Nanoparticles as multimodal photon transducers of ionizing radiation

In biomedical imaging, nanoparticles combined with radionuclides that generate Cerenkov luminescence are used in diagnostic imaging, photon-induced therapies, and as activatable probes. In these applications, the nanoparticle is often viewed as a carrier inert to ionizing radiation from the radionuclide. However, certain phenomena such as enhanced nanoparticle luminescence and generation of reactive oxygen species cannot be explained by only Cerenkov luminescence interactions with nanoparticles. Herein, we report methods to examine the mechanisms of nanoparticle excitation by radionuclides, including interactions with Cerenkov luminescence, β particles, and γ radiation. We demonstrate that β scintillation contributes appreciably to excitation and reactivity in certain nanoparticle systems and that excitation of nanoparticles composed of large atomic number atoms by radionuclides generates X-rays, enabling multiplexed imaging through single photon emission computed tomography. These findings demonstrate practical optical imaging and therapy using radionuclides with emission energies below the Cerenkov threshold, thereby expanding the list of applicable radionuclides

Potential of total-reflection X-ray spectrometry for multielement analysis of biological samples using dilution or suspension sample preparation techniques

In most clinical and nutritional studies, it is of significance to know information about the multielemental composition of biological samples. Conventional analysis of biological samples relies upon sample digestion followed by atomic spectrometry detection. This approach is essential for the quantification of ultratrace elements in biological samples. While in other applications it could be of interest to have simpler analytical methods with multielemental capability but involving a minimum sample treatment, reduce the amount of sample and a more cost-effective analysis. In the present contribution, the possibilities and drawbacks of simple sample treatments (i.e., dilution and suspension) in combination with total reflection X-ray fluorescence spectrometry (TXRF) for the analysis of different types of biological samples have been critically evaluated. For that, a set of reference materials or well-characterized biological human fluids (blood, serum, plasma and seminal plasma) and animal/vegetal tissues have been used to estimate the analytical capabilities in terms of limits of detection, trueness and precision of the proposed TXRF methods. The results are based on the authors' experience in analysing biological samples using TXRF, and it is expected that they can be useful for new TXRF users in this field and they can provide a good basis for further application of this technique in clinical studies and other applications dealing with the analysis of biological samples in the future

Simultaneous determination of silver and gold nanoparticles by cloud point extraction and total reflection X-ray fluorescence analysis

17th International Conference on Total Reflection X-Ray Fluorescence Analysis and Related Methods (TXRF) -- SEP 19-22, 2017 -- Brescia, ITALYWOS: 000453493300003While the nanoscale dimensions give metallic nanoparticles unique physical and chemical properties, their potential release in the environment and subsequent effects on ecosystem health are becoming an increasing concern. In the present contribution, for the first time, a novel and simple analytical approach has been developed for the simultaneous quantification of silver and gold nanoparticles (AgNPs, AuNPs) in aqueous samples. The method combines a sample preparation and enrichment step based on cloud point extraction (CPE) with total reflection X-ray fluorescence spectrometry (TXRF) detection. Experimental conditions enabling the simultaneous extraction and detection of AgNPs and AuNPs were studied in detail. Under the best analytical conditions, limits of detection for AgNPs and AuNPs were 0.3 and 0.2 mu g L-1, respectively. Due to the lack of suitable certified references materials, accuracy of the CPE-TXRF method was tested by analysing several types of spiked water samples, including mineral, tap, river and sea water. Percentage recoveries achieved for the analysis of spiked samples were in all cases in the range of 82-100% for both types of studied NPs, suggesting that the existence of natural colloids, ionic Ag+ and Au3+ species, and other components in environmental waters have little influence on the quantitative determination of AgNPs and AuNPs. The only exception was the recovery obtained in the analysis of the spiked sea water sample that was around 40-50%. However, for salty aqueous samples, the developed analytical approach might still be feasible if the standard addition method is used for calibration purposes. In an attempt to provide additional information on AgNPs and AuNPs behaviour in the environment, the CPE-TXRF method was also applied to study the influence of organic matter content in waters as well as the influence of soil matrix on AgNPs and AuNPs stability.Spanish Ministry of Economy and Competitiveness [CGL2013-48802-C3-2-R]; Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [1059B191600371]The Spanish Ministry of Economy and Competitiveness financed this work through the project CGL2013-48802-C3-2-R. Zekeriyya Bahadir acknowledges The Scientific and Technological Research Council of Turkey (TUBITAK) for the 2219-International Postdoctoral Research Grant (2016/1, application number: 1059B191600371) and also his own sincere gratitude to Girona University for laboratory facilities

Determination of trace amounts of hexavalent chromium in drinking waters by dispersive microsolid-phase extraction using modified multiwalled carbon nanotubes combined with total reflection X-ray fluorescence spectrometry

Soylak, Mustafa/0000-0002-1017-0244; Margui, Eva/0000-0003-4630-1530; Hidalgo, Manuela/0000-0002-4450-3772WOS: 000354155100023A methodology based on the combination of dispersive microsolid-phase extraction (DMSPE) with total reflection X-ray fluorescence (TXRF) spectrometry is proposed for the determination of hexavalent chromium in drinking waters. Multiwalled carbon nanotubes (MWCNTs) modified with the anionic exchanger tricaprylmethylammonium chloride (Aliquat 336) were used as solid sorbents. After the sorption process of Cr(VI) on the modified MWCNTs, the aqueous sample was separated by centrifugation and the loaded MWCNTs were suspended using a small volume of an internal standard solution and analyzed directly by a benchtop TXRF spectrometer, without any elution step. Parameters affecting the extraction process (pH and volume of the aqueous sample, amount of MWCNTs, extraction time) and TXRF analysis (volume of internal standard, volume of 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 Cr(VI) at trace levels. Using the best analytical conditions, it was found that the minimum Cr(VI) content that can be detected in an aqueous solution was 3 mu g L-1. This value is almost 20 times lower than the maximum hexavalent chromium content permissible in drinking waters, according to the World Health Organization (WHO). Recoveries for spiked tap and mineral water samples were, in most cases, in the range of 101-108% which demonstrates the suitability of the TXRF methodology for monitoring Cr(VI) at trace levels in drinking watersamples. (C) 2015 Elsevier B.V. All rights reserved.Spanish National Research Program [CGL2010-22168-C03-01]; Higher Education Institution (YOK) in TurkeyMinistry of National Education - TurkeyThis work was supported by the Spanish National Research Program (Project ref. CGL2010-22168-C03-01). Zekeriyya Bahadir wishes to thank the Higher Education Institution (YOK) in Turkey for the International Postgraduate Research Scholarship and also his own sincere gratitude to Girona University for laboratory facilities

Development and Application of X-rays in Metal Analysis of Soil and Plants

No abstract: Special Issue Editorial articl

Cr speciation in water samples by dispersive liquid-liquid microextraction combined with total reflection X-ray fluorescence spectrometry

Soylak, Mustafa/0000-0002-1017-0244WOS: 000369213400007A novel method based on dispersive liquid-liquid microextraction (DLLME) and total-reflection X-ray fluorescence spectrometry (TXRF) is proposed for the determination and preconcentration of inorganic Cr species (Cr(VI) and Cr(III)) in water samples. Parameters affecting the extraction procedure for Cr speciation (pH, sample volume, disperser solvent, complexing agent, organic solvent, temperature) and TXRF conditions (sample volume, drying mode, measurement time, internal standardization) have been carefully evaluated to ensure the highest sensitivity for Cr determination. It was found that the minimum Cr content that can be detected was 0.8 mu g L-1. This value is significantly lower than the maximum Cr content permissible in drinking waters and it is better or comparable with those obtained in other published works based on the use of solid phase extraction or liquid phase microextraction in combination with atomic absorption spectrometry techniques. A good linearity (R-2 = 0.9937) was obtained in the range of 5 to 4000 mu g L-1 demonstrating the suitability of the DLLME + TXRF for both the analysis of drinking and waste water samples. Additional advantages of the DLLME-TXRF systems indude the use of very small amount of reagents and the simplicity and low cost of operation of the benchtop instrument used (no cooling, media and gas consumption are needed). (C) 2015 Elsevier B.V. All rights reserved.Spanish National Research Program [CGL2010-22168-C03-01, CGL2013-48802-C3-2-R]; Higher Education Institution (YOK) in TurkeyMinistry of National Education - TurkeyThe authors want to thank the financial support for this project from the Spanish National Research Program (Project ref. CGL2010-22168-C03-01 and Project ref. CGL2013-48802-C3-2-R). Zekeriyya Bahadir acknowledges Higher Education Institution (YOK) in Turkey for the International Postgraduate Research grant and also his own sincere gratitude to Girona University for laboratory facilities

TXRF analysis of vegetal foodstuff samples

In this work, a fast and simple analytical method has been developed for the multi elemental analysis of different vegetal foodstuff samples, by using a combination of two low power benchtop total reflection X-ray fluorescence (TXRF) systems. The suspension of the powdered samples in deionized water showed to be the most suitable way for the preparation and analysis of this kind of samples. However, for comparison purposes the samples were also acid digested and measured by TXRF