Cation-controlled aqueous dispersions of alginic-acid-wrapped multi-walled carbon nanotubes

The utilization of alginic acid (AA) as a solubilizing agent to prepare AA-wrapped multi-walled carbon nanotube (MWCNT-AA) was investigated. AA can efficiently solubilize multi-walled carbon nanotubes (MWCNT) in aqueous solution because of the unique binding mode between the MWCNTs and the amylose homologue, and the high ratio of MWCNTs to AA. The observations of transmission electron microscopy (TEM) images has suggested that the part of the hydrophobic surface of the nanotubes is naked in the aqueous phase, which is useful for preserving its intrinsic physical and chemical properties. The addition of alkaline-earth-metal, transition-metal, heavy-metal, and lanthanoid cations to the AA-wrpped nanotubes results in the precipitation of MWCNTs from aqueous solution. The results show that cycle mediated by specific cations has potential application in aqueous biological systems and medicinal chemistry.