title: Microfluorometric detection of catecholamines with multiphoton-excited fluorescence.
abstract: We demonstrate sensitive spatially resolved detection of physiological chromophores that emit in the ultraviolet (<330 nm). An atypical laser source (a visible wavelength femtosecond optical parametric oscillator), and an unconventional collection geometry (a lensless detector that detects the forward-emitted fluorescence) enable this detection. We report the excitation spectra of the catecholamines dopamine and norepinephrine, together with near-UV emitters serotonin and tryptophan, in the range of 550-595 nm. We estimate the molecular two-photon action cross section of dopamine, norepinephrine, and serotonin to be 1.2 mGM (1 GM, or Goppert Mayor, is equal to 10(-58) m4 s(-1) photon(-1)), 2 mGM, and 43 mGM, respectively, at 560 nm. The sensitivity achieved by this method holds promise for the microscopic imaging of vesicular catecholamines in live cells.
authors.affiliation: Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba Mumbai 400005, India.
authors.forename: J
authors.initials: J
authors.lastname: Balaji
authors.forename: Chandra S
authors.initials: CS
authors.lastname: Reddy
authors.forename: S K
authors.initials: SK
authors.lastname: Kaushalya
authors.forename: Sudipta
authors.initials: S
authors.lastname: Maiti
mesh_terms: D002395:Catecholamines / Q000032:analysis*; D004298:Dopamine / Q000032:analysis; D004837:Epinephrine / Q000032:analysis; D005453:Fluorescence; D005470:Fluorometry; D017785:Photons; D012680:Sensitivity and Specificity; D012701:Serotonin / Q000032:analysis; D014364:Tryptophan / Q000032:analysis
chemical_list: D002395:Catecholamines; D012701:Serotonin; D014364:Tryptophan; D004298:Dopamine; D004837:Epinephrine