Imaging biological

For the application of QDs to three-dimensional biological imaging, a large two-photon absorption cross section is required to avoid cell damage by light irradiation. For application to optoelectronics, QDs should have a large nonlinear refractive index as well as fast response. Two-photon absorption and the optical Kerr effect of QDs are third-order nonlinear optical effects, which can be evaluated from the third-order nonlinear susceptibility, or the nonlinear refractive index, y, and the nonlinear absorption coefficient, p. Experimentally, third-order nonlinear optical parameters have been examined by four-wave mixing and Z-scan experiments. 

Noise can be also introduced by biochemical heterogeneity of the specimen. This can be a major cause of uncertainty in biological imaging. The high (three-dimensional) spatial resolution of fluorescence microscopy results in low numbers of fluorophores in the detection volume. In a typical biological sample, the number of fluorophores in the detection volume can be as low as 2-3 fluorophores for a confocal microscope equipped with a high NA objective at a fluorescent dye concentration of 100 nM. This introduces another source of noise for imaging applications, chemical or molecular noise, related to the inherent randomness of diffusion and the interaction of molecules. 

Han W, Mou J, Sheng J, Yang J, Shao Z. Cryo atomic force microscopy A new approach for biological imaging at high resolution. Biochemistry 1995 34 8215-8220. 

Jaiswal JK, Simon SM (2004) Potentials and pitfalls of fluorescent quantum dots for biological imaging. Trends Cell Biol 14 497-504... 

Wu C, Bull B, Christensen K, McNeill J (2009) Ratiometric single-nanoparticle oxygen sensors for biological imaging. Angew Chem Int Ed 48 2741-2745... 

Makarava N, Parfenov A, Baskakov IV (2005) Water-soluble hybrid nanoclusters with extra bright and photostable emissions a new tool for biological imaging. Biophys J 89 572-580... 

This chapter introduces principles of three nonlinear contrast mechanisms— MPF, SHG, and THG—for microscopic imaging. The instrumentation of nonlinear multicontrast microscopy is described, and the methods of multicontrast image analysis are presented. The later parts of the chapter focus on several examples of multicontrast nonlinear microscopy applications in biological imaging. 

Lee, E. S., Lee, J. Y., and Yoo, Y. S. 2007. Nonlinear optical interference of two successive coherent anti-Stokes Raman scattering signals for biological imaging applications. J. Biomed. Opt. 12 024010. 

One of the most common trends in the recent development of nonlinear optical spectroscopies for biological imaging is the multimodal approach, which incorporates several spectroscopic techniques in one instrument. This approach allows the employment of several contrast mechanisms, such as fluorescence, second harmonic, and third harmonic (Cisek et al., Chapter 4), significantly increasing the informational content of microscopic imaging. 

Using the broadband laser pulse generated through continuum generation and an optical pulse shaper, Vacano and Motzkus (Chapter 7) and Bantus et al. (Chapter 8) demonstrate the substantial untapped potential of this approach for microscopic biological imaging and biochemical analysis. 

To capture the infrared energy, low band gap or NIR-absorbing organic columnar mesophase LC semiconductors are urgently needed for PVCs. NIR materials have potential applications for telecommunications, thermal imaging, and biological imaging. 

Case Study 6 Biological Imaging Involving Multiple Length Scales... 

Light microscopy (confocal, multiphoton), X-ray microscopy, and electron microscopy are the mainstays of imaging instrumentation for biological imaging. 

Better resolving power (at or near atomic resolution) is needed in biological imaging instruments. Imaging of discrete chemical environments in living systems remains out of reach. 

Zhao, Y Zheng, Q Dakin, K Xu, K., Martinez, M.L. and Li, W.-H.D (2004) New caged coumarin fluorophores with extraordinary uncaging cross sections suitable for biological imaging applications. Journal of the American Chemical Society, 126, 4653—4663. 

Jain PK, Lee KS, El-Sayed I, El-Sayed MA. Calculated absorption and scattering properties of gold nanoparticles of different size, shape and composition Application in biological imaging and biomedicine. J Phys Chem B 2006 110 7238-48. 

LMIG filled with bismuth (or gold) has been developed for SIMS (especially employed in ToF-SIMS) measurements. This primary ion source provides cluster beams of Bi with n = 1-7 which allow higher secondary ion yields compared to gallium or indium LMIGs ° and is well suited for special applications (biological imaging). Bismuth cluster ion beams have much better... 

J. Vasilevskis etal, US Patent 6,288,224 (September 11, 2001) Nycomed Saluter, Inc. and University of Iowa Research Foundation Biological Imaging Agent... 

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