title: Size-dependent toxicity of silica nano-particles to Chlorella kessleri.
abstract: SiO(2) nano-particles were found to exhibit size-dependent toxicity toward the alga, Chlorella kessleri. Small SiO(2) nano-particles exhibit stronger toxicity: 50% inhibitory concentrations (IC(50)) value for 5 nm = 0.8 +/- 0.6%, 26 nm = 7.1 +/- 2.8%, and 78 nm = 9.1 +/- 4.7%. Enlargement of the cell body was observed by flow cytometry, which is due to the presence of structures that obstructed cell division. Optical and transmission microscopes were used to observe coagulated cells with incomplete division. Although the physiological effect of SiO(2) nano-particles was not clear, SiO(2) nano-particles are toxic, at least for algae in aquatic media. Under the transmission electron microscope, several amorphous structures appeared in the cells that were exposed to 5-nm silica nano-particles.
authors.affiliation: School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Tokyo, Japan. kfujiwa@ls.toyaku.ac.jp
authors.forename: Kitao
authors.initials: K
authors.lastname: Fujiwara
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Suematsu
authors.forename: Emiko
authors.initials: E
authors.lastname: Kiyomiya
authors.forename: Motohide
authors.initials: M
authors.lastname: Aoki
authors.forename: Mamiko
authors.initials: M
authors.lastname: Sato
authors.forename: Nobuko
authors.initials: N
authors.lastname: Moritoki
mesh_terms: D002708:Chlorella / Q000166:cytology / Q000187:drug effects* / Q000648:ultrastructure; D005434:Flow Cytometry; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D010316:Particle Size; D012822:Silicon Dioxide / Q000737:chemistry / Q000633:toxicity*
chemical_list: D012822:Silicon Dioxide