title: Estimation for diameter of superparamagnetic particles inDaphniaresting eggs.
abstract: Ferromagnetic resonance (FMR) with an electron spin resonance (ESR) apparatus was investigated for super-paramagnetic particles withinDaphniaresting eggs. High-field (HF) resonance lines near g=2 resulted from single superparamagnetic particles, were detected from ESR spectra ofDaphniaresting eggs. The size of isolated superparamagnetic particles withinDaphniaresting 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 ofDaphniaresting 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 thatDaphniawere raised, did not show FMR spectra, showing no magnetic particles withinDaphniaresting eggs. Therefore, it suggested that superparamagnetic particles withinDaphniaresting eggs, were mineralized inDaphniaas the result of biomineralization of Fe originated fromChlorella.
authors.affiliation: Department of Integrative Bioscience and Biomedical Engineering, Waseda University, 2-2 Wakamatsucho, Shinjuku-ku, Tokyo 162-8480, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Sakata
authors.affiliation: Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
authors.forename: Tamami
authors.initials: T
authors.lastname: Kawasaki
authors.affiliation: Materials Characterization Central Laboratory, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
authors.forename: Toshimichi
authors.initials: T
authors.lastname: Shibue
authors.affiliation: Department of Biology, Waseda University, 2-2 Wakamatsucho, Shinjuku-ku, Tokyo 162-8480, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Namiki
keywords: Daphnia resting egg; FMR; SAXS; magnetite; superparamagnetic particle