title: Development of a polydimethylsiloxane film-based passive dosing method in the in vitro DR-CALUX® assay.
abstract: In bioassays, exposure concentrations of test compounds are usually expressed as nominal concentrations. As a result of various processes, such as adsorption, degradation, or uptake, the actual freely dissolved concentration of the test compound may differ from the nominal concentration. The goal of the present study was to develop a method to dose passively the freely dissolved fraction of organic chemicals in an in vitro bioassay with adherent cells. To this end, a polydimethylsiloxane (PDMS) film-based method was developed for a reporter gene assay for dioxin-like compounds in a rat liver cell line. Polydimethylsiloxane films loaded with test compounds ensure that the concentration during exposure is in equilibrium and that the ratio between the concentration on the film and the concentration in medium is constant. Benzo[k]fluoranthene (BkF) was used as a model compound to develop the passive dosing method in transwell plates, which was further tested with a complex mixture, i.e., an extract prepared from a contaminated sediment. A higher dioxin-like activity was found when extracts were dosed by passive dosing with PDMS than when directly added to medium. Comparison with analysis of the concentration of BkF in medium shows that passive dosing of individual chemicals may not be necessary if freely dissolved concentrations are known. Use of PDMS for passive dosing of complex samples may represent a more realistic method for exposure in in vitro bioassays.
authors.affiliation: Institute for Environmental Studies, VU University Amsterdam, Amsterdam, The Netherlands. petra.booij@ivm.vu.nl
authors.forename: Petra
authors.initials: P
authors.lastname: Booij
authors.forename: Marja H
authors.initials: MH
authors.lastname: Lamoree
authors.forename: Pim E G
authors.initials: PE
authors.lastname: Leonards
authors.forename: Peter H
authors.initials: PH
authors.lastname: Cenijn
authors.forename: Hans J C
authors.initials: HJ
authors.lastname: Klamer
authors.forename: L Alexander
authors.initials: LA
authors.lastname: van Vliet
authors.forename: Johan
authors.initials: J
authors.lastname: Akerman
authors.forename: Juliette
authors.initials: J
authors.lastname: Legler
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000379:methods*; D002460:Cell Line; D005591:Chemical Fractionation; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D005449:Fluorenes / Q000737:chemistry / Q000633:toxicity*; D019015:Geologic Sediments / Q000737:chemistry; D007700:Kinetics; D051381:Rats; D018675:Toxicity Tests / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity*
chemical_list: D004129:Dimethylpolysiloxanes; D005449:Fluorenes; D014874:Water Pollutants, Chemical; C013830:baysilon; C022921:benzo(k)fluoranthene