Ekaterina Borisova, Aleksandra Zhelyazkova, Tsanislava Genova, Latchezar Avramov, Institute of Electronics, Bulgarian Academy of Sciences, Bulgaria
1) Institute of Electronics, Bulgarian Academy of Sciences, 72, Tsarigradsko chaussee Blvd., 1784 Sofia, Bulgaria, e-mail: firstname.lastname@example.org
Petranka Troyanova, Elmira Pavlova, Ivan Terziev, Nikolay Penkov
2) University hospital “Queen Jiovanna-ISUL”, 8 Bialo more str., 1527 Sofia, Bulgaria
Steady-state fluorescence spectroscopy is a powerful tool for investigation of complex and multicomponent fluorescent samples, including human tissues. It is one of the most prominent and widely – used tool for investigation of the spectral properties, as well as a tool for differentiation of the pathologies based on spectral discrimination. Autofluorescence is a non-invasive and real-time technique that could found clinical application for initial diagnosis and monitoring of the therapy of human neoplasia.
However, the disadvantages related to application of autofluorescence spectroscopy into clinical practice are related to the low level of the detected signals, which require special technical solutions, and to the complexity of the signal detected, which require complex data analysis. The last one is related to the overlapped spectra of excitation and of emission for different endogenous fluorophores, which all could have diagnostic meaning. Synchronous fluorescence spectroscopy (SFS), which is a specific mode of a steady-state fluorescence technique, could be used to solve this problem.
Analysis of the fluorescence through the SFS method is performed by maintaining constant wavelength interval between excitation wavelength and emission wavelength through the spectrum. This allows optimal excitation of the emission maxima, which result in narrower emission peaks. That is the main reason for the greater sensitivity of SFS in comparison with standard fluorescence detection. Narrower peaks in the obtained fluorescence spectra allows decrease the extent of spectral overlaps and this effect is useful in investigating multi-component samples which consist mixture of fluorescence compounds, like biological tissues.
Our study presents SFS results ex vivo over pairs of healthy and cancerous cutaneous tissues. The procedure of obtaining the investigated samples includes their excision during surgery for removal of neoplasia lesions. After the surgical removal biological samples are transported in isothermal conditions and safe-keeping solution from the hospital to the spectral laboratory, where their SFS is investigated. All patients received and signed written informed consent and this research is approved by Ethics committee of the hospital.
SFS measurements were performed with excitation wavelength in the spectral range of 280-440 nm with increment of 10 nm and wavelength interval (offset) in the range of 10-200 nm with increment of 10 nm. Improved spectral resolution of the emission was obtained and better differentiation of the endogenous fluorophores and their alterations in the process of tumour development were observed. Optimal SFS signals of discrimination between normal and cancerous tissues would be also discussed.
Acknowledgements: This work is supported in part by the National Science Fund of Bulgarian Ministry of Education and Science under grant #DFNI-B02/9/2014 “Development of biophotonics methods as a basis of oncology theranostics”, and under COST Action BM1205 “European Network for Skin Cancer Detection using Laser Imaging”.
Dr. Ekaterina Georgieva Borisova
Institute of Electronics, Bulgarian Academy of Sciences, Associate Professor
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