Research On Visible Light-Induced Blood Fluorescence Spectra

Based on the experimental researches on the fluorescence spectra of whole blood, erythrocyte and hemoglobin excited by visible LED light and Ar+ laser with various wavelengths, the relationship of LED light and Ar+ laser excited blood cells fluorescence spectra with the concentration is investigated theoretically and experimentally, and the fluorescence spectra induced by LED light and Ar+ laser are compared.LED light-induced fluorescence spectra of whole blood, erythrocyte and hemoglobin are obtained in the case of different concentration of blood cells solution with various excitation wavelengths. The intensity and peaks of the spectra from 430nm to 700nm depend strongly on the concentration of blood cells. Based on the theoretical analysis and experimental researches, it is presented that the wider spectra are resulted from the many fluorophores with large numbers of vibrational energy levels on the ground level in the blood cells, and the reduction of the spectral intensity is due to the reabsorption of the blood cells and the energy transfer of the collisions between the fluorophore and another one or other macromolecule. On the other hand, when the concentration of the blood cells is increased, the reabsorption of the blood cells, the secondary fluorescence due to the reabsorption and the influence of the concentration on the energy levels of fluorophores are all the factors of the red-shifted spectral peaks.The fluorescence spectra of whole blood and erythrocyte under various wavelengths and power Ar+ lasers excitation are shown that they are very similar in richer and sharper peaks. However, the intensity of the hemoglobin fluorescence spectra is lower and their structures are quite different. The mechanisms of laser-induced blood fluorescence spectra and the spectra deriving from the fluorophores on the erythrocyte membrane are presented. On the other hand, the lower intensity of the hemoglobin fluorescence spectra is due to the fluorescence quenching from resonance energy transfer between the fluorophores in hemoglobin with ambient.Comparisons of LED and laser induced blood fluorescence spectra indicate that the latter can show partly fine structure of blood cells. The absorption of the fluorophores to the wavelength of exciting light has definite selectivity, which depend on energy level structure and state of the fluorophores.The research consequences may offer a theoretical and experimental reference to know the conformation characteristic and the rule of biomolecular change and process clinic treatment or diagnose technology in virtue of endogenous or extrinsic luminescence characteristic.