Detection of epithelial structure and biochemistry based on time-resolved confocal autofluorescence

A combined depth- and time-resolved fluorescence measurement system with ultraviolet excitation at 375 nm is built to assess the layered structure and biochemistry of epithelial tissue. The experiments on epithelial cells suggested that the time-resolved autofluorescence dominated by free/bound NADH signals, are sensitive indicators for cell metabolism and can be used to sense the metabolic status of epithelial tissue. Moreover, we found that the fluorescence time decays of different epithelial tissue layers can produce the contrast to resolve the tissue fine structure. This study demonstrated that the combined depth- and time-resolved autofluorescence measurements with single excitation at 375 nm can potentially provide accurate information for the diagnosis of tissue pathology.