title: Effect of PpIX photoproducts formation on pO2measurement by time-resolved delayed fluorescence spectroscopy of PpIX in solution and in vivo.
abstract: The measurement of Protoporphyrin IX delayed fluorescence lifetime is a minimally invasive method for monitoring the levels of oxygen in cells and tissues. The excitation of Protoporphyrin IX during this measurement can lead to the formation of photoproducts in vitro and in vivo. The influence of their luminescence on the measured Protoporphyrin IX delayed fluorescence lifetimes was studied in solution and in vivo on the Chick's chorioallantoic membrane (CAM) model under various oxygen enriched air conditions (0mmHg, 37mmHg and 155mmHg). The presence of photoproducts disturbs such measurements since the delayed fluorescence emission of some of them spectrally overlaps with that of Protoporphyrin IX. One possible way to avoid this obstacle is to detect Protoporphyrin IX's delayed fluorescence lifetime in a very specific spectral range (620-640nm). Another possibility is to excite Protoporphyrin IX with light doses much lower than 10J/cm2, quite possibly as low as a fraction 1J/cm2at 405nm. This leads to an increased accuracy of pO2detection. Furthermore, this method allows combination of diagnosis and therapy in one step. This helps to improve detection systems and real-time identification of tissue respiration, which is tuned for the detection of PpIX luminescence and not its photoproducts.
authors.affiliation: Center for Interdisciplinary Biosciences, Faculty of Science, P.J. Safarik University, Jesenna 5, Kosice 041 54, Slovak Republic; Laboratory of Organometallic and Medicinal Chemistry, Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology in Lausanne (EPFL), Station 6, Batiment de Chimie, CH-1015 Lausanne, Switzerland. Electronic address: veronika.huntosova@upjs.sk.
authors.forename: Veronika
authors.initials: V
authors.lastname: Huntosova
authors.affiliation: Laboratory of Organometallic and Medicinal Chemistry, Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology in Lausanne (EPFL), Station 6, Batiment de Chimie, CH-1015 Lausanne, Switzerland. Electronic address: emmanuel.gerelli@epfl.ch.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Gerelli
authors.affiliation: Laboratory of Organometallic and Medicinal Chemistry, Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology in Lausanne (EPFL), Station 6, Batiment de Chimie, CH-1015 Lausanne, Switzerland. Electronic address: matthieu.zellweger@epfl.ch.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Zellweger
authors.affiliation: Laboratory of Organometallic and Medicinal Chemistry, Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology in Lausanne (EPFL), Station 6, Batiment de Chimie, CH-1015 Lausanne, Switzerland. Electronic address: georges.wagnieres@epfl.ch.
authors.forename: Georges
authors.initials: G
authors.lastname: Wagnières
mesh_terms: D000818:Animals; D002642:Chick Embryo; D010100:Oxygen / Q000032:analysis*; D011524:Protoporphyrins / Q000032:analysis*; D012996:Solutions; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D011524:Protoporphyrins; D012996:Solutions; C028025:protoporphyrin IX; D010100:Oxygen
keywords: Delayed fluorescence; In vivo; Oxygenation; Photoproduct; Protoporphyrin IX