Availability Investigation Of Porphyrins Fluorescence Based Method For Cancer Identification

The effective cancer identification and diagnosis has taken on a considerably increased importance in saving cancer patients' lives, especially in the early stage. Among the various diagnosis techniques developed so far, few are effective to detect the, cancer in the early stage. More and more attention has been paid to fluorescence spectroscopy for its advantages of real time detection, impersonality, innocuity and so on. Although the cancer identification using spectroscopy has been studied extensively, it is still at primary stage, so that further analysis and demonstration is necessary. Porphyrins are a kind of important products of metabolism that will be influenced by cancer, hence become target molecules in spectral investigation. In this thesis, fluorescence spectroscopy is used to investigate the availability of cancer identification based on porphyrins fluorescence.The thesis begins with an introduction of some basic concepts about fluorescence-based cancer diagnosis, relevant theory basis and apparatus used in the investigations. The bulk of author's contribution, within the general group effort, was to perform the experiments which are described in Chapters 2 to 5 and form the main part of thesis.In chapter 2, chicken embryos are taken as the model of cell proliferation in order to investigate the change of porphyrins metabolism as tumors develop. It turns out that the level of PpIX metabolism rises in the early stage and then drops gradually in the late stage. At the same time, it is found that the fluorescence isn't emitted only by PpIX itself, but it also influenced by proteins and other porphyrins.In order to realize tumor identification, the spectral investigation to gastric tissues has been carried out and is described in chapter 3. From the spectral analysis of 68 samples from 34 gastric cancer patients, it is found that gastric tumors emit stronger red fluorescence than normal tissues, while the outcome in the blue-green region is opposite. If the fluorescence in the two regions is combined for consideration, more obvious result can be acquired to make the identification of cancer tissues possible.Availability Investigation of Porphyrins Fluorescence Based Method for Cancer IdentificationFurthermore, in chapter 4, fluorescence spectra of the whole blood were analyzed to investigate the availability of cancer identification based on metabolism in body liquids. The similar results to the gastric tissues are found, which may be valuable in early cancer identification.The effort has also been made to set up a non-invasive system for fluorescence detection out body, which is presented in chapter 5. But it shows that the system should be improved much in order to realized its satisfactory function in practice.Finally, Chapter 6 contains a general discussion of the work and suggests possible future developments.To sum up, it is available to identify cancer based on porphyrins fluorescence, although there are still practical problems to be solved and improved.