title: The toxicity of plastic nanoparticles to green algae as influenced by surface modification, medium hardness and cellular adsorption.
abstract: To investigate processes possibly underlying accumulation and ecological effects of plastic nano-particles we have characterized their interaction with the cell wall of green algae. More specifically, we have investigated the influence of particle surface functionality and water hardness (Ca2+concentration) on particle adsorption to algae cell walls. Polystyrene nanoparticles with different functional groups (non-functionalized, -COOH and -NH2) as well as coated (starch and PEG) gold nanoparticles were applied in these studies. Depletion measurements and atomic force microscopy (AFM) showed that adsorption of neutral and positively charged plastic nanoparticles onto the cell wall of P. subcapitata was stronger than that of negatively charged plastic particles. Results indicated that binding affinity is a function of both inter-particle and particle-cell wall interactions which are in turn influenced by the medium hardness and particle concentration. Physicochemical modelling using DLVO theory was used to interpret the experimental data, using also values for interfacial surface free energies. Our study shows that material properties and medium conditions play a crucial role in the rate and state of nanoparticle bio-adsorption for green algae. The results show that the toxicity of nanoparticles can be better described and assessed by using appropriate dose metrics including material properties, complexation/agglomeration behavior and cellular attachment and adsorption. The applied methodology provides an efficient and feasible approach for evaluating potential accumulation and hazardous effects of nanoparticles to algae caused by particle interactions with the algae cell walls.
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Miljøvej, B113, 2800 Kgs. Lyngby, Denmark; Radboud University Nijmegen, Institute for Water and Wetland Research, Department of Environmental Science, P.O. Box 9010, NL-6500 GL, Nijmegen, The Netherlands. Electronic address: T.Nolte@science.ru.nl.
authors.forename: Tom M
authors.initials: TM
authors.lastname: Nolte
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Miljøvej, B113, 2800 Kgs. Lyngby, Denmark.
authors.forename: Nanna B
authors.initials: NB
authors.lastname: Hartmann
authors.affiliation: Physical Chemistry Soft Matter, Wageningen University, Stippeneng 4, NL-6708WE Wageningen, The Netherlands.
authors.forename: J Mieke
authors.initials: JM
authors.lastname: Kleijn
authors.affiliation: Danish Fundamental Metrology, Matematiktorvet 307, 2800 Kgs. Lyngby, Denmark.
authors.forename: Jørgen
authors.initials: J
authors.lastname: Garnæs
authors.affiliation: Radboud University Nijmegen, Institute for Water and Wetland Research, Department of Environmental Science, P.O. Box 9010, NL-6500 GL, Nijmegen, The Netherlands; National Institute of Public Health and the Environment RIVM, P.O. Box 1, 3720 BA, Bilthoven, The Netherlands.
authors.forename: Dik
authors.initials: D
authors.lastname: van de Meent
authors.affiliation: Radboud University Nijmegen, Institute for Water and Wetland Research, Department of Environmental Science, P.O. Box 9010, NL-6500 GL, Nijmegen, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Jan Hendriks
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Miljøvej, B113, 2800 Kgs. Lyngby, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Baun
mesh_terms: D000327:Adsorption; D002473:Cell Wall / Q000737:chemistry; D000460:Chlorophyta / Q000737:chemistry / Q000187:drug effects*; D006046:Gold / Q000737:chemistry / Q000633:toxicity*; D006244:Hardness; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D010316:Particle Size; D011137:Polystyrenes / Q000737:chemistry / Q000633:toxicity*; D013499:Surface Properties; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity*
chemical_list: D011137:Polystyrenes; D014874:Water Pollutants, Chemical; D014867:Water; D006046:Gold
keywords: Bio-adsorption; Colloidal interaction; Nanoecotoxicity; Nanoplastics; Surface functionalization