthalene-2,3-dicarboxaldehyde for the analysis of primary amines using high-performance liquid chromatography and capillary electrophoresis

This paper reviews analytical methods, instrumental developments and applications for derivatization of primary amines with naphthalene-2,3-dicarboxaldehyde using fluorescence and chemiluminescence detection with capillary electrophoresis (CE) and high performance liquid chromatography (HPLC). The use of lasers as well as lamps as the excitation source for fluorescence detection is discussed. The detection limit observed with naphthalene-2,3-dicarboxaldehyde derivatization is often lower and better than those obtained with other analytical separations and other fluorescent dyes. In addition, this paper describes the crucial points that influence the stability of NDA primary amine derivatives, and summarize the separation, derivatization and migration conditions of the different techniques, with their advantages and drawbacks.     

In Vitro Production of Plant Peroxidases—A Review

In the latest two decades, the interest received by plant enzymes has increased significantly. Plant enzymes such as peroxidases are widely used in medicine as diagnostic tools and in the bioremediation and biobleaching industries, among others. Traditionally, these enzymes have been obtained from a natural source, a process that is sometimes laborious and affected by weather conditions and low yields. To overcome this hurdle, some efforts have been made to establish plant cell cultures in vitro to use the system as a continuous source of plant enzymes. The focus of this review will be the production of plant peroxidases in vitro, including novel approaches such as the use of bioreactors and genetically transformed tissues to enhance the yield of desired enzymes.     

A review on <Superscript>90</Superscript>Y-labeled compounds and biomolecules

The field of therapeutic nuclear medicine is emerging rapidly as choice of treatment in oncology and other cellular malignancies. The growth of this branch of nuclear medicine is greatly facilitated by the introduction of a number of new radiopharmaceuticals and radionuclides. ⁹⁰Y-radiopharmaceuticals have confirmed their worth in medical and clinical areas in a very short span of time. The ⁹⁰Y is a radioisotope widely used for therapeutic purposes and considerable perfection has been made to understand the chemistry of ⁹⁰Y-labeled radiopharmaceuticals. The development of these radiopharmaceuticals can be made favorable by using appropriate buffer, incubation period, optimal pH, specific activity and reaction temperature. In this review, we have discussed the preparation of range of ⁹⁰Y transporting biological molecules such as antibodies radiolabeled peptides, antigens and microsphere with their clinical applications.     

Kinetic analysis of semisynthetic peroxidase enzymes containing a covalent DNA-heme adduct as the cofactor

The reconstitution of apo enzymes with DNA oligonucleotide-modified heme (protoporphyrin IX) cofactors has been employed as a tool to produce artificial enzymes that can be specifically immobilized at the solid surfaces. To this end, covalent heme-DNA adducts were synthesized and subsequently used in the reconstitution of apo myoglobin (aMb) and apo horseradish peroxidase (aHRP). The reconstitution produced catalytically active enzymes that contained one or two DNA oligomers coupled to the enzyme in the close proximity to the active site. Kinetic studies of these DNA-enzyme conjugates, carried out with two substrates, ABTS and Amplex Red, showed a remarkable increase in peroxidase activity of the DNA-Mb enzymes while a decrease in enzymatic activity was observed for the DNA-HRP enzymes. All DNA-enzyme conjugates were capable of specific binding to a solid support containing complementary DNA oligomers as capture probes. Kinetic analysis of the enzymes immobilized by the DNA-directed immobilization method revealed that the enzymes remained active after hybridization to the capture oligomers. The programmable binding properties enabled by DNA hybridization make such semisynthetic enzyme conjugates useful for a broad range of applications, particularly in biocatalysis, electrochemical sensing, and as building blocks for biomaterials.     

Derivatization trends in capillary electrophoresis

This survey gives an overview of recent derivatization protocols, starting from 1996, in combination with capillary electrophoresis (CE). Derivatization is mainly used for enhancing the detection sensitivity of CE, especially in combination with laser-induced fluorescence. Derivatization procedures are classified in tables in pre-, on- and postcapillary arrangements and, more specifically, arranged into functional groups being derivatized. The amine and reducing ends of saccharides are reported most frequently, but examples are also given for derivatization of thiols, hydroxyl, carboxylic, and carbonyl groups, and inorganic ions. Other reasons for derivatization concern indirect chiral separations, enhancing electrospray characteristics, or incorporation of a suitable charge into the analytes. Special attention is paid to the increasing field of research using on-line precapillary derivatization with CE and microdialysis for in vivo monitoring of neurotransmitter concentrations. The on-capillary derivatization can be divided in several approaches, such as the at-inlet, zone-passing and throughout method. The postcapillary mode is represented by gap designs, and membrane reactors, but especially the combination of separation, derivatization and detection on a chip is a new emerging field of research. This review, which can be seen as a sequel to our earlier reported review covering the years 1991-1995, gives an impression of current derivatization applications and highlights new developments in this field.     

Recent progresses of derivatization approaches in the targeted lipidomics analysis by mass spectrometry

Lipidomics plays an essential role in the development of an improved understanding of lipids metabolism and the identification of new biomarkers or therapeutic targets of related diseases. The strong analytical power of mass spectrometry and its rapid developments in the respect of instruments and techniques have significantly accelerated the emerging lipidomics and related application fields in biology, medicine, and pharmacy. The strategy of chemical derivatization can remarkably improve the shortcomings of mass spectrometric analytical technologies of shotgun lipidomics and liquid chromatography mass spectrometry, and in the past decade many related studies have been reported for fatty acids, glycerophospholipids, sphingomyelins, monoglycerides, diacylglycerols, long‐chain bases, steroids, and so on. Therefore, this review will focus on new chemical derivatization approaches about the research progresses of shotgun‐based and liquid chromatography mass spectrometry–based targeted lipidomics (from 2005 to July 2019, most of reports emerged in the past 5 years), and put forward the problems and prospects in this field. It is expected to be helpful for the design and synthesis of new derivatization reagents, especially the outstanding stable isotope labeling derivatization reagents, and the development and application of new chemical derivatization strategies and matched mass spectrometric analysis methods.     

Antimicrobial Properties of Chitosan and Chitosan Derivatives in the Treatment of Enteric Infections

Antibiotics played an important role in controlling the development of enteric infection. However, the emergence of antibiotic resistance and gut dysbiosis led to a growing interest in the use of natural antimicrobial agents as alternatives for therapy and disinfection. Chitosan is a nontoxic natural antimicrobial polymer and is approved by GRAS (Generally Recognized as Safe by the United States Food and Drug Administration). Chitosan and chitosan derivatives can kill microbes by neutralizing negative charges on the microbial surface. Besides, chemical modifications give chitosan derivatives better water solubility and antimicrobial property. This review gives an overview of the preparation of chitosan, its derivatives, and the conjugates with other polymers and nanoparticles with better antimicrobial properties, explains the direct and indirect mechanisms of action of chitosan, and summarizes current treatment for enteric infections as well as the role of chitosan and chitosan derivatives in the antimicrobial agents in enteric infections. Finally, we suggested future directions for further research to improve the treatment of enteric infections and to develop more useful chitosan derivatives and conjugates.     

Fullerenes for rechargeable battery applications: Recent developments and future perspectives

The development of high-performance batteries is inseparable from the exploration of new materials.Among them,fullerene C60 as an allotrope of carbon has many unique properties that are beneficial for battery applications,including precise structure,controllable derivatization,good solubility,and rich redox chemistry.In this review,we summarize the recent progress of fullerene-based materials in the field of rechargeable batteries and the key issues that need to be solved in the future application of fullerene.We hope this review can provide guidance and stimulate research about the applications of fullerenes in the field of energy storage.     

Enzyme—Albumin polymers

The widespread use of enzymes as drugs or therapeutic agents has been limited by (a) enzyme availability, (b) biodegradation of administered enzyme, (c) immunogenecity of the enzyme as a foreign protein, and (d) accessibility of the enzyme to the appropriate site of action. It has become obvious that due to these limitations, the administration of free or native enzyme is not likely to be effective. Various mechanisms of protecting or packaging enzymes to offset some of these drawbacks have been described. We have been successful in producing conjugates of a number of different enzymes with a molar excess of homologous albumin. The resulting enzyme-albumin complex is resistant to proteolytic and heat inactivation and is apparently non-immunogenic. Using specific ligands crosslinked to the enzyme-albumin conjugate we have been able to target these conjugates to specific receptor sites and specific tissues. Ligands including cell surface-recognizing antibodies and hormones such as insulin have been used. These approaches offer new possibilities for the increased use of enzymes in medicine.