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| 2. |
- Farkas, Julia, et al.
(författare)
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Characterization of the effluent from a nanosilver producing washing machine
- 2011
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Ingår i: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 37:6, s. 1057-1062
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Tidskriftsartikel (refereegranskat)abstract
- The increasing number of nanomaterial based consumer products raises concerns about their possible impact on the environment. This study provides an assessment of the effluent from a commercially available silver nanowashing machine. The washing machine released silver in its effluent at an average concentration of 11 mu g L(-1), as determined by inductive coupled mass spectrometry (ICP-MS). The presence of silver nanoparticles (AgNPs) was confirmed by single particle ICP-MS as well as ion selective electrode measurements and filtration techniques. Size measurements showed particles to be in the defined nanosize range, with an average size of 10 nm measured with transmission electron microscopy (TEM) and 60-100 nm determined with nanoparticle tracking analysis (NTA). The effluent was shown to have negative effects on a natural bacterial community as its abundance was clearly reduced when exposed to the nanowash water. If washing machines capable of producing AgNPs become a common feature of households in the future, wastewater will contain significant loadings of AgNPs which might be released into the environment.
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| 3. |
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| 4. |
- Gallego-Urrea, Julian A., 1977, et al.
(författare)
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Measurements of nanoparticle number concentrations and size distributions in contrasting aquatic environments using nanoparticle tracking analysis
- 2010
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Ingår i: Environmental Chemistry. - 1449-8979. ; 7, s. 67-81
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Tidskriftsartikel (refereegranskat)abstract
- A feasibility study of nanoparticle tracking analysis (NTA) for aquatic environmental samples is presented here. The method has certain virtues such as minimum perturbation of the samples, high sensitivity in terms of particle concentration, and provision of number-based size distributions for aquatic samples. NTA gave linear calibration curves in terms of number concentration and accurately reproduced size measurements of certified reference material nanoparticles. However, the accuracy of the size distributions obtained with this method exhibited a high dependence on set-up parameters and the concentrations were shown to be strongly correlated with the refractive index of the material under examination. Different detection cameras and different data acquisition modeswere compared and evaluated. Also, the effect of filtration of the samples was assessed. The size distributions for the contrasting environmental samples were fairly reasonable compared with other studies but an underestimation of small sizes was observed, which can be explained by a materialdependent lower detection limit in terms of size. The number concentrations obtained for the natural nanoparticles ranged from 0.5 to 20×108 particles mL−1 and correlated well with conventional turbidity measurements.
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| 6. |
- Moreira, Beatriz, et al.
(författare)
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Surface Plasmon Resonance for Measuring Exocytosis from Populations of PC12 Cells: Mechanisms of Signal Formation and Assessment of Analytical Capabilities
- 2017
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 89:5, s. 3069-3077
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Tidskriftsartikel (refereegranskat)abstract
- Because of cell to cell variation, it is difficult to obtain statistically significant data on the frequency of exocytosis events (R-exocytosis, t(-1) m(-2)) with traditional single cell electrophysiological or fluorescence microscopy based methods. Here we take the first steps toward a rapid cost-effective surface plasmon resonance (SPR) based method for measuring the R-exocytosis for populations of PC12 cells. The conditions for culturing confluent monolayers on the sensor slides were optimized, and neurotransmitter exocytosis was evoked by injecting solutions with elevated Exocytosis caused a shift of the resonance angle (Delta theta(r)) that was linearly proportional to R-exocytosis The Delta theta(r) was mainly due to elevated concentration of secretory vesicles close to the cell membrane. The increased vesicle concentration thus acted as a proxy for the Rexocytosis that could not be measured directly. The Delta theta(r) was calibrated for it R-exocytosis using single cell amperometry on parallel cell cultures. The cell populations were large enough for variation in responses between sensor slides to only reflect actual differences in biological condition. The applicability for drug screening is demonstrated by studying the effects of EGTA, reserpine, and prolonged stimulation by K+
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| 7. |
- Tuoriniemi, Jani, 1982, et al.
(författare)
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A new peak recognition algorithm for detection of ultra-small nano-particles by single particle ICP-MS using rapid time resolved data acquisition on a sector-field mass spectrometer
- 2015
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 30:8, s. 1723-1729
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Tidskriftsartikel (refereegranskat)abstract
- The applicability of single particle inductively coupled plasma mass spectrometry (spICPMS) is currently limited to particles larger than similar to 10 nm in diameter. In this work, the size detection limit (DLs) was improved by resolving the ion bursts originating from silver or gold nanoparticles (AgNPs or AuNPs) using real time data acquisition with 0.1 ms time resolution. Such acquisition is here called the Fast Acquisition Speed Technique (FAST). The analytical capabilities of the FAST were evaluated on a sector field instrument with high ion transmission efficiency (ITE). An algorithm for distinguishing particle events from dissolved and/or background signals was developed, and it was possible to detect 6.4 nm AuNPs that delivered only 2 ions to the detector. The influence of dwell time was investigated and it was concluded that the minimum DLs is achieved for dwell times close to the duration of particle events similar to 0.2 ms. Attempts to further improve the DLs should therefore be focused on increasing the ITE of the mass spectrometer.
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| 8. |
- Tuoriniemi, Jani, 1982, et al.
(författare)
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Determination of the Distance Between the Cytochrome and Dehydrogenase Domains of Immobilized Cellobiose Dehydrogenase by Using Surface Plasmon Resonance with a Center of Mass Based Model
- 2020
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 92:3, s. 2620-2627
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Tidskriftsartikel (refereegranskat)abstract
- Changes in the tertiary conformation of adsorbed biomolecules can induce detectable shifts (Delta theta(r)) in the surface plasmon resonance (SPR) angle. Here it is shown how to calculate the corresponding shifts in the adsorbate's center of mass (Delta z(avg)) along the sensing surface normal from the measured Delta theta(r). The novel developed model was used for determining the mean distance between the cytochrome (CYT) and flavodehydrogenase (DH) domains of the enzyme cellobiose dehydrogenase (CDH) isolated from the fungi Neurospora crassa, Corynascus thermophilus, and Myriococcum thermophilum as a function of pH, [Ca2+], and substrate concentration. SPR confirmed the results from earlier electrochemical and SAXS studies stating that the closed conformation, where the two domains are in close vicinity, is stabilized by a lower pH and an increased [Ca2+]. Interestingly, an increasing substrate concentration in the absence of any electron acceptors stabilizes the open conformation as the electrostatic repulsion due to the reaped electrons pushes the DH and CYT domains apart. The accuracy of distance determination was limited mostly by the random fluctuations between replicate measurements, and it was possible to detect movements <1 nm of the domains with respect to each other. The results agreed with calculations using already established models treating conformational changes as contraction or expansion of the thickness of the adsorbate layer (t(protein)). Although the models yielded equivalent results, in this case, the Delta z(avg)-based method also works in situations, where the adsorbate's mass is not evenly distributed within the layer.
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| 9. |
- Tuoriniemi, Jani, 1982, et al.
(författare)
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Determining Number Concentrations and Diameters of Polystyrene Particles by Measuring the Effective Refractive Index of Colloids Using Surface Plasmon Resonance
- 2016
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 32:41, s. 10632-10640
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Tidskriftsartikel (refereegranskat)abstract
- The capabilities of surface plasmon resonance (SPR) for characterization of colloidal particles were evaluated for 100, 300, and 460 nm nominal diameter polystyrene (PS) latexes. First the accuracy of measuring the effective refractive index (n(eff)) of turbid colloids using SPR was quantified. It was concluded that for submicrometer sized PS particles the accuracy is limited by the reproducibility between replicate injections of samples. An SPR method was developed for obtaining the particle mean diameter (d(part)) and the particle number concentration (c(p)) by fitting the measured n(eff) of polystyrene (PS) colloids diluted in series with theoretical values calculated using the coherent scattering theory (CST). The d(part) and c(p) determined using SPR agreed with reference values obtained from size distributions measured by scanning electron microscopy (SEM), and the mass concentrations stated by the manufacturer. The 100 nm particles adsorbed on the sensing surface, which hampered the analysis. Once the adsorption problem has been overcome, the developed SPR method has potential to become a versatile tool for characterization of colloidal particles. In particular, SPR could form the basis of rapid and accurate methods for measuring the c(p) of submicrometer particles in dispersion.
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| 10. |
- Tuoriniemi, Jani, 1982, et al.
(författare)
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Improving the accuracy of single particle ICPMS for measurement of size distributions and number concentrations of nanoparticles by determining analyte partitioning during nebulisation
- 2014
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 29:4, s. 743-752
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Tidskriftsartikel (refereegranskat)abstract
- Application of single particle ICP-MS (spICPMS) for measurement of the size and number concentration, c(p), of nanoparticles is currently hampered by insufficient accuracy. The relative contributions of different types of noise to the overall uncertainty during spICPMS measurements of Ag and Au nanoparticle dispersions were quantified showing that the accuracy of spICPMS is mainly limited by the uncertainty in nebulization efficiency (f(neb)). This uncertainty was improved by correcting f(neb) for analyte partitioning effects during nebulization, and the calculated Ag and Au nanoparticle sizes were in close agreement with sizes determined by scanning electron microscopy. The duration of the particle events was measured, which allowed correction for incomplete particle events and detector dead time, and determination of the effective dwell time for particle counting. The c(p) measured with spICPMS agreed with that measured by counting particles deposited on filters, and calculated from the mass concentration of the analyte.
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