title: The molecular structure of complexes formed by chromium or cobalt ions in simulated physiological fluids.
abstract: It is well recognized that workers in mines and manufacturers of hard metals in contact with metal ions have increased risk of cancer. However, the various chemical forms of these ions in living organisms are not well characterized, and little is known of how they interact with biological environments. Here, we sought to elucidate the molecular structures formed by cobalt (Co) and chromium (Cr) ions in simulated biological fluids. Transmission electron microscopy observations revealed that Cr(III) formed nanoscale complexes which precipitate in both RPMI 1640 and DMEM high glucose media. However, no complexes were observed with Co(II) and Cr(VI). Energy-dispersive X-ray analysis, elemental analysis, and Fourier transform infrared (FT-IR) spectroscopy indicated that Cr(III) ions act as chelating entities between PO(4) groups, amino acids, and calcium. Although the exact nature of the bonds remains to be investigated, the presence of PO(4) may favor the formation of low energy hydrogen bonds. Interestingly, the nature of amino acids varied in Cr(III) complexes formed in RPMI 1640 compared to those formed in DMEM high glucose. The absence of sulphur in the elemental analysis spectrum suggested that methionine and cystine, two amino acids containing sulphur, are not involved in the formation of Cr(III) complexes. Thus, the lower toxicity of Cr(III) compared to Co(II) and Cr(VI) may be related to the formation of these chemical complexes. These results may bring some insight in understanding the relationship between toxicity and the chelating capabilities of various metal ions in vitro and in vivo.
authors.affiliation: Department of Biomedical Engineering, McGill University, Duff Medical Building, 3775 University Street, Montreal, Quebec H3A 2B4, Canada.
authors.forename: Cathy
authors.initials: C
authors.lastname: Tkaczyk
authors.forename: Olga L
authors.initials: OL
authors.lastname: Huk
authors.forename: Fackson
authors.initials: F
authors.lastname: Mwale
authors.forename: John
authors.initials: J
authors.lastname: Antoniou
authors.forename: David J
authors.initials: DJ
authors.lastname: Zukor
authors.forename: Alain
authors.initials: A
authors.lastname: Petit
authors.forename: Maryam
authors.initials: M
authors.lastname: Tabrizian
mesh_terms: D001826:Body Fluids / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D003470:Culture Media; D004602:Elements; D007477:Ions / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D003470:Culture Media; D004602:Elements; D007477:Ions; D002857:Chromium; D003035:Cobalt