title: Synchrotron infrared spectromicroscopy as a novel bioanalytical microprobe for individual living cells: cytotoxicity considerations.
abstract: Synchrotron radiation-based Fourier transform infrared spectromicroscopy is a newly emerging analytical tool capable of monitoring the biochemistry within an individual living mammalian cell in real time. This unique technique provides infrared (IR) spectra, hence chemical information, with high signal to noise at spatial resolutions as fine as 3-10 microm. Mid-IR photons are too low in energy (0.05-0.5 eV) to either break bonds or to cause ionization, and the synchrotron IR beam has been shown to produce minimal sample heating. However, an important question remains, "Does the intense synchrotron beam induce any cytotoxic effects in living cells?" In this work, we present the results from a series of standard biological assays to evaluate any short- and/or long-term effects on cells exposed to the synchrotron radiation-based infrared (SR-IR) beam. Cell viability was tested using alcian blue dye exclusion and colony formation assays. Cell-cycle progression was tested with bromodeoxyuridine (BrdU) uptake during DNA synthesis. Cell metabolism was tested using a 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay. All control, 5, 10, and 20 min SR-IR exposure tests (267 total and over 1000 controls) show no evidence of cytotoxic effects. Concurrent infrared spectra obtained with each experiment confirm no detectable biochemical changes between control and exposed cells.
authors.affiliation: Lawrence Berkeley National Lab, Center for Environmental Biotechnology, Mail stop 70A-3317, Berkeley, California 94720, USA. hyholman@lbl.gov
authors.forename: Hoi-Ying N
authors.initials: HY
authors.lastname: Holman
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Bjornstad
authors.forename: Morgan P
authors.initials: MP
authors.lastname: McNamara
authors.forename: Michael C
authors.initials: MC
authors.lastname: Martin
authors.forename: Wayne R
authors.initials: WR
authors.lastname: McKinney
authors.forename: Eleanor A
authors.initials: EA
authors.lastname: Blakely
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001973:Bromodeoxyuridine / Q000378:metabolism; D002453:Cell Cycle / Q000528:radiation effects; D002455:Cell Division / Q000528:radiation effects; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D004247:DNA / Q000096:biosynthesis; D006801:Humans; D007259:Infrared Rays / Q000009:adverse effects; D008853:Microscopy / Q000379:methods*; D009243:NAD / Q000378:metabolism; D055095:Optics and Photonics; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D017356:Synchrotrons; D013778:Tetrazolium Salts; D013844:Thiazoles
chemical_list: D013778:Tetrazolium Salts; D013844:Thiazoles; D009243:NAD; D000255:Adenosine Triphosphate; D004247:DNA; C022616:thiazolyl blue; D001973:Bromodeoxyuridine
keywords: Non-programmatic