Study of the Stability of a Paramagnetic Label Linked to Mesoporous Silica Surface in Contact with Rat Mesothelial Cells in Culture

• Published in: Environmental health perspectives 1997-09, Vol.105 (suppl 5), p.1031-1036
• Main Authors: Mollo, Laura, Levresse, Valerie, Ottaviani, Maria F., Ellouk-Achard, Sophie, Jaurand, Marie-Claude, Fubini, Bice
• Format: Article
• Language: English
• Subjects: Animals; Cell culture techniques; Cell lines; Cell membranes; Cells, Cultured; Cultured cells; Electron paramagnetic resonance; Electron Spin Resonance Spectroscopy; Environmental health; Epithelial Cells - metabolism; Epithelium - chemistry; Epithelium - metabolism; Line spectra; Materials; Micelles; Particle Size; Physical and Chemical Properties of Particles/Mechanisms of Toxicity; Pleura - cytology; Pleura - metabolism; Proteins - chemistry; Rats; Silicon Dioxide - chemistry; Spectroscopic analysis; Spin Labels; Surface Properties
• ISSN: 0091-6765; 1552-9924
• DOI: 10.1289/ehp.97105s51031

Stable radicals detectable by electron paramagnetic resonance (EPR) may be of use in the investigation of early events in cell-particle toxicity. Piperidine-N-oxyl derivatives (nitroxides), covalently linked to the surface of a high surface area silica (used as model solid for the technique), served as probes in the investigation of the effects of incubation of silica particles with mesothelial cells. A mesoporous silica (MCM-41), prepared by precipitation from a micellar solution, was the most appropriate silica-based particle for this purpose, as its channels allow direct contact with small molecules but not with macromolecules. The cytotoxicity of this amorphous silica is very low, allowing relatively high particle loading in the cell cultures. Both the high surface area of the sample and the large amount of inorganic material extracted from the cell culture provide enough material to run reasonably intense EPR spectra. Computer-aided analysis of the EPR spectra of silica-bound nitroxides provided information on the sensitivity of the labeled silica monitoring different environments, e.g., to follow the path of particles in a mammalian cell culture. Upon contact of the particles with mesothelial cells, the mean distance among the labels at the silica surface decreased as a consequence of the release of oxidizing and/or radical moieties from the cells.