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Proceedings Paper

Multicolor excitation two-photon microscopy: in vivo imaging of cells and tissues
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Paper Abstract

Two-photon microscopy based on endogenous fluorescence provides non-invasive imaging of living biological system. Reduced nicotinamide adenine dinucleotide (NADH), flavin adenine dinucleotide (FAD), keratin, collagen and elastin are the endogenous fluorophores widely used as the contrast agents for imaging metabolism and morphology of living cells and tissue. The fluorescence of tryptophan, a kind of essential amino acid, conveys the information on cellular protein content, structure and microenvironment. However, it can't be effectively excited by the commonly used Ti:sapphire femtosecond laser. Because each endogenous fluorophore provides limited information, it is desirable to simultaneously excite fluorescence from as many fluorophores as possible to obtain accurate biochemical and morphological information on biomedical samples. In this study, we demonstrate that the supercontinuum generation from a photonic crystal fiber (PCF) excited by an ultrafast source can be used to excite multiple endogenous nonlinear optical signals simultaneously. By employing the spectral lifetime detection capability, this technology provides a unique approach to sense the fine structure, protein distribution and cellular metabolism of cells and tissues in vivo. In particular, with application of acetic acid, a safe contrast agent used for detection cervical cancer for many years, the tryptophan signals reveal cellular morphology and even cell-cell junctions clearly. Moreover, it was found that the pH value dependent lifetime of tryptophan fluorescence could provide the qualitative information on the gradient of pH value in epithelial tissue. Finally, we will demonstrate the potential of our multi-color TPEF microscopy to investigate the early development of cancer in epithelial tissue.

Paper Details

Date Published: 26 February 2010
PDF: 8 pages
Proc. SPIE 7569, Multiphoton Microscopy in the Biomedical Sciences X, 756920 (26 February 2010); doi: 10.1117/12.841330
Show Author Affiliations
Dong Li, Hong Kong Univ. of Science and Technology (Hong Kong, China)
Wei Zheng, Hong Kong Univ. of Science and Technology (Hong Kong, China)
Jianan Y. Qu, Hong Kong Univ. of Science and Technology (Hong Kong, China)

Published in SPIE Proceedings Vol. 7569:
Multiphoton Microscopy in the Biomedical Sciences X
Ammasi Periasamy; Peter T. C. So; Karsten König, Editor(s)

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