Showing papers on "Fluorescence spectrometry published in 2013"

Synthesis, Surface Modification and Characterisation of Biocompatible Magnetic Iron Oxide Nanoparticles for Biomedical Applications

Abstract: Superparamagnetic iron oxide nanoparticles (MNPs) with appropriate surface chemistry exhibit many interesting properties that can be exploited in a variety of biomedical applications such as magnetic resonance imaging contrast enhancement, tissue repair, hyperthermia, drug delivery and in cell separation. These applications required that the MNPs such as iron oxide Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) having high magnetization values and particle size smaller than 100 nm. This paper reports the experimental detail for preparation of monodisperse oleic acid (OA)-coated Fe3O4 MNPs by chemical co-precipitation method to determine the optimum pH, initial temperature and stirring speed in order to obtain the MNPs with small particle size and size distribution that is needed for biomedical applications. The obtained nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray fluorescence spectrometry (EDXRF), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), and vibrating sample magnetometer (VSM). The results show that the particle size as well as the magnetization of the MNPs was very much dependent on pH, initial temperature of Fe2+ and Fe3+ solutions and steering speed. The monodisperse Fe3O4 MNPs coated with oleic acid with size of 7.8 ± 1.9 nm were successfully prepared at optimum pH 11, initial temperature of 45 °C and at stirring rate of 800 rpm. FTIR and XRD data reveal that the oleic acid molecules were adsorbed on the magnetic nanoparticles by chemisorption. Analyses of TEM show the oleic acid provided the Fe3O4 particles with better dispersibility. The synthesized Fe3O4 nanoparticles exhibited superparamagnetic behavior and the saturation magnetization of the Fe3O4 nanoparticles increased with the particle size.

Green biosynthesis and characterization of magnetic iron oxide (Fe₃O₄) nanoparticles using seaweed (Sargassum muticum) aqueous extract.

Abstract: The synthesis of nanoparticles has become a matter of great interest in recent times due to their various advantageous properties and applications in a variety of fields. The exploitation of different plant materials for the biosynthesis of nanoparticles is considered a green technology because it does not involve any harmful chemicals. In this study, iron oxide nanoparticles (Fe3O4-NPs) were synthesized using a rapid, single step and completely green biosynthetic method by reduction of ferric chloride solution with brown seaweed (BS, Sargassum muticum) water extract containing sulphated polysaccharides as a main factor which acts as reducing agent and efficient stabilizer. The structural and properties of the Fe3O4-NPs were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray fluorescence spectrometry (EDXRF), vibrating sample magnetometry (VSM) and transmission electron microscopy. The average particle diameter as determined by TEM was found to be 18 ± 4 nm. X-ray diffraction showed that the nanoparticles are crystalline in nature, with a cubic shape. The nanoparticles synthesized through this biosynthesis method can potentially useful in various applications.

Heavy Metals, Major Metals, Trace Elements

Abstract: CONTENTS 11.1 Sampling 278 11.2 Storage and Preservation 279 11.3 Pretreatment of Samples 280 11.4 Digestion of Samples 281 11.5 Analytical Methods 28211.5.1 Classical Methods 282 11.5.2 Spectrophotometric Method 284 11.5.3 Flame Atomic Absorption SpectroscopyTechniques 285 11.5.4 Electrothermal Atomic Absorption Spectroscopy 286 11.5.5 Inductively Coupled Plasma Methods 287 11.5.6 Electrochemical Methods 28811.5.6.1 Voltammetric Techniques. 288 11.5.6.2 Potentiometric Techniques 28911.5.7 Ion Chromatography 289 11.5.7.1 Other Chromatographic Techniques 29011.5.8 Other Techniques 290 11.5.8.1 Luminescence 290 11.5.8.2 X-Ray Fluorescence Spectrometry 291 11.5.8.3 Neutron Activation Analysis 29111.5.9 The Particular Case of Mercury 291 11.6 Summary 292 Abbreviations 292 References 293Natural waters contamination is a worldwide distributed problem which deserves large attention not only due to its environmental hazardous effects but also for the risks to the human health as well as the economical damages it produces. Between the wide diversity of pollutants affecting water resources heavy metals receive particular concern considering their strong toxicity even at low concentrations.

Chemical fingerprinting of naphthenic acids and oil sands process waters—A review of analytical methods for environmental samples

Abstract: This article provides a review of the routine methods currently utilized for total naphthenic acid analyses. There is a growing need to develop chemical methods that can selectively distinguish compounds found within industrially derived oil sands process affected waters (OSPW) from those derived from the natural weathering of oil sands deposits. Attention is thus given to the characterization of other OSPW components such as oil sands polar organic compounds, PAHs, and heavy metals along with characterization of chemical additives such as polyacrylamide polymers and trace levels of boron species. Environmental samples discussed cover the following matrices: OSPW containments, on-lease interceptor well systems, on- and off-lease groundwater, and river and lake surface waters. There are diverse ranges of methods available for analyses of total naphthenic acids. However, there is a need for inter-laboratory studies to compare their accuracy and precision for routine analyses. Recent advances in high- and medium-resolution mass spectrometry, concomitant with comprehensive mass spectrometry techniques following multi-dimensional chromatography or ion-mobility separations, have allowed for the speciation of monocarboxylic naphthenic acids along with a wide range of other species including humics. The distributions of oil sands polar organic compounds, particularly the sulphur containing species (i.e., OxS and OxS2) may allow for distinguishing sources of OSPW. The ratios of oxygen- (i.e., Ox) and nitrogen-containing species (i.e., NOx, and N2Ox) are useful for differentiating organic components derived from OSPW from natural components found within receiving waters. Synchronous fluorescence spectroscopy also provides a powerful screening technique capable of quickly detecting the presence of aromatic organic acids contained within oil sands naphthenic acid mixtures. Synchronous fluorescence spectroscopy provides diagnostic profiles for OSPW and potentially impacted groundwater that can be compared against reference groundwater and surface water samples. Novel applications of X-ray absorption near edge spectroscopy (XANES) are emerging for speciation of sulphur-containing species (both organic and inorganic components) as well as industrially derived boron-containing species. There is strong potential for an environmental forensics application of XANES for chemical fingerprinting of weathered sulphur-containing species and industrial additives in OSPW.

Optical techniques for the noninvasive diagnosis of skin cancer

Abstract: Purpose The aim of this paper is to provide an overview of the most investigated optical diagnostic techniques: optical coherence tomography, fluorescence spectrometry, reflectance spectrometry, Raman spectroscopy, and confocal microscopy.

Characterization of Flavin-Based Fluorescent Proteins: An Emerging Class of Fluorescent Reporters

Abstract: Fluorescent reporter proteins based on flavin-binding photosensors were recently developed as a new class of genetically encoded probes characterized by small size and oxygen-independent maturation of fluorescence. Flavin-based fluorescent proteins (FbFPs) address two major limitations associated with existing fluorescent reporters derived from the green fluorescent protein (GFP)–namely, the overall large size and oxygen-dependent maturation of fluorescence of GFP. However, FbFPs are at a nascent stage of development and have been utilized in only a handful of biological studies. Importantly, a full understanding of the performance and properties of FbFPs as a practical set of biological probes is lacking. In this work, we extensively characterize three FbFPs isolated from Pseudomonas putida, Bacillus subtilis, and Arabidopsis thaliana, using in vitro studies to assess probe brightness, oligomeric state, maturation time, fraction of fluorescent holoprotein, pH tolerance, redox sensitivity, and thermal stability. Furthermore, we validate FbFPs as stable molecular tags using in vivo studies by constructing a series of FbFP-based transcriptional constructs to probe promoter activity in Escherichia coli. Overall, FbFPs show key advantages as broad-spectrum biological reporters including robust pH tolerance (4–11), thermal stability (up to 60°C), and rapid maturation of fluorescence (<3 min.). In addition, the FbFP derived from Arabidopsis thaliana (iLOV) emerged as a stable and nonperturbative reporter of promoter activity in Escherichia coli. Our results demonstrate that FbFP-based reporters have the potential to address key limitations associated with the use of GFP, such as pH-sensitive fluorescence and slow kinetics of fluorescence maturation (10–40 minutes for half maximal fluorescence recovery). From this view, FbFPs represent a useful new addition to the fluorescent reporter protein palette, and our results constitute an important framework to enable researchers to implement and further engineer improved FbFP-based reporters with enhanced brightness and tighter flavin binding, which will maximize their potential benefits.

Dispersive micro solid-phase extraction using multiwalled carbon nanotubes combined with portable total-reflection X-ray fluorescence spectrometry for the determination of trace amounts of Pb and Cd in water samples

Abstract: In this paper the combination of dispersive micro solid-phase extraction (DMSPE), using multiwalled carbon nanotubes (MWCNTs) as solid sorbents, with total-reflection X-ray fluorescence spectrometry (TXRF) is proposed for preconcentration and determination of lead and cadmium ions in water samples. The proposed sample preparation is quite simple and economic. After the sorption processes of the metals on the MWCNTs, the aqueous sample is separated by centrifugation and the metal loaded MWCNTs are suspended using a small volume of an internal standard solution and analyzed directly by TXRF. Parameters affecting the extraction process (complexing agent, pH of the aqueous sample, amount of MWCNTs) and TXRF analysis (volume of the deposited suspension on the reflector, drying mode, and instrumental parameters) have been carefully evaluated to test the real capability of the developed methodology for the determination of Cd and Pb at trace levels. For both elements the linear range is observed up to 50 ng mL−1. Under optimized conditions detection limits are 1.0 ng mL−1 and 2.1 ng mL−1 for Cd(II) and Pb(II) ions, respectively. Both of the examined elements can be determined with quantitative recoveries (ca. 100%) and with an adequate precision (RSD = 6.0% and 10.5% for Cd(II) and Pb(II), respectively). Our results give insight into the possibilities of the combination of DMSPE and TXRF for trace metal determination in different types of environmental waters (sea, river and waste water).

A novel selenocystine-accumulating plant in selenium-mine drainage area in Enshi, China.

Abstract: Plant samples of Cardamine hupingshanesis (Brassicaceae), Ligulariafischeri (Ledeb.) turcz (Steraceae) and their underlying top sediments were collected from selenium (Se) mine drainage areas in Enshi, China. Concentrations of total Se were measured using Hydride Generation-Atomic Fluorescence Spectrometry (HG-AFS) and Se speciation were determined using liquid chromatography/UV irradiation-hydride generation-atomic fluorescence spectrometry (LC-UV-HG-AFS). The results showed that C. hupingshanesis could accumulate Se to 239±201 mg/kg DW in roots, 316±184 mg/kg DW in stems, and 380±323 mg/kg DW in leaves, which identifies it as Se secondary accumulator. Particularly, it could accumulate Se up to 1965±271 mg/kg DW in leaves, 1787±167 mg/kg DW in stem and 4414±3446 mg/kg DW in roots, living near Se mine tailing. Moreover, over 70% of the total Se accumulated in C. hupingshanesis were in the form of selenocystine (SeCys2), increasing with increased total Se concentration in plant, in contrast to selenomethionine (SeMet) in non-accumulators (eg. Arabidopsis) and secondary accumulators (eg. Brassica juncea), and selenomethylcysteine (SeMeCys) in hyperaccumulators (eg. Stanleya pinnata). There is no convincing explanation on SeCys2 accumulation in C. hupingshanesis based on current Se metabolism theory in higher plants, and further study will be needed.

Assessment of heavy metal contamination in soils around chromite mining areas, Nuggihalli, Karnataka, India

Abstract: Toxic heavy metals represent one of the possible environmental hazards from mine lands, which affect many countries having historic mining industries. The primary aim of the study was to investigate the degree of soil pollution occurring near chromite mines, and make a systematic evaluation of soil contamination based on geoaccumulation index, enrichment factor and pollution index. This paper presents the pollution load of toxic heavy metals (As, Ba, Co, Cr, Cu, Mo, Ni, Pb, Sr, V, Zn and Zr) in 57 soil samples collected around three different active (Tagdur), abandoned (Jambur) chromite mining sites as well residential zone around Chikkondanahalli of the Nuggihalli Schist Belt, Karnataka, India. Soil samples were analyzed for heavy metals by using Wavelength dispersive X-ray fluorescence spectrometry. Results indicated that elevated concentrations of Cr, Ni and Co in soils of the study area exceed the Soil Quality Guideline limits (SQGL). The high enrichment factor for Cr, Ni Co obtained in the soil samples show that there is a steady increase of toxic heavy metals risk in this area, which could be correlated with the past mining activity and post abandoned mining in the area. The data was also treated to study the geoaccumulation index, pollution index and spatial distribution of toxic elements. Emphasis need to be put on control measures of pollution and remediation techniques in the study area.

Graphene oxide as a solid sorbent for the preconcentration of cobalt, nickel, copper, zinc and lead prior to determination by energy-dispersive X-ray fluorescence spectrometry

Abstract: A new method for sample preparation using graphene oxide (GO) as a novel sorbent was developed for the preconcentration of trace amounts of Co(II), Ni(II), Cu(II), Zn(II) and Pb(II). The proposed preconcentration procedure is based on dispersive micro-solid phase extraction (DMSPE). It means that GO was dispersed in aqueous samples containing trace elements to be determined. During the stirring of the analyte solution containing the GO suspension, metal ions were sorbed by GO. After the sorption, the solution was filtered under vacuum and GO with the metal ions was collected onto a membrane filter. The obtained samples were analyzed directly by energy-dispersive X-ray fluorescence spectrometry (EDXRF). The parameters affecting the extraction and preconcentration process were optimized. The pH of the analyte solution, the amount of GO, the sample volume, the contact time between analytes and sorbent (stirring time), and the effects of foreign metals are discussed in detail in this paper. The proposed procedure allows us to obtain the detection limits of 0.5, 0.7, 1.5, 1.8 and 1.4 ng mL−1 for Co(II), Ni(II), Cu(II), Zn(II) and Pb(II), respectively. The linearity of the method is in the range of 5–100 ng mL−1. The proposed method was successfully applied in the analysis of water. The accuracy of the method was verified using spiked samples and inductively coupled plasma optical emission spectrometry (ICP-OES) as a comparative technique. The recoveries over the range of 94–106% were obtained. This paper shows the great potential of GO as an excellent sorbent in the preconcentration field of analytical chemistry. The proposed method meets green chemistry rules.

Occurrence of brominated flame retardants in black thermo cups and selected kitchen utensils purchased on the European market

Abstract: In order to screen for the presence of a recycled polymer waste stream from waste electric and electronic equipment (WEEE), a market survey was conducted on black plastic food-contact articles (FCA). An analytical method was applied combining X-ray fluorescence spectrometry (XRF) with thermal desorption gas chromatography coupled with mass spectrometry (thermal desorption GC-MS). Firstly, XRF spectrometry was applied to distinguish bromine-positive samples. Secondly, bromine-positive samples were submitted for identification by thermal desorption GC-MS. Generally, the bromine-positive samples contained mainly technical decabromodiphenyl ether (decaBDE). Newer types of BFRs such as tetrabromobisphenol A (TBBPA), tetrabromobisphenol A bis(2,3-dibromopropyl), ether (TBBPA-BDBPE) and decabromodiphenylethane (DBDPE), replacing the polybrominated diphenyleters (PBDEs) and polybrominated diphenyls (PBBs), were also identified. In none of the tested samples were PBBs or hexabromocyclododecane (HBCD) found. Polymer identification was carried out using Fourier-transformed infrared spectroscopy measurement (FTIR) on all samples. The results indicate that polypropylene-polyethylene copolymers (PP-PE) and mainly styrene-based food-contact materials, such as acrylonitrile-butadiene-styrene (ABS) have the highest risk of containing BFRs.

Secondary organic aerosol formation from the oxidation of a series of sesquiterpenes: α-cedrene, β-caryophyllene, α-humulene and α-farnesene with O3, OH and NO3 radicals

Abstract: Environmental context Sesquiterpenes, chemicals emitted by terrestrial vegetation, are oxidised in the ambient atmosphere leading to the formation of secondary organic aerosol. Although secondary organic aerosol can have significant effects on air quality from local to global scales, considerable gaps remain in our understanding of their various sources and formation mechanisms. We report studies on the oxidation of sesquiterpenes aimed at improving aerosol parameterisation for these reactions for incorporation into future air quality models. Abstract A series of sesquiterpenes (SQT) were individually oxidised under a range of conditions, including irradiation in the presence of NOx, reactions with O3 or reactions with NO3 radicals. Experiments were conducted in either static mode to observe temporal evolution of reactants and products or in dynamic mode to ensure adequate collection of aerosol at reasonably low reactant concentrations. Although some measurements of gas-phase products have been made, the focus of this work has been particle phase analysis. To identify individual products, filter samples were extracted, derivatised and analysed using gas chromatography mass spectrometry techniques. The results indicate that secondary organic aerosol (SOA) is readily formed from SQT oxidation. The high reactivity of these systems and generally high conversion into SOA products gives rise to high SOA levels. SOA yields (ratio of SOA formed to hydrocarbon reacted) averaged 0.53 for ozonolysis, 0.55 for photooxidation and 1.19 for NO3 reactions. In select experiments, SOA was also analysed for the organic matter/organic carbon (OM/OC) ratio, and the effective enthalpy of vaporisation (ΔHvapeff). The OM/OC ranged from 1.8 for ozonolysis and photooxidation reactions to 1.6 for NO3 reactions, similar to that from SOA generated in monoterpene systems. ΔHvapeff was measured for β-caryophyllene–NOx, β-caryophyllene–O3, β-caryophyllene–NO3, α-humulene–NOx and α-farnesene–NOx systems and found to be 43.9, 41.1, 44.9, 48.2 and 27.7 kJ mol–1. Aerosol yields and products identified in this study are generally in good agreement with results from several studies. A detailed examination of the chamber aerosol for the presence of chemical tracer compounds was undertaken. Only β-caryophyllinic acid, observed mainly under β-caryophyllene photooxidation and ozonolysis experiments, was detected in ambient aerosol. Chemical analysis yielded compounds having oxygen and nitrogen moieties present, which indicates continued evolution of the particles over time and presents high dependence on the SQT–oxidant system studied. This study suggests that SOA from laboratory ozonolysis experiments may adequately represent ambient aerosol in areas with SQT emissions.

Identification of Metal-Associated Proteins in Cells by Using Continuous-Flow Gel Electrophoresis and Inductively Coupled Plasma Mass Spectrometry

Abstract: Metals and metalloids are crucial for life and indispensable for a series of biological processes. It is estimated that a quarter to one third of all proteins require metals to carry out their functions, and roughly half of the known enzymes uses a particular metal as a cofactor. In spite of the prevalence and importance of metalloproteins, they are generally poorly characterized in many organisms. A recent study demonstrated that the microbial metalloproteome is much more extensive and diverse than we presently know. Currently, it is impossible to predict, genome-wide, the numbers and types of metals used by organisms and to define any metalloproteome until the proteins are fully characterized owing to diverse and poorly recognized metal coordination sites. Moreover, metals/metalloids have long been used for therapeutic purposes, for example, arsenic trioxide for the treatment of acute promyelocytic leukemia. The detailed molecular mechanisms, however, are still not fully understood owing to the complex functions of metals in biological systems. A robust and convenient approach, by which metals/metalloids can be mapped to their associated proteins proteome-wide is urgently needed. Such a methodology will improve our understanding of the molecular mechanisms of metal-dependent biological processes and profoundly promote metallomics research, an integrated biometal science complementary to genomics and proteomics. Gel electrophoresis has been one of the commonly used methods for separation and analysis of proteins based on their molecular mass and charge; however, it fails to provide information on metal identity and content for metalloproteins. The lack of convenient subsequent methods for specific metal detection confines its application on providing metalrelated information of corresponding proteins. Although laser ablation inductively coupled plasma mass spectrometry (LAICP-MS) and synchrotron X-ray fluorescence spectrometry (SXFS) have been used for the identification of metalbinding proteins on gels and in tissues/organs, either compromised sensitivity originating from the sample introduction system or limited accessibility to the synchrotron facility prevents their routine applications. Other strategies such as metal isotope radioautography, which employs unique metal isotopes to label metalloproteins, are also very inconvenient for daily usage. Herein, a new strategy based on column-type gel electrophoresis coupled with a metal-specific detection system, that is ICP-MS, was developed (Figure 1a), allowing both metals and their associated proteins to be examined comprehensively. Since the strategy can be used to analyze and at the same time to separate and isolate proteins, it can readily be applied to not only detect metalloproteins and/or metalbound proteins with a sensitivity at the femtomole level, but also conveniently integrate current proteomics with metallomics. We further showed the bismuth profile in cell lysates of Helicobacter pylori upon treatment with colloidal bismuth subcitrate (CBS) and further characterized metal-binding features of H. pylori SlyD (HpSlyD) inside cells. The column-type gel adopted the traditional slab gel preparation. Both native and denaturing conditions could be applied, and the gel compositions varied with the protein targets of interest. To validate the feasibility of the column gel system, three metal-binding proteins, Cu-bound bovine serum albumin (Cu-BSA), Cu,Zn superoxide dismutase (Cu,ZnSOD), and diferric transferrin (Fe2-Tf), were mixed and subjected to separation. Three bands, corresponding to Fe2Tf, Cu,Zn-SOD, and BSA, were visualized on a CoomassieBlue-stained slab gel (Figure 1b). The proteins separated by column-type gel electrophoresis gave rise to migration profiles similar to those observed in classical slab gel under comparable conditions. The elutes from the column gel system were split into two parts by using a T connection, with one for online metal measurement by ICP-MS and the other for protein identification through biological mass spectrometry analysis of the collected fractions (Figure 1a). It is noted that one peak was observed in either the Zn or Fe profile corresponding to SOD and transferrin, respectively, indicative of association of Zn ions with SOD and binding of Fe ions to Tf; whereas there are two peaks in the Cu profile, with each corresponding to a distinct molecular mass, thus suggesting that copper binds to both SOD and BSA. The amounts of metals were quantifiable (Figure S2 in [*] Dr. L. Hu, Dr. T. Cheng, Dr. B. He, Y. Wang, Y.-T. Lai, Prof. H. Sun Department of Chemistry, The University of Hong Kong Pokfulam, Hong Kong (P. R. China) E-mail: hsun@hku.hk

Agglomeration and dissolution of zinc oxide nanoparticles: role of pH, ionic strength and fulvic acid

Abstract: Environmental context The number of nano-enabled products reaching consumers is growing exponentially, inevitably resulting in their release to the environment. The environmental fate and mobility of nanomaterials will depend on their physicochemical form(s) under natural conditions. For ZnO nanoparticles, determinations of agglomeration and dissolution under environmentally relevant conditions of pH, ionic strength and natural organic matter content will provide insight into the potential environmental risk of these novel products. Abstract The increasing use of engineered nanoparticles (ENPs) in industrial and household applications has led to their release into the environment and increasing concern about their effects. Proper assessment of the ecological risks of ENPs will require data on their bioavailability, persistence and mobility over a broad range of physicochemical conditions, including environmentally relevant pH, ionic strength and concentrations of natural organic matter (NOM). In this study, fluorescence correlation spectroscopy was used to determine the agglomeration of a ZnO ENP (nZnO) with a nominal size of 20nm. Particle dissolution was followed using scanned stripping chronopotentiometry. The effects of Suwannee River fulvic acid (SRFA, 0–60mgL–1) and the roles of pH (4–10) and ionic strength (0.005–0.1M) were carefully evaluated. Agglomeration of the bare nZnO increased for pH values near the zero point of charge, whereas the dissolution of the particles decreased. At any given pH, an increase in ionic strength generally resulted in a less stable colloidal system. The role of SRFA was highly dependent upon its concentration with increased agglomeration observed at low SRFA : nZnO mass ratios and decreased agglomeration observed at higher SRFA : nZnO mass ratios. The results indicated that in natural systems, both nZnO dispersion and dissolution will be important and highly dependent upon the precise conditions of pH and ionic strength.

Determination of Cadmium in Biological Samples

Abstract: Analyses of cadmium concentrations in biological material are performed using inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS), but also electrochemical methods, neutron activation analysis (NAA), and X-ray fluorescence spectrometry (XRF) The predominant sample matrices include blood, plasma, serum, and urine, as well as hair, saliva, and tissue of kidney cortex, lung, and liver While cadmium in blood reveals rather the recent exposure situation, cadmium in urine reflects the body burden and is an indicator for the cumulative long term exposure

VCAM-1-targeted core/shell nanoparticles for selective adhesion and delivery to endothelial cells with lipopolysaccharide-induced inflammation under shear flow and cellular magnetic resonance imaging in vitro.

Abstract: Multifunctional nanomaterials with unique magnetic and luminescent properties have broad potential in biological applications. Because of the overexpression of vascular cell adhesion molecule-1 (VCAM-1) receptors in inflammatory endothelial cells as compared with normal endothelial cells, an anti-VCAM-1 monoclonal antibody can be used as a targeting ligand. Herein we describe the development of multifunctional core-shell Fe3O4@SiO2 nanoparticles with the ability to target inflammatory endothelial cells via VCAM-1, magnetism, and fluorescence imaging, with efficient magnetic resonance imaging contrast characteristics. Superparamagnetic iron oxide and fluorescein isothiocyanate (FITC) were loaded successfully inside the nanoparticle core and the silica shell, respectively, creating VCAM-1-targeted Fe3O4@SiO2(FITC) nanoparticles that were characterized by scanning electron microscopy, transmission electron microscopy, fluorescence spectrometry, zeta potential assay, and fluorescence microscopy. The VCAM-1-targeted Fe3O4@SiO2(FITC) nanoparticles typically had a diameter of 355 ± 37 nm, showed superparamagnetic behavior at room temperature, and cumulative and targeted adhesion to an inflammatory subline of human umbilical vein endothelial cells (HUVEC-CS) activated by lipopolysaccharide. Further, our data show that adhesion of VCAM-1-targeted Fe3O4@SiO2(FITC) nanoparticles to inflammatory HUVEC-CS depended on both shear stress and duration of exposure to stress. Analysis of internalization into HUVEC-CS showed that the efficiency of delivery of VCAM-1-targeted Fe3O4@SiO2(FITC) nanoparticles was also significantly greater than that of nontargeted Fe3O4@SiO2(FITC)-NH2 nanoparticles. Magnetic resonance images showed that the superparamagnetic iron oxide cores of the VCAM-1-targeted Fe3O4@SiO2(FITC) nanoparticles could also act as a contrast agent for magnetic resonance imaging. Taken together, the cumulative adhesion and uptake potential of these VCAM-1-targeted Fe3O4@SiO2(FITC) nanoparticles targeted to inflammatory endothelial cells could be used in the transfer of therapeutic drugs/genes into these cells or for diagnosis of vascular disease at the molecular and cellular levels in the future.

X-Ray Fluorescence Spectrometry and Related Techniques : An Introduction

Abstract: X-ray fluorescence spectrometry (XRF) is a well-established analytical technique for qualitative and quantitative elemental analysis of a wide variety of materials. It is known for its rapid speed and ease of use. All levels of professionals in materials science, analytic chemistry, and physics will benefit from the review of basic and newly developed technologies presented in this book. Highlights include: A basic introduction to XRF, including background on X-ray physics. Coverage of qualitative and quantitative analysis using XRF. Coverage of the design of low-power micro-focus tubes and novel X-ray optics and detectors. Benchtop and portable instrumentation that offer extreme simplicity of operation in a low-cost design. Extensive bibliographic references. Buyers Guide.

Spatial distribution of potentially bioavailable metals in surface soils of a contaminated sports ground in Galway, Ireland.

Abstract: Assessing the environmental risk of metal contamination in soils requires the determination of both total (TCs) and bioavailable (BCs) element concentrations. A total of 200 surface (0–10 cm) soil samples were collected from an urban sports ground (South Park) in Galway, Ireland, a former landfill and dumping site, which is currently under remediation. The potential BCs of metals were measured using ethylene-diamine-tetra-acetic acid (EDTA) extraction followed by inductively coupled plasma-optical emission spectrometry analysis, while the TCs were determined using portable X-ray fluorescence spectrometry. It was found that Zn was primarily present in the insoluble residue (EDTA un-extractable) fraction in soils, with the median ratio of BCs/TCs 0.27. However, Pb and Cu had higher ratios of BCs/TCs (median values of 0.60 and 0.39, respectively) suggesting that they are potentially more bioavailable in the soils. The spatial distribution maps showed that both TCs and BCs for Cu, Pb and Zn in the study area were spatially heterogeneous. It was found that the BCs exhibited generally similar spatial patterns as their TCs of Cu, Pb and Zn: high values were mainly located in the west, north-east and south-east portions of the study area, where only a thin layer of topsoil existed. It was recommended that the current remediation action for this site needs to be carried out on an urgent basis.

Development of fast, simultaneous and multi-technique scanning hard X-ray microscopy at Synchrotron Soleil

Abstract: A distributed fast-acquisition system for synchronized multi-technique experiments is presented, in which the collection of metadata and the asynchronous merging of large data volumes from multiple detectors are managed as part of the data collection process. This fast continuous scanning scheme, named FLYSCAN, enables measurement of microscopy data on a timescale of milliseconds per pixel. Proof-of-principle multi-technique experiments, namely scanning X-ray fluorescence spectrometry combined with absorption, differential phase contrast and dark-field imaging, have been performed on biological and geological samples.

Fucoxanthin Protects Cultured Human Keratinocytes against Oxidative Stress by Blocking Free Radicals and Inhibiting Apoptosis.

Abstract: Fucoxanthin is an important carotenoid derived from edible brown seaweeds and is used in indigenous herbal medicines. The aim of the present study was to examine the cytoprotective effects of fucoxanthin against hydrogen peroxide-induced cell damage. Fucoxanthin decreased the level of intracellular reactive oxygen species, as assessed by fluorescence spectrometry performed after staining cultured human HaCaT keratinocytes with 2',7'-dichlorodihydrofl uorescein diacetate. In addition, electron spin resonance spectrometry showed that fucoxanthin scavenged hydroxyl radical generated by the Fenton reaction in a cell-free system. Fucoxanthin also inhibited comet tail formation and phospho-histone H2A.X expression, suggesting that it prevents hydrogen peroxideinduced cellular DNA damage. Furthermore, the compound reduced the number of apoptotic bodies stained with Hoechst 33342, indicating that it protected keratinocytes against hydrogen peroxide-induced apoptotic cell death. Finally, fucoxanthin prevented the loss of mitochondrial membrane potential. These protective actions were accompanied by the down-regulation of apoptosispromoting mediators (i.e., B-cell lymphoma-2-associated x protein, caspase-9, and caspase-3) and the up-regulation of an apoptosis inhibitor (B-cell lymphoma-2). Taken together, the results of this study suggest that fucoxanthin defends keratinocytes against oxidative damage by scavenging ROS and inhibiting apoptosis.