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    Wyświetlanie 1-11 z 11
    Tytuł:
    Otrzymywanie nanocząstek substancji bioaktywnych metodą sonochemiczną w kierunku ich osadzania na powierzchniach biomateriałów polimerowych
    Sonochemical synthesis of bioactive nanoparticles towards direct embedding into polymeric biomaterials surfaces
    Autorzy:
    Chytrosz, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/171774.pdf
    Data publikacji:
    2018
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    ultradźwięki
    sonochemia
    kawitacja akustyczna
    nanocząstki
    bioaktywne nanocząstki
    ultrasounds
    sonochemistry
    acoustic cavitation
    nanoparticles
    bioactive nanoparticels
    Opis:
    Nanomaterials are the latest group of materials which owes its special features thanks to their nanosize. The most characteristic properties include the large surface area, strong chemical reactivity and tendency to agglomerate. Nanomaterials have wide applications in several disciplines, i.e. materials engineering, medicine and food technology. These materials have high potential in biomedical engineering thanks to increased biological activity when compared with the bulk material. Recent advances in nanotechnology are currently mostly focused on improvement of effective synthesis methods. Sonochemical irradiation is an effective technique for the synthesis nanoparticles. This method is widely used for inorganic nanoparticles production in contrast to organic ones, which could open powerful possibilities of creating bioactive, therapeutic or self-cleaning surfaces. In principle, the introduction of a strong acoustic field into an aqueous solution induces acoustic cavitation. The nucleation, growth and collapse of the bubble during acoustic cavitation are graphically shown in Figure 1. When the bubble reaches a certain size it become resonant with ultrasonic radiation and rapidly increase in size. Then, the bubble becomes unstable and violently collapses. The collapse of microbubbles produces extremely high localized pressures and temperatures (hundreds bar and thousands K) which lead to hot spot. Conditions of sonochemistry are rather radical in comparison to other chemical processes. Moreover, the synthesis and simultaneously embedding nanoparticles into polymer surfaces are possible. This paper constitutes a review of the recent literature in sonochemical synthesis of organic, bioactive nanoparticles. The introduction will focus on a short overview of sonochemistry, the next part will present the mechanism of formation nanoparticles using ultrasounds. Also, some advantages of sonochemistry as a tool for nanomaterials fabrication is presented. In the next section some examples of bioactive nanoparticles prepared in sonochemical reaction are listed and advantages of sonochemical synthesis are discussed.
    Źródło:
    Wiadomości Chemiczne; 2018, 72, 5-6; 313-325
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Współczesne podejścia elektrochemiczne do oznaczania arsenu
    Recent approaches to electrochemical determination of arsenic
    Autorzy:
    Ozimek, W.
    Rutkowska, I. A.
    Cox, J. A.
    Kulesza, P. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/172485.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    arsen
    oznaczenia elektrochemiczne
    woltamperometria strippingowa
    elektrokataliza
    elektrody modyfikowane
    nanocząstki metali
    nanocząstki tlenków metali
    arsenic
    electrochemical determinations
    stripping voltammetry
    electrocatalysis
    modified electrodes
    metal nanoparticles
    metal oxide nanoparticles
    Opis:
    There has been growing interest in development of new methods for the determination of arsenic due to its high toxity and increasing population in the environment. At present, chromatographic (separation) and spectroscopic (detection) approaches are the most common. Although, they are characterized by high sensitivity and low detection limits, the experimental procedures often require generation of toxic AsH3. Electrochemical methods for the determination of arsenic can be considered as complimentary because they are fairly simple and they are subject to different selectivity criteria. In this respect, various stripping voltammetric procedures are becoming popular. The actual stripping voltammetric measurement consists of two steps in which preconcentration of an analyte at the electrode surface is followed by the so called „stripping” step involving electrode reaction recorded in a form of the voltammetric peak. A representative approach involves reduction of the analyte anions upon application of the sufficiently negative potential to form As(0) on the electrode (e.g. gold) surface; this step is followed by voltammetric oxidation (anodic stripping) of the deposit (to As(III)). In a case of so called cathodic stripping voltammetry, the stationary Hanging Mercury Drop Electrode (HMDE) is often used. During the preconcentration step, an insoluble salt is produced on the electrode surface. To facilitate its formation, copper or selenium species are used as mediators. Under such conditions, insoluble Cu3As2 is generated together with copper amalgam on the surface of HMDE. Because sensitivity and detection limit in electroanalytical determinations strongly depend on the current densities measured, there is a need to search for specific catalytic materials that would induce otherwise highly slow and irreversible redox processes of As(III) (oxidation) and, in particular, As(V) (reduction). Designing effective electrocatalytic materials would be of importance to the development of more sensitive stripping methods and monitoring of arsenic under chromatographic and flow conditions. Representative examples of catalytic systems are provided and discussed here. Some attention is also paid to application of enzymes to sensing of arsenic. Electrochemical determination of arsenic(III) is generally better described in literature. Direct determination of As(V) typically requires its binding into chemical compounds. It is reasonable to expect intense research in future aiming at the developing of new electroanalytical methods for direct selective determination of As(V).
    Źródło:
    Wiadomości Chemiczne; 2015, 69, 9-10; 809-822
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nowe rozwiązania i modyfikacje najpopularniejszych polimerowych nośników substancji aktywnych
    New solutions and modifications of the most popular polymeric carriers of active substances
    Autorzy:
    Odrobińska, Justyna
    Neugebauer, Dorota
    Powiązania:
    https://bibliotekanauki.pl/articles/171574.pdf
    Data publikacji:
    2019
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    koniugaty
    micele
    liposomy
    nanocząstki
    nośniki polimerowe
    conjugates
    micelles
    liposomes
    nanoparticles
    polymeric carriers
    Opis:
    The progress of medicine and cosmetology corresponds to the increase in the need for new drug design and delivery methods, due to the already common cancer risk, as well as other diseases, which are still difficult for curing. Regardless of the type of active substance and its final application, the selection and synthesis of the appropriate carrier is crucial to provide the pharmaceutics to the target with the controlled release for a set period of time, including the intelligent activity. Depending on the way the bioactive substance is bound to carriers in the drug delivery systems (DDS) they are classified onto: carriers that physically encapsulate them inside i.e. liposomes, solid lipid nanoparticles, nanostructural lipid carriers, nanoparticles (nanocapsules, nanospheres), micelles, and carriers that chemically bind the active substance, i.e. conjugates, polyplexes. The current studies are emphasized to achieve the most perfect improvement, which concerns the efficiency of encapsulation, the ability to deliver several compounds simultaneously or sequentially, the productive release, the elimination of side products, the replacement of synthetic polymers by natural, biodegradable, biocompatible and non-toxic polymers. These carriers are also developed in terms of sensitivity to stimuli (one or several simultaneously or sequentially activated) and adapted for combined therapy. Although the subject of active substance delivery with the use of carriers is already widely studied, these are still a needs for the designing of new or the enhancement of the already known DDS. Working on this issue there is hope that today still incurable diseases, neoplastic diseases, as well as the diagnosis of these diseases themselves, will be possible to control and treat in the future. This report presents the current state of the knowledge in the area of DDS, focusing on newly developed solutions in the last years.
    Źródło:
    Wiadomości Chemiczne; 2019, 73, 9-10; 481-501
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nanocząstki tlenku tytanu(IV) : zastosowanie w produktach użytkowych, badania właściwości i oznaczanie techniką spektrometrii mas z plazmą indukcyjnie sprzężoną pracującą w trybie pojedynczej cząstki
    Titanium dioxide nanoparticles : application in consumer products, study of properties and determination by single particle inductively coupled plasma – mass spectrometry
    Autorzy:
    Gruszka, Jakub
    Malejko, Julita
    Godlewska-Żyłkiewicz, Beata
    Powiązania:
    https://bibliotekanauki.pl/articles/172064.pdf
    Data publikacji:
    2019
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    nanocząstki tlenku tytanu(IV)
    rozdzielanie
    techniki łączone
    titanium dioxide nanoparticles
    separation
    hyphenated techniques
    Opis:
    The rapid growth in the production and use of nanomaterials is observed in recent years. Nanoparticles of titanium dioxide (TiO2NPs) are one of the most frequently used nanomaterials. Sunscreens, food additives, food contact materials and textiles are the major fields of current application of TiO2NPs. Due to increasing use of nanomaterials in daily life and thus increasing exposure to them, concerns have been raised about their safety. Likely routes of human exposure to released TiO2NPs as well as their health and environmental effects are presented in this paper. At present, our knowledge about the risk of nanomaterials is incomplete. However, it is known that toxicity of nanoparticles depends on their size, shape, crystal structure, surface morphology, surface area, charge, concentration and solubility (the possibility of dissolution into ionic forms). Therefore, it is necessary to use several complementary analytical techniques to fully characterize the NPs. Common approaches used for the characterization of nanomaterials include microscopy based techniques e.g. transmission electron microscopy (TEM), X-ray techniques e.g. X-ray diffraction (XRD), methods based on optical properties e.g. dynamic light scattering (DLS). Separation of nanoparticulate and ionic forms of metal can be accomplished using chromatographic techniques (such as high performance liquid chromatography (HPLC), size exclusion chromatography (SEC), hydrodynamic chromatography (HDC)) or capillary electrophoresis (CE). Size-resolved NPs and dissolved (ionic) fractions can be further characterized by on-line detectors, such as ICP MS. Recently, single particle inductively coupled plasma mass spectrometry (sp ICP MS) has been gaining increasing attention as a technique for detection, characterization, and quantification of nanoparticles. This technique provides information on individual particles, including particle size, number size distribution, particle number concentration and mass concentration. In addition, sp ICP MS can distinguish dissolved and nanoparticulate forms of an element. The fundamentals, advantages and limitations of this technique, as well as its application for the characterization and quantification of TiO2NPs in different matrices (consumer products, food and environmental samples) are reviewed in this paper.
    Źródło:
    Wiadomości Chemiczne; 2019, 73, 5-6; 367-400
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nanosrebro : zastosowanie, migracja i metody oznaczania
    Nanosilver : uses, migration and methods of determination
    Autorzy:
    Malejko, J.
    Godlewska-Żyłkiewicz, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/171890.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    nanocząstki srebra
    migracja
    biodostępność
    rozdzielanie
    techniki łączone
    silver nanoparticles
    migration
    bioavailability
    separation
    hyphenated techniques
    Opis:
    The rapid growth in the commercial application of silver nanoparticles (AgNPs) will certainly increase the exposure to these metals among humans and in the environment. Nano-size silver particles have a broad spectrum of antimicrobial activity and therefore are incorporated into various materials, including medical textiles, which claim to prevent infection, as well as more common textiles, like anti-odour sportswear, underwear, socks and gloves. On the market there is also a variety of home consumer products claiming to contain nanosilver, for example disinfecting sprays (to disinfect hard surfaces, towels, sheets, and clothing), kitchen cutting boards, washing machines, refrigerators, dishwashers, pillows and mattresses, toothbrushes, toilet seats, water filters, and cosmetics. Nanosilver is added to food contact materials to preserve the packaged food for a particularly long period of time by inhibiting the growth of microbes. There is a number of in vitro studies showing cytotoxic effects and genotoxic DNA damaging capacity of AgNPs to a variety of mammalian cell types [24]. However, there are only a few in vivo studies on their genotoxicity. Likely routes of human exposure to released nanoparticles include inhalation, ingestion and dermal penetration. Evaluation of the health impact of AgNPs requires information on how readily and in what forms this substance can be released from the material. At present, the availability of such data is limited (Tab. 1). Size of metal-based nanoparticles is an important factor determining their physical and chemical properties as well as their bioavailability and toxicity. The methods used for the size characterisation of AgNPs in different matrices (consumer products, biological and environmental samples) (Tab. 2), as well as for speciation analysis of various forms of silver, namely AgNPs and silver ions, are reviewed in this paper. Off-line methods such as centrifugal ultrafiltration, (ultra)centrifugation, dialysis, and cloud point extraction are used in order to distinguish between nanoparticles and dissolved forms of silver. Field-flow fractionation (FFF) in different modes is used for nanoparticle size dependent separation [50]. Size-resolved AgNPs fractions are further characterised by on-line detectors, such as UV-Vis, ICP OES or ICP MS. ICP MS in single-particle detection mode is used for simultaneous determination of nanosilver and silver ions [38]. The application of capillary electrophoresis [40] and liquid chromatography [41, 42] for the separation of nano and ionic forms of silver is also discussed in this work.
    Źródło:
    Wiadomości Chemiczne; 2015, 69, 9-10; 847-867
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nieorganiczne nanocząstki w medycynie nuklearnej
    Inorganic nanoparticles in nuclear medicine
    Autorzy:
    Kasperek, A.
    Bilewicz, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/172564.pdf
    Data publikacji:
    2012
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    nanocząstki
    medycyna nuklearna
    system transportu leków
    nośniki leków
    nanoparticles
    nuclear medicine
    drug delivery systems
    drug carriers
    Opis:
    Rapid and widespread growth in the use of nuclear medicine for both diagnosis and therapy of disease has been the driving force for a design of novel radiopharmaceuticals. Particularly, recent progress in nanotechnology gives the possibility of designing new carriers for delivering radionuclides in a manner to overcome some limitation such as nonspecific biodistribution and targeting, water insolubility, poor oral bioavailability and others. There are several perspective therapeutic and diagnostic radionuclides which cannot be bound to biomolecule via chemical bonds. Nanocarriers gives the opportunity for binding such radionuclides. Nanoparticles have to be designed with an optimal size (above 100 nm) and surface characteristic to easily penetrate the barriers in the body and prevent elimination by reticuloendothelial system. Among nanoparticles which are used for delivery and targeting are polymers, lipids, viruses, organometallic compounds, precious metals or metal oxides. This article presents a brief review of the applications, advantages, difficulties and future perspective of inorganic nanoparticles, which can be used as radionuclide delivery systems. The main direction of developing new nanostructures for nuclear medicine is to create multimodal agents which are suitable for such combined methods as PET /MRI or PET /NIRF. Also combination of diagnostic and therapeutic agents in one nanocontainer is possible.
    Źródło:
    Wiadomości Chemiczne; 2012, 66, 7-8; 697-714
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Biologiczna synteza nanocząstek metali
    Biological synthesis of metal nanoparticles
    Autorzy:
    Maliszewska, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/171642.pdf
    Data publikacji:
    2012
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    nanocząstki metali
    kropki kwantowe
    biosynteza
    bakterie
    drożdże
    grzyby
    rośliny
    metal nanoparticles
    quantum dots
    biosynthesis
    bacteria
    yeasts
    fungi
    plants
    Opis:
    Nanotechnology has attracted a great interest in recent years due to its expected impact on many areas such as energy, medicine, electronics and space industries. One of the most important aspects in researching nanotechnology is a synthesis of metal nanoparticles of well-defined sizes, shapes and controlled monodispersity. One of the exciting methods is the production of metal nanostructures using biological systems such as microbes, yeast, fungi and several plant extracts. Biological systems provide many examples of specifically modified nanostructured molecules. Perhaps, the best known are the magnetotactic bacteria which intracellularly synthesize magnetic nanocrystals in magnetosomes. The production of many other metal and metal alloy nanoparticles by organisms is a consequence of detoxification pathways. Organisms have evolved specific mechanisms to prevent excessive accumulation of metals. There are two probable ways to capture or trap the metal ions, electrostatic interaction and/or secretion of substances that will adhere the ions. For the process of intracellular synthesis of nanoparticles, the ions are involved in a nutrient exchange and/or substance diffusion. Thereafter, the functional reducing agents (i.e. reducing sugars, fatty acids, glutathione, flavonoids, terpenoids, fitochelatines etc.) and/or enzymes (NAD+/NADP+- dependent reductases, hydrogenases, oxidases), convert the harmful ions into non-harmful matters. Finally, the nuclei grow and subsequently intracellularly or extracellularly accumulate to form nanoparticles. Despite numerous research made in this area, the mechanism of biosynthesis is not a fully understood. In this paper an overview of the use of living organisms in the biosynthesis of metal nanoparticles is given and different mechanisms leading to the formation of nanoparticles are demonstrated.
    Źródło:
    Wiadomości Chemiczne; 2012, 66, 11-12; 1023-1040
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nanomateriały w spektrometrii mas z laserową desorpcją/jonizacją wspomaganą powierzchnią
    Nanomaterials applied in surface-assisted laser desorption/ionization mass spectrometry
    Autorzy:
    Arendowski, Adrian
    Powiązania:
    https://bibliotekanauki.pl/articles/2200434.pdf
    Data publikacji:
    2022
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    laserowa desorpcja/jonizacja
    metody bezmatrycowe
    nanocząstki
    SALDI
    spektrometria mas
    laser desorption/ionization
    mass spectrometry
    matrix-free methods
    nanoparticles
    Opis:
    Laser desorption/ionization (LDI) is one of the most popular ionization techniques currently used in mass spectrometry (MS). This technique is most commonly used in a variant of matrix-assisted laser desorption/ionization (MALDI), which uses low molecular weight organic acid mixed with the sample to support the ionization process. However, this approach has some shortcomings such as: high chemical background in the spectral region below m/z 700 making it difficult to analyze compounds giving signals in this spectral region, inhomogeneous co-crystallization of analyte and matrix leading to the formation of so-called "sweet spots", i.e. inhomogeneous distribution of analyte in the crystallizing matrix. For these reasons, increasing research attention is focused on the possibilities offered by the use of matrix-free systems based on nanostructures in laser methods, which are referred to as surface-assisted laser desorption/ionization (SALDI). The use of nanostructures in LDI MS has made it possible to analyze low molecular compounds, often at very low concentrations, without the presence of matrix-derived chemical background, contributing to more applications of the LDI MS method. This work describes what the SALDI technique is and reviews the nanomaterials used in different variations of the approach. Among the described materials used in SALDI there are nanomaterials based on carbon and silicon, including the DIOS method, as well as techniques based on nanoparticles of gold, silver, platinum and titanium oxide. For each method, application examples are given for the detection of different classes of chemical compounds, often also in complex biological mixtures.
    Źródło:
    Wiadomości Chemiczne; 2022, 76, 9-10; 735--754
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fotochemiczna synteza nanocząstek srebra i złota
    Photochemical synthesis of silver and gold nanoparticles
    Autorzy:
    Krajczewski, J.
    Kudelski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/172175.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    rezonans plazmonowy
    synteza nanomateriałów
    anizotropowe nanocząstki metali
    nanorezonatory elektromagnetyczne
    plasmon resonance
    plasmon-driven synthesis of nanomaterials
    anisotropic metal nanoclusters
    light concentration at the nanometer scale
    Opis:
    The activity in nanotechnology has recently increased enormously. This is due to numerous possible applications of nanomaterials in catalysis, optics, electronics, and even health protection. Many applications of silver and gold nanoparticles are possible because of their plasmonic properties. As an example of the plasmonic application of Au and Ag metal nanoparticles one can mention construction of devices for light concentration at the nanometer scale. Such deep-subwavelength optical energy concentrators are used, for example, in surface-enhanced Raman scattering (SERS) to increase the Raman signal by even 10 orders of magnitude, thus facilitating the optical identification of single molecules. Large increase in local field intensity also strongly enhances nonlinear scattering, which can be potentially useful for optical signal processing. In this article we review photochemical synthesis of silver and gold nanoparticles, especially those methods of synthesis which are driven by surface plasmon resonance (SPR) excited in Ag and Au nanoparticles. The most important step of the SPR-driven synthesis of nanoparticles is photocatalytical reduction of metal ions which occurs preferentially at such places of the nanoparticles, at which strong surface plasmons are excited (for example corners, etches). Therefore, during the grown of the nanoparticle, its anisotropy may increase. If the SPR of the seed particles is not excited – due to either the absence of photostimulation or a mismatch between the excitation wavelength and the SPR of the seeds – the deposition of metal does not occur. Therefore, SPR of nanoparticles may be also responsible for wavelength controlled size effects in the synthesis: as the nanoparticles grow and their SPRs shift from the excitation wavelength, the nanoparticles absorb less light and their growth slows. This allows for synthesis of very homogeneous samples of nanoparticles, which may be applied, for example, in various plasmonic sensors.
    Źródło:
    Wiadomości Chemiczne; 2015, 69, 3-4; 171-195
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Zastosowanie nanocząstek srebra w laserowej spektrometrii mas oraz w obrazowaniu MS : przegląd
    Application of silver nanostructures in laser desorption/ionization mass spectrometry and mass spectrometry imaging
    Autorzy:
    Sekuła, J.
    Nizioł, J.
    Ruman, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/172137.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    związki niskocząsteczkowe
    spektrometria mas
    obrazowanie spektrometrią mas
    matryca
    układy bezmatrycowe
    nanocząstki srebra
    low molecular weight compounds
    mass spectrometry
    mass spectrometry imaging
    matrices
    matrix free-system
    silver nanoparticles
    Opis:
    Metallic nanoparticles, especially silver nanoparticles, have attracted much attention due to their unique physical, chemical and opto-electronic properties. Silver nanoparticles have been successfully applied as a matrix replacement for the laser desorption/ionization time-of-flight mass spectrometry (LDI-ToF-MS). Silver nanoparticles (AgNPs) can efficiently absorb ultraviolet laser radiation, transfer energy to the analyte and promote analyte desorption, but also constitute a source of silver ions suitable for analyte cationisation. Nanoparticles, producing spectra with highly reduced chemical background in the low m/z region, are perfectly suited for low-molecular weight compound analysis and imaging. AgNPs have been demonstrated to allow efficient capture of different chemical compounds (including amino acids, cholesterol, fatty acids) on their surface, thus efficiently promoting their desorption and gas phase cationisation. The minimum detectable amount for those organic and biological molecules is often in the fmol range [23]. Despite the fact that scientists have developed a variety of methods for the synthesis of silver nanoparticles, there are still problems with obtaining surfaces with nanoparticles of high durability and chemical purity. Recently, a successful application of cationic silver nanoparticles (AgNPs), which were placed on MALDI targets for highly sensitive detection of d-ribose at attomolar levels as well as analysis of biological samples such as urine and blood serum [51] was shown. The application of new 109AgNPET surface has been presented with examples of analysis of nucleosides and nucleic bases [60]. One of the main directions of development of LDI-MS is the imaging mass spectrometry (MSI), enabling the visualization of surface distribution of biological samples. The critical limitations of the spatial resolution of MALDI-MSI are the size of the organic matrix crystals and the analyte migration during the matrix application process. To overcome these problems, researchers tried to use nanoparticles as substitutes of organic matrices. In 2013 Ruman group presented that direct contact of the analysed object with Ag nanoparticle-covered target permits direct surface transfer of chemical compounds. The active surface becomes then a “chemical photograph” of an object and allows MS analysis and MS imaging [68].
    Źródło:
    Wiadomości Chemiczne; 2016, 70, 7-8; 519-539
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Gold catalysts supported on zeolites
    Katalizatory złotowe osadzone na zeolitach
    Autorzy:
    Walkowiak, Adrian
    Powiązania:
    https://bibliotekanauki.pl/articles/2057912.pdf
    Data publikacji:
    2021
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    heterogeniczne katalizatory złotowe
    nanocząstki złota
    zeolity
    metody modyfikacji zeolitów złotem
    zastosowanie zeolitów modyfikowanych złotem
    proces katalityczny
    heterogeneous gold catalysts
    gold nanoparticles
    zeolites
    methods of zeolites modification with gold
    application of gold-modified zeolites
    catalytic process
    Opis:
    Heterogeneous gold catalysis is a relatively young but dynamically developing field of chemistry. At the end of the 1980s, Masatake Haruta and Graham Hutchings provided experimental evidence of high activity of supported gold catalysts in CO oxidation and acetylene hydrochlorination. Thus, these two researchers challenged the prevailing chemists’ belief that gold is almost completely chemically inert and catalytically inactive. Since then, gold catalysis has been constantly in the centre of attention of a wide array of scientists from around the world. However, there are still many questions about the nature of catalysts containing this noble metal, which inspires in-depth research in this field. From among various potential supports for gold heterogeneous catalysts, zeolites have drawn much attention thanks to several unique properties of this group of materials, among which the most important are high thermal stability and the presence of a system of pores of strictly defined sizes. Zeolites have extremely large surface area, which is desirable to obtain high dispersion of the active phase. The article provides a concise overview of the methods of gold nanoparticles deposition on zeolitic supports and catalytic applications of such materials. The first chapter sheds light on the properties of bulk and nano-sized Au and depicts the background of gold catalysis development. In the following part, a brief description of zeolites and their properties is delivered. The third chapter is devoted entirely to the description of several preparation methods of zeolite-supported gold catalysts and their applications in different catalytic processes. The following post-synthetic methods of zeolite modification with gold are described: impregnation, ion exchange, deposition-reduction, chemical vapour deposition, and grafting. The most important advantages and disadvantages of each method are summarized. The article concludes with a résumé of literature reports concerning the use of zeolitesupported gold catalysts in various processes. Special attention was paid to selective oxidation of alcohols and biomass-derived chemicals (e.g. glucose).
    Źródło:
    Wiadomości Chemiczne; 2021, 75, 11-12; 1259--1293
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-11 z 11

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