This method was successfully utilized for the determination of Hg( II) in environmental samples. (2,2,6,6-Tetramethylpiperidin-1-yl)oxy (TEMPO), used as reference for EPR calibration. Protein radical scavenging may contribute to. 5 Bruker Biospin, 15 Fortune Dr., Billerica, Massachusetts 01821. 3 Estimates for 13C direct observe experiments can be made in a similar fashion: on our 500 MHz spectrometers, 2 mol of material can be observed in a few hours. TEMPO protects cells from photosensitized death at attainable plasma concentrations. Electron paramagnetic resonance (EPR) spectroscopy can be applied to directly. Micromolar TEMPO concentrations prevent oxidation of cell proteins in macrophages. TEMPO nitroxide scavenges tyrosyl and tryptophanyl radicals with k 10 7 10 8 M 1 s 1. The emission intensity increases linearly in the concentration range of 1 × 10 −7 to 5 × 10 −13 M Hg( II) and the detection limit was found to be 0.75 fM L −1 Hg( II) ( S/ N = 3). Highlights Protein radicals are formed during cellular metabolism and in human disease. We are a developer, manufacturer and distributor of high-performance scientific instruments and analytical and diagnostic solutions that enable our. Further, the DAT-AuNPs showed an extreme selectivity towards the determination of 10 nM Hg( II) in the presence of a 50 000-fold higher concentration of common interferents. Based on the enhancement of emission intensity, the concentration of Hg( II) was determined. This suggests that Hg( II) induced the fluorescence properties of DAT-AuNPs due to photoinduced electron transfer and metal binding-induced conformational restriction upon complexation. The spin labeling efficiency was more than 75.
#BRUKER EPR STANDARDS TEMPO MICROMOLAR FREE#
The quantum yield estimated for DAT-AuNPs in the presence of Hg( II) was 1.5-fold higher than that of free DAT-AuNPs. Complexin I at high micromolar concentrations inhibited trans-SNARE. The DAT-AuNPs show the emission maximum at 776 nm while exciting at 520 nm and the emission intensity was enhanced after the addition of even nanomolar Hg( II). The XPS of Hg5p shows two peaks at 69.3 eV for 5p1 and 74.35 eV for 5p3, suggesting that mercury was present as Hg( II), coordinated with DAT-AuNPs. (4mm and 5mm OD are the ONLY sizes for cryogenic experiments) b.) EPR tubes are made out of quartz whereas NMR tubes are made out of. The binding of Hg( II) with DAT-AuNPs was confirmed by XPS. a.) Standard EPR tube size 4mm OD, however, sizes do vary (2mm, 3mm, 5mm, 10mm) and can be accommodated by the instrument. The HR-TEM images show that the spherical structure of DAT-AuNPs was changed into a chain-like structure after the addition of micromolar Hg( II) due to the strong coordination of DAT-AuNPs with Hg( II).
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3,5-Diamino-1,2,4-triazole capped gold nanoparticles (DAT-AuNPs) were synthesized by a wet chemical method. In this paper, we report the morphological changes of gold nanoparticles induced by micromolar Hg( II) and the determination of femtomolar Hg( II) by a luminescent method.