Deep Imaging of Biological Tissue by Ultra-Efficient Photon Collection

Abstract

1722-Pos Board B614 Deep Imaging of Biological Tissue by Ultra-Efficient Photon Collection Viera Crosignani, Alexander Dvornikov, Enrico Gratton. Univesity of California, Irvine, Irvine, CA, USA. We present an upright two-photon fluorescence microscope that is capable of imaging in turbid media up to 3mm depth with micron resolution. The system utilizes a high power Ti:Sa Mai Tai laser with a group velocity dispersion com- pensator (DeepSee) for two-photon fluorescence excitation. The especially de- signed fluorescence detector, which is a key feature of the system, is capable of collecting fluorescence photons from the wide surface area (25mm diameter) of the specimen. This novel detection scheme has proven to be extremely efficient in the collection of fluorescence photons scattered by turbid media and allows about 6 fold increase in imaging depth when compared with conventional two- photon microscopes. The system is also equipped with a second fluorescence detector that allows its use as a conventional two-photon microscope and the comparison of the data acquired by both detection methods. In addition, the presented microscope is coupled to the FLIMbox (ISS, Inc.) and it has in depth FLIM imaging capabilities. The detection scheme captures fluorescence light in a transmission configuration, which was proven extremely efficient for the de- tection of SHG signals, due to their intrinsically forward propagating nature. We are also presenting in depth imaging experiments of tissue phantoms and in vivo and ex vivo biological tissue, including murine colon, small intestine, xenograft tumors, and skin vasculature. This work was supported by National Institutes of Health grants: P41- RRO3155,P50-GM076516