Intrinsic photosensitizer fluorescence measured using multi-diameter single-fiber spectroscopy in vivo.
Quantification of fluorescence in vivo is complicated by the influence of tissue optical properties on the collected fluorescence signal. When tissue optical properties in the measurement volume are quantified, one can obtain the intrinsic fluorescence, which equals the product of fluorophore absorption coefficient and quantum yield. We applied this method to in vivo single-fiber fluorescence spectroscopy measurements on mouse tongue, skin, liver, and oral squamous cell carcinoma, where we detected intrinsic fluorescence spectra of the photosensitizers chlorin e6 and Bremachlorin at t=[3,4.5,6,24,48]  h incubation time. We observed a tissue-dependent maximum of 35% variation in the total correction factor over the visible wavelength range. Significant differences in spectral shape over time between sensitizers were observed. Although the wavelength position of the fluorescence intensity maximum for ce6 shifted to the red, Bremachlorin showed a blue shift. Furthermore, the Bremachlorin peak appeared to be broader than the ce6 fluorescence peak. Intrinsic fluorescence intensity, which can be related to photosensitizer concentration, was decreasing for all time points but showed significantly more Bremachlorin present compared to ce6 at long incubation times. Results from this study can be used to define an optimal treatment protocol for Bremachlorin-based photodynamic therapy.
Postgraduate School Molecular Medicine, Center for Optical Diagnostics and Therapy, Department of Radiation Oncology, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
Floor
F
van Leeuwen-van Zaane
Postgraduate School Molecular Medicine, Center for Optical Diagnostics and Therapy, Department of Radiation Oncology, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
Ute A
UA
Gamm
Leiden University Medical Centre, Department of Radiology, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
Pieter B A A
PB
van Driel
Leiden University Medical Centre, Department of Radiology, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
Thomas J
TJ
Snoeks
Center for Optical Diagnostics and Therapy, Department of Otolaryngology-Head and Neck Surgery, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
Henriette S
HS
de Bruijn
Center for Optical Diagnostics and Therapy, Department of Otolaryngology-Head and Neck Surgery, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
Angelique
A
van der Ploeg-van den Heuvel
Postgraduate School Molecular Medicine, Center for Optical Diagnostics and Therapy, Department of Radiation Oncology, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
Henricus J C M
HJ
Sterenborg
Leiden University Medical Centre, Department of Radiology, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
Clemens W
CW
Löwik
Postgraduate School Molecular Medicine, Center for Optical Diagnostics and Therapy, Department of Radiation Oncology, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
Arjen
A
Amelink
Center for Optical Diagnostics and Therapy, Department of Otolaryngology-Head and Neck Surgery, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
Dominic J
DJ
Robinson
D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000473:pathology; D002734:Chlorophyll / Q000031:analogs & derivatives* / Q000737:chemistry; D002735:Chlorophyllides; D005260:Female; D005453:Fluorescence; D049452:Green Fluorescent Proteins; D008099:Liver / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008856:Microscopy, Fluorescence; D009062:Mouth Neoplasms / Q000473:pathology; D016011:Normal Distribution; D055095:Optics and Photonics; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry; D012867:Skin / Q000473:pathology; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D014059:Tongue / Q000473:pathology
D002735:Chlorophyllides; D017319:Photosensitizing Agents; D011166:Porphyrins; D002734:Chlorophyll; D049452:Green Fluorescent Proteins; C062985:phytochlorin