The Study Of Some High Signal-Noise-Ratio Detecting Techniques Based Optical Bioimaging Methods

Due to their unique optical properties and advantages, gold nanorods(GNRs), upconversion nanoparticles(UCNPs) and coherent nonlinear Raman scattering(CNRS) have become the research hotspots and gained lots of attentions whithin the filed of optical biomedical imaging in the past decade. On the purpose of high contrast optical bioimaging, this dissertation detailedly studied sevral high signal noise ratio detecting techniques:GNRs as an absorption and scattering contrast agent in the applications of in vitro and phantom bioimaging, the excitation optimization of high contrast UCNPs based optical bioimaging and the improvement for label free CNRS bioimaging.Various GNRs were synthesized using a seed mediated method, and further characterizations were done. Mesoporous silica encapsulation for GNRs was realized via a single-step coating method and we studied the impact of the surfactant CTAB (Hexadecyl trimethyl ammonium Bromide) concentration on the efficiency of silica coating. Mesoporous silica-coated GNRs almost shown no cytotoxicity to human cells and could keep highly stable in acid, basic, electrolyte solution and cell medium, facilitating their more successful and wider applications in biophotonics. Antibody-conjugated mesoporous silica-coated GNRs were introduced to dark field scattering imaging of cancer cells. These GNRs with wavelength-selective LSPR bands were demonstrated as efficient optical probes for early cancer cell diagnosis applications.A block tissue phantom was prepared with GNRs inclusion and then was performed scanning diffusion imaging. The3-D reconstruction for tissue absorption coefficient was calculated. We proposed simplex GNRs structure as a multifunctional platform simultaneously for diffusion optical tomography (contrast agent) and selective phototheraml therapy(SPPT)(therapeutic agent). The temperature distribution of tumor-bearing tissue was strictly calculated and the damage fragment in the SPPT process was also predicted. Some studies of dosimetric issues were also discussed.In this dissertation, based on the fact that light around980nm suffers from an intrinsic disadvantage:water, as the most significant ingredient of animal and human body, has a huge absorption peak around980nm it was pointed out that980nm excitation would probably heat up the sample and have limited imaging depth in the process of bioimaging.We have experimentally and computationally studied the overheating effect and limited penetration depth of980-nm laser irradiation in the UCNPs based optical bioimaging.A new efficient excitation approach using915-nm laser was proposed to excite UCNPs to emit UC photoluminescence for bioimaging. Comparing with980-nm laser,915-nm laser has much lower water absorption and induced a much lower temperature rise acceptable to animal skin. Our phantom imaging experiments have demonstrated that the915-nm laser excitation method can achieve larger imaging depth range in tissue and animal imaging. Various UCNPs have been synthesized, functionalized and characterized. Antibody conjugated UCNPs and PEG coated UCNPs were synthesized using facile methods and subsequently used for targeting in vitro and in vivo bioimaging studies, respectively.Utilizing supercontinuum light output from photonic crystal fiber and femtosencond laser we successfully built coherent antistokes Raman microscopy and stimulated Raman microscopy systems. Take the advantages of coherence property of coherent Raman signal we realized Raman spectroscopy and imaging at a distance under low NA objective. Due to chirpled property of suppercontinuum we implemented broardband coherent Raman bioimaging via simply adjusting the time delay between the tow pulses. The stimulated emission optical system was also built and further studies will proceed.