Estimation for diameter of superparamagnetic particles in resting eggs.

Ferromagnetic resonance (FMR) with an electron spin resonance (ESR) apparatus was investigated for super-paramagnetic particles within resting eggs. High-field (HF) resonance lines near g=2 resulted from single superparamagnetic particles, were detected from ESR spectra of resting eggs. The size of isolated superparamagnetic particles within 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 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, , with that were raised, did not show FMR spectra, showing no magnetic particles within resting eggs. Therefore, it suggested that superparamagnetic particles within resting eggs, were mineralized in as the result of biomineralization of Fe originated from .