Nonlinear optical microscopy and spectroscopy by pulse shaping of a coherent fiber supercontinuum

Nonlinear optical microscopy and spectroscopy enable three-dimensional sub-µm-resolution imaging with deeper penetration and reduced photodamage, and have been established as powerful methods in biomedicine. The most appealing aspect of nonlinear optical imaging is the wealth of molecular contrast derived from various multiphoton processes. Two-photon and three-photon fluorescence microscopy visualizes endogenous fluorophores. Second and third harmonic generation microscopy maps optical non-centrosymmetry and heterogeneity. Coherent Raman scattering spectroscopic imaging probes intrinsic molecular vibrations. An integrated platform with combined modalities realizes label-free imaging of diverse biomolecules, and is highly desirable for biomedical fields. However, bringing these techniques together is not trivial due to the complexity of laser and imaging systems, and the requirements of modalities need to be met and often compromised. These limitations have hindered the biological application and clinical translation of the technology. In this thesis, multimodal nonlinear optical imaging by pulse shaping of a coherent fiber supercontinuum is demonstrated and applied to breast cancer research. The supercontinuum is generated in an all-normal-dispersion fiber, achieving a spectrum spanning the optical biological window with high coherence and high power. Efficient two-photon and three-photon fluorescence microscopy, second and third harmonic generation microscopy, as well as coherent anti-Stoke Raman scattering spectroscopic imaging are performed by adaptive pulse shaping of the supercontinuum pulses. Different molecules and structures in normal and cancerous human breast tissues are visualized, and the complimentary multiphoton signals and the vibrational spectrum form a complete molecular profile for analyzing the biochemical composition in situ. Using this approach, mammary tumor development in a carcinogen-induced rat model is investigated in a 9-week longitudinal study. Multiphoton molecular biomarkers and their transformation, such as regulated cellularity, collagen organization, elastin organization, angiogenesis, lipid degradation, and distribution of microvesicles are identified and correlated by multimodal imaging. The proposed technology presents simplicity and applicability, and may have a broader impact in biomedical research and fundamental science.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Bioengineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Liu, Yuan

Contributors dc:contributor

• Boppart, Stephen A.
• Gruebele, Martin
• Toussaint, Kimani C.
• Myong, Su-A

• breast cancer
• coherent fiber supercontinuum
• pulse shaping
• nonlinear optical spectroscopy
• Nonlinear optical microscopy

Statement dc:rights

• Copyright 2015 Yuan Liu

Handle dc:identifier

http://hdl.handle.net/2142/78700

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/78700