title: Cd2+ Toxicity to a green alga Chlamydomonas reinhardtii as influenced by its adsorption on TiO2 engineered nanoparticles.
abstract: In the present study, Cd(2+) adsorption on polyacrylate-coated TiO(2) engineered nanoparticles (TiO(2)-ENs) and its effect on the bioavailability as well as toxicity of Cd(2+) to a green alga Chlamydomonas reinhardtii were investigated. TiO(2)-ENs could be well dispersed in the experimental medium and their pH(pzc) is approximately 2. There was a quick adsorption of Cd(2+) on TiO(2)-ENs and a steady state was reached within 30 min. A pseudo-first order kinetics was found for the time-related changes in the amount of Cd(2+) complexed with TiO(2)-ENs. At equilibrium, Cd(2+) adsorption followed the Langmuir isotherm with the maximum binding capacity 31.9, 177.1, and 242.2 mg/g when the TiO(2)-EN concentration was 1, 10, and 100 mg/l, respectively. On the other hand, Cd(2+) toxicity was alleviated in the presence of TiO(2)-ENs. Algal growth was less suppressed in treatments with comparable total Cd(2+) concentration but more TiO(2)-ENs. However, such toxicity difference disappeared and all the data points could be fitted to a single Logistic dose-response curve when cell growth inhibition was plotted against the free Cd(2+) concentration. No detectable amount of TiO(2)-ENs was found to be associated with the algal cells. Therefore, TiO(2)-ENs could reduce the free Cd(2+) concentration in the toxicity media, which further lowered its bioavailability and toxicity to C. reinhardtii.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu Province, China.
authors.forename: Wei-Wan
authors.initials: WW
authors.lastname: Yang
authors.forename: Ai-Jun
authors.initials: AJ
authors.lastname: Miao
authors.forename: Liu-Yan
authors.initials: LY
authors.lastname: Yang
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000327:Adsorption; D001682:Biological Availability; D002104:Cadmium / Q000737:chemistry* / Q000493:pharmacokinetics / Q000633:toxicity*; D016825:Chlamydomonas reinhardtii / Q000187:drug effects* / Q000378:metabolism; D004738:Engineering; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology; D014025:Titanium / Q000737:chemistry*
chemical_list: D000180:Acrylic Resins; D002104:Cadmium; C009495:titanium dioxide; C006903:carbopol 940; D014025:Titanium