title: Dispersion method for safety research on manufactured nanomaterials.
abstract: Nanomaterials tend to agglomerate in aqueous media, resulting in inaccurate safety assessment of the biological response to these substances. The present study searched for suitable dispersion methods for the preparation of nanomaterial suspensions. Titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles were dispersed in a biocompatible dispersion medium by direct probe-type sonicator and indirect cup-type sonicator. Size characterization was completed using dynamic light scattering and transmission electron microscopy. A series of dispersion time and output power, as well as two different particle concentrations were tested. Microscopic contamination of metal titanium that broke away from the tip of the probe into the suspension was found. Size of agglomerated nanoparticles decreased with increase in sonication time or output power. Particle concentration did not show obvious effect on size distribution of TiO2 nanoparticles, while significant reduction of secondary diameter of ZnO was observed at higher concentration. A practicable protocol was then adopted and sizes of well-dispersed nanoparticles increased by less than 10% at 7 d after sonication. Multi-walled carbon nanotubes were also well dispersed by the same protocol. The cup-type sonicator might be a useful alternative to the traditional bath-type sonicator or probe-type sonicator based on its effective energy delivery and assurance of suspension purity.
authors.affiliation: Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Japan.
authors.forename: Wenting
authors.initials: W
authors.lastname: Wu
authors.forename: Gaku
authors.initials: G
authors.lastname: Ichihara
authors.forename: Yuka
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Kiyora
authors.initials: K
authors.lastname: Izuoka
authors.forename: Saeko
authors.initials: S
authors.lastname: Oikawa-Tada
authors.forename: Jie
authors.initials: J
authors.lastname: Chang
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Sakai
authors.forename: Kunichi
authors.initials: K
authors.lastname: Miyazawa
authors.forename: Dale
authors.initials: D
authors.lastname: Porter
authors.forename: Vincent
authors.initials: V
authors.lastname: Castranova
authors.forename: Masami
authors.initials: M
authors.lastname: Kawaguchi
authors.forename: Sahoko
authors.initials: S
authors.lastname: Ichihara
mesh_terms: D053768:Metal Nanoparticles / Q000009:adverse effects / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D043942:Nanotubes / Q000009:adverse effects / Q000737:chemistry*; D010316:Particle Size; D013010:Sonication / Q000295:instrumentation; D013535:Suspensions; D014025:Titanium / Q000737:chemistry*; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D013535:Suspensions; C009495:titanium dioxide; D014025:Titanium; D015034:Zinc Oxide