Fluorescence ratio imaging microscopy

Various optical detection methods have been used to measure pH in vivo. Fluorescence ratio imaging microscopy using an inverted microscope was used to determine intracellular pH in tumor cells [5], NMR spectroscopy was used to continuously monitor temperature-induced pH changes in fish to study the role of intracellular pH in the maintenance of protein function [27], Additionally, NMR spectroscopy was used to map in-vivo extracellular pH in rat brain gliomas [3], Electron spin resonance (ESR), which is operated at a lower resonance, has been adapted for in-vivo pH measurements because it provides a sufficient RF penetration for deep body organs [28], The non-destructive determination of tissue pH using near-infrared diffuse reflectance spectroscopy (NIRS) has been employed for pH measurements in the muscle during... 

Martin, G. R. Jain, R. K. Noninvasive measurement of interstital pH profiles in normal and neoplastic tissue using fluorescence ratio imaging microscopy. Cancer Res. 1994, 54,... 

Undesired effects in fluorescence confocal microscopy can be corrected by ratio imaging. Rati-oing (i.e., the compensation of two channels by digital division) can substantially reduce cross-talk effects in double detectors [63]. Environmental markers indicating the pH value or the level of free calcium ions (Ca"" ) also require ratio imaging to compensate for structural densities or section thickness [19]. 

Fig. 9.8 (a) Contact angle, (b) swelling ratio, and (c) eiastic moduius of the poiymer Aims after 0, 15, and 90 min of UV exposure. The inset images in (b) are confocai microscopy images of the films (xz-plane), where gels are equilibrated in a fluorescent dye containing PBS solution to obtain contrast. (Reproduced from [65] with permission from The Royal Society of Chemistry)... 

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