Developing label-free optical contrast for biomedical imaging

Fri, Aug 20, 2010, 12:00 pm to 6:00 pm
Joseph Henry Room
Host: Thomas Gregor
Speaker: Dan Fu The George R. Harrison Spectroscopy Laboratory Massachusetts Institute of Technology Abstract: Modern microscopy has long been the driving force in tackling biological and biomedical problems. Key innovations in new microscopy technologies are focused on three different aspects: resolution, contrast and speed. Fluorescence microscopy is the most commonly used technique due to its high contrast. However, there are often cases where fluorescence is not applicable or complicates the problem being studied. In this talk, I will present developments of novel label-free imaging techniques that do not rely on fluorescence. Representative applications to biological and biomedical problems will also be discussed. The first development I will describe is quantitative phase microscopy. Quantitative phase microscopy visualizes the quantitative morphology of the cell in 2D and 3D with nm depth sensitivity at ms time scale. It also provides important parameters such as the drymass of the cell. Dynamic motion of cells is studied using high speed imaging. The second development is focused on new nonlinear optical contrasts such as two photon absorption and stimulated Raman. Two photon absorption of hemoglobin has been used to visualize blood vessel architecture and oxygenation level in live animals, which can be a useful technique in monitoring angiogenesis and hypoxia with appropriate tumor model system. Two photon absorption imaging of melanin offers a new opportunity in studying the progress of melanoma development. Stimulated Raman microscopy provides direct chemical contrast at high spatial resolution and fast speed.