Universitą degli studi di Pavia
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Study of endogenous fluorophores to caracterize the functional morphology of biological tissues.
Optical biopsy is a diagnostic approach exploiting the photophysical phenomena arising from the interaction of ultraviolet-visible-near infrared radiations with matter to provide real-time information on the morpho-functional properties of a biological substrate, in the absence of sample removal.
Among the photophysical phenomena, considerable attention is paid to autofluorescence or light-induced fluorescence, which is the fluorescence arising from a biological substrate upon excitation at a suitable wavelength, in the absence of exogenous markers, because of the presence of endogenous biomolecules acting as fluorophores. The endogenous fluorophores may be involved both in cell metabolic processes (for instance, pyridine coenzymes, flavins and lipofuscins) and in tissue histological organization (for instance, collagen and elastin). Because emission properties – such as amplitude and spectral shape – depend on the nature, amount, physico-chemical state, intratissue distribution and microenvironment of fluorescing molecules, in close relationship with the morphological and metabolic conditions of the biological substrate, autofluorescence represents an intrinsic tissue diagnostic parameter. The occurrence of either physiological changes or pathological conditions gives rise to alterations of the tissue morpho-functional state, resulting in changes of autofluorescence emission properties suitable for diagnostic purposes, provided that both endogenous fluorophores' photophysical characteristics and tissue optical properties are defined.
At least two major advantages emerge in the characterization of biological substrates through autofluorescence analysis: the widespread occurrence of endogenous fluorophores, allowing an extension of its application to various bio-medical fields, and the technological progress as to excitation sources, light delivery and detection system of fluorescence signals, allowing the high sensitivity of the fluorometric techniques to be fully exploited.
In bulk tissues, autofluorescence analysis is widely considered for in vivo diagnostic purposes for both the detection of pathologies and the monitoring of organ functionality under normal, physiologically or purposely altered conditions.
As to pathologies, optical biopsy diagnostic applications concern mainly the neoplastic growth. The occurrence of a neoplasia alters the autofluorescence properties, acting on multiple factors, such as biochemical composition, histological organization and optical properties of the tissue. The optical properties, in particular, can affect the propagation of both excitation and emission light, thus influencing the amplitude and the spectral shape of the signal collected by the measuring probe, depending on the presence of non-fluorescent absorbers and scatterers within the tissue.
Optical biopsy is a diagnostic approach exploiting the photophysical phenomena arising from the interaction of ultraviolet-visible-near infrared radiations with matter to provide real-time information on the morpho-functional properties of a biological substrate, in the absence of sample removal.
Among the photophysical phenomena, considerable attention is paid to autofluorescence or light-induced fluorescence, which is the fluorescence arising from a biological substrate upon excitation at a suitable wavelength, in the absence of exogenous markers, because of the presence of endogenous biomolecules acting as fluorophores. The endogenous fluorophores may be involved both in cell metabolic processes (for instance, pyridine coenzymes, flavins and lipofuscins) and in tissue histological organization (for instance, collagen and elastin). Because emission properties – such as amplitude and spectral shape – depend on the nature, amount, physico-chemical state, intratissue distribution and microenvironment of fluorescing molecules, in close relationship with the morphological and metabolic conditions of the biological substrate, autofluorescence represents an intrinsic tissue diagnostic parameter. The occurrence of either physiological changes or pathological conditions gives rise to alterations of the tissue morpho-functional state, resulting in changes of autofluorescence emission properties suitable for diagnostic purposes, provided that both endogenous fluorophores' photophysical characteristics and tissue optical properties are defined.
At least two major advantages emerge in the characterization of biological substrates through autofluorescence analysis: the widespread occurrence of endogenous fluorophores, allowing an extension of its application to various bio-medical fields, and the technological progress as to excitation sources, light delivery and detection system of fluorescence signals, allowing the high sensitivity of the fluorometric techniques to be fully exploited.
In bulk tissues, autofluorescence analysis is widely considered for in vivo diagnostic purposes for both the detection of pathologies and the monitoring of organ functionality under normal, physiologically or purposely altered conditions.
As to pathologies, optical biopsy diagnostic applications concern mainly the neoplastic growth. The occurrence of a neoplasia alters the autofluorescence properties, acting on multiple factors, such as biochemical composition, histological organization and optical properties of the tissue. The optical properties, in particular, can affect the propagation of both excitation and emission light, thus influencing the amplitude and the spectral shape of the signal collected by the measuring probe, depending on the presence of non-fluorescent absorbers and scatterers within the tissue.
