Fluorescence imaging is the current major optical method for cell and tissue analysis. It relies on the use of fluorescent molecular probes which are either expressed by genes which have been modified, or are tagged on to molecules of interest. The modification can interfere with normal function and hamper the interpretation of experimental results. Furthermore, the fluorophores themselves are subject to photobleaching which results in limited imaging time and prevents long term studies. Coherent anti-Stokes Raman scattering (CARS) microscopy is a nonlinear optical imaging technique that allows high-speed vibrational imaging of molecules. CARS microscopy offers several unique advantages: (a) CARS imaging is label-free and non-destructive. (b) The nonlinear dependence on excitation intensity ensures that the CARS signal is only generated in the focal center, providing an inherent sub-micron 3D spatial resolution. (c) CARS imaging offers intrinsic chemical selectivity and allows bond-specific contrast. Thus CARS imaging has the potential to become a vital method for minimal invasive and quantitative monitoring of cell and tissue which is critical for biological research and medical diagnostics. The key hurdles for this enabling technology to be widely adopted by biomedical researchers are the technical and operational limitations of the existing laser systems to generate the required tunable, high-power, and short-pulsed laser beams. These systems are bulky, expensive and require regular maintenance. Agiltron, a leading portable Raman instrument producer, in collaboration with Purdue University, proposes to bring the CARS research level laboratory instrument into the market by developing a compact, robust and affordable fiber laser based CARS microscope. In Phase I we will demonstrate the feasibility of this effort by developing and prototyping several fiberoptic components that are currently not commercially available and then constructing a functional all fiberoptic CARS system. We will demonstrate chemical selective, high contrast and spatially resolution imaging of cells and tissues. In Phase II, we will address design optimization, fabrication of associated components at drastically lower cost, and performance improvement with the goal of commercializing this powerful technique. We will also design and demonstrate a miniaturized fiber CARS imaging endoscope to facilitate minimal invasive in-situ diagnostics in clinical environment. The successful implementation of the proposed research will result in robust and reliable chemical imaging microscopes and endoscopes that provide real time, quantitative and localized structural and molecular information about in-vivo and in-vitro cell and tissues.
The capability to perform non-invasive, real-time, compositional, and sub-cellular measurement of cell and tissue will greatly facilitate our understanding of obesity and related diseases, provide rapid and accurate diagnostics of atherosclerosis, and enhance the detection and diagnosis of tumor in breast, lung, colon, and throat .The all fiber microscope will also allow high-speed spectral analysis and chemical imaging of samples in pharmaceutical, environmental, and other research fields.
