Session Index

Nonlinear fluorescence microscopy methods, including two-photon and three-photon microscopic methods, have become increasingly popular in biomedical researches. Due to highly selective excitation of fluorophores, nonlinear light microscopes enjoy a much-improved imaging depth than single photon fluorescence microscopes. With the help of low-repetition femtosecond lasers, some groups have achieved greater than 1 mm penetration depths in mouse brain. We are investigating the potential of combining nonlinear light excitation with focal modulation in attempt to further reduce the strong background and bring the penetration depth to 2 mm and above. We have been focusing on design issues of spatiotemporal phase modulator, a key component for additional background rejection. Various designs have been evaluated and optimized to achieve the best combination of modulation depth, background modulation, as well as spatial resolution.

 

In the decades since the invention of multiphoton microscopy, this imaging modality continues to make significant impact in diverse fields of biology and medicine. In my lab, we have been developing nonlinear optical imaging to address basic physiological questions and seeking medical applications. The fields we have investigated include dermatology, ophthalmology, hepatology, tissue engineering, infectious diseases, and others. We have found that imaging tissue and organs at a large scale and in three dimensions can provide a wealth of structural and functional information absent in two-dimensional microscopy. Relevant to connectome and cancer biology, it has become increasing clear that developing technology that can achieve high content tissue cytometric information in three-dimensions can lead to unprecedented understanding of biology and personalized medicine. I will present results describing our efforts in these two directions.

 

In nonlinear optical imaging of biological specimens, more than half of the generated luminescence signal is lost, when signal collection is performed in the epi-illuminated geometry. Properly designed coated cover glass can enhance detected signal in multiphoton microscopy and result in improved image quality

 

Traditional histological procedures, which require staining of tissues, reveal pathological hallmarks of Alzheimer’s disease viz. senile plaques and neurofibrillary tangles (NFT). In a label-free approach, we have shown here that second and third harmonic generation simultaneously can provide contrast of senile plaques; while NFT only shows second harmonic generation contrast.

 

Recent studies have indicated that the physical property of lipid bilayers may greatly alter the function of membrane proteins. We investigated the effects of dissolved air gases on the mechanical properties and stability of lipid membranes using DCM. We found that nitrogen significantly increased the bending rigidity of lipid membranes.