title: Arrhenius parameter determination as a function of heating method and cellular microenvironment based on spatial cell viability analysis.
abstract: OBJECTIVE
  Predictions of injury in response to photothermal therapy in vivo are frequently made using Arrhenius parameters obtained from cell monolayers exposed to laser or water bath heating. However, the impact of different heating methods and cellular microenvironments on Arrhenius predictions has not been thoroughly investigated. This study determined the influence of heating method (water bath and laser irradiation) and cellular microenvironment (cell monolayers and tissue phantoms) on Arrhenius parameters and spatial viability.
  
  
  METHODS
  MDA-MB-231 cells seeded in monolayers and sodium alginate phantoms were heated with a water bath for 3-20 min at 46, 50, and 54 °C or laser irradiated (wavelength of 1064 nm and fluences of 40 W/cm(2) or 3.8 W/cm(2) for 0-4 min) in combination with photoabsorptive carbon nanohorns. Spatial viability was measured using digital image analysis of cells stained with calcein AM and propidium iodide and used to determine Arrhenius parameters. The influence of microenvironment and heating method on Arrhenius parameters and capability of parameters derived from more simplistic experimental conditions (e.g. water bath heating of monolayers) to predict more physiologically relevant systems (e.g. laser heating of phantoms) were assessed.
  
  
  RESULTS
  Arrhenius predictions of the treated area (<1% viable) under-predicted the measured areas in photothermally treated phantoms by 23 mm(2) using water bath treated cell monolayer parameters, 26 mm(2) using water bath treated phantom parameters, 27 mm(2) using photothermally treated monolayer parameters, and 0.7 mm(2) using photothermally treated phantom parameters.
  
  
  CONCLUSIONS
  Heating method and cellular microenvironment influenced Arrhenius parameters, with heating method having the greater impact.
authors.affiliation: Department of Mechanical Engineering, Virginia Tech, Stanger Street, Blacksburg, VA 24061, USA. jonwhit@vt.edu
authors.forename: Jon
authors.initials: J
authors.lastname: Whitney
authors.forename: William
authors.initials: W
authors.lastname: Carswell
authors.forename: Nichole
authors.initials: N
authors.lastname: Rylander
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival; D060833:Cellular Microenvironment; D006358:Hot Temperature; D006801:Humans; D006979:Hyperthermia, Induced / Q000009:adverse effects / Q000379:methods*; D007834:Lasers; D008954:Models, Biological; D012984:Software; D014867:Water
chemical_list: D014867:Water