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Estimation for diameter of superparamagnetic particles in Daphnia resting eggs

View Article: PubMed Central - PubMed

ABSTRACT

Ferromagnetic resonance (FMR) with an electron spin resonance (ESR) apparatus was investigated for super-paramagnetic particles within Daphnia resting eggs. High-field (HF) resonance lines near g=2 resulted from single superparamagnetic particles, were detected from ESR spectra of Daphnia resting eggs. The size of isolated superparamagnetic particles within Daphnia resting eggs was calculated to be approximately 13 nm in diameter by analysis of the temperature dependence of the HF line width. Small-angle X-ray scattering (SAXS) analysis of Daphnia resting eggs also showed that average size of superparamagnetic particles in diameter, equivalent to magnetite, was approximately 13 nm. The combination of FMR and SAXS measurement is very effective in estimating the size of superparamagnetic particles in biological organisms, with difficulties of preparing for samples for measurement by electron microscopy. However, Chlorella, with that Daphnia were raised, did not show FMR spectra, showing no magnetic particles within Daphnia resting eggs. Therefore, it suggested that superparamagnetic particles within Daphnia resting eggs, were mineralized in Daphnia as the result of biomineralization of Fe originated from Chlorella.

No MeSH data available.


ESR spectra on Daphnia resting eggs measured at several temperatures between 24 K and 315 K.
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f1-6_53: ESR spectra on Daphnia resting eggs measured at several temperatures between 24 K and 315 K.

Mentions: Figure 1 shows electron spin resonance (ESR) spectra of dried Daphnia resting eggs measured at several temperatures between 24 K and 315 K. Each spectrum has a few characteristic structures: (1) a resonance line detected at g = 4.3, (2) a sharp line signal at g = 2.0, and (3) a pair of narrow and broad lines overlapped with each other around g = 2. They will be called as “signal A”, “signal B”, and “signal C”, respectively, in the following discussions.


Estimation for diameter of superparamagnetic particles in Daphnia resting eggs
ESR spectra on Daphnia resting eggs measured at several temperatures between 24 K and 315 K.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC5036663&req=5

f1-6_53: ESR spectra on Daphnia resting eggs measured at several temperatures between 24 K and 315 K.
Mentions: Figure 1 shows electron spin resonance (ESR) spectra of dried Daphnia resting eggs measured at several temperatures between 24 K and 315 K. Each spectrum has a few characteristic structures: (1) a resonance line detected at g = 4.3, (2) a sharp line signal at g = 2.0, and (3) a pair of narrow and broad lines overlapped with each other around g = 2. They will be called as “signal A”, “signal B”, and “signal C”, respectively, in the following discussions.

View Article: PubMed Central - PubMed

ABSTRACT

Ferromagnetic resonance (FMR) with an electron spin resonance (ESR) apparatus was investigated for super-paramagnetic particles within Daphnia resting eggs. High-field (HF) resonance lines near g=2 resulted from single superparamagnetic particles, were detected from ESR spectra of Daphnia resting eggs. The size of isolated superparamagnetic particles within Daphnia resting eggs was calculated to be approximately 13 nm in diameter by analysis of the temperature dependence of the HF line width. Small-angle X-ray scattering (SAXS) analysis of Daphnia resting eggs also showed that average size of superparamagnetic particles in diameter, equivalent to magnetite, was approximately 13 nm. The combination of FMR and SAXS measurement is very effective in estimating the size of superparamagnetic particles in biological organisms, with difficulties of preparing for samples for measurement by electron microscopy. However, Chlorella, with that Daphnia were raised, did not show FMR spectra, showing no magnetic particles within Daphnia resting eggs. Therefore, it suggested that superparamagnetic particles within Daphnia resting eggs, were mineralized in Daphnia as the result of biomineralization of Fe originated from Chlorella.

No MeSH data available.