Second Harmonic Generation Microscopic Imaging And Its Application In Prostate Tissues

Microscopic imaging based on second-harmonic generation (SHG) has beenproving to be a powerful tool for biomedical studies, especailly in cancer research.SHG imaging brings no photobleaching and toxicity. It's a promising tool forhigh-resolution, three-dimensional studies biology tissues. Now, many experimentsand explanations about SHG in biological tissues have been reported, owing to thecomplexity and variety of biological tissuses, the mechanism of SHG in biologicaltissues is not clear all the same.In this paper, on theory of SHG, we set up a model for SHG imaging study oncollagen like tissues at a molecular level. Because of this model, it is possible toquantitatively investigation SHG when we change the length, size or the number ofmolecules. Then polarization modulated of SHG was also made by us on our model.Experiments on second-harmonic signals in nuclei from prostate hyperplasia andcancer tissues in the mouse model(C57BL6) have been demonstrated for the firsttime. Results show that there is a difference on the relation of SHG intensity and thesize of the nuclei. Statistical analyses (t test) of total 405 measurements (204 nucleifrom BPH and 201 nuclei from PC) show that SHG signals from BPH and PC have adistinct difference (p＜0.05), providing a strong evidence of a potential opticalmethod for a early prostate malignancy diagnosis based on SHG signals. Excitatedsamples with different wavelength laser a wavelength sensitivity was also observed.