Fluorescence dynamic range

Sawicki (13) used solid-surface fluorescence techniques extensively in the 1960 s for air pollution research. In 1967, Roth (14) reported the RTF of several pharmaceuticals adsorbed on filter paper. Schulman and Walling (15) showed that several organic compounds gave RTF when adsorbed on filter paper. Faynter et al. (16) reported the first detailed analytical data for RTF and gave limits of detection, linear dynamic ranges, and reproducibilities for the compounds. 

The data can be visualized in several formats. In a gel image, the optical density at each point is related to the fluorescence intensity false color images can be used to improve the dynamic range of visualization. We usually employ a logarithmic compression to help visualize the wide dynamic range of the data the image can be processed to saturate the most intense components, allowing observation of less intense components. 

Extremely high dynamic range and exquisite sensitivity is produced by laser-induced fluorescence of FQ-labeled proteins. The dynamic range exceeds 250,000, and the detection limit is in the high yoctomole range for FQ-labeled proteins. 

Nagai, T., Yamada, S., Tominaga, T., Ichikawa, M. and Miyawaki, A. (2004). Expanded dynamic range of fluorescent indicators for Ca2+ by circularly permuted yellow fluorescent proteins. Proc. Natl. Acad. Sci. USA 101, 10554-9. 

When compared to fluorescent proteins, fluorophores and quenchers of fluorescence (short quenchers) are small molecules with sizes varying from 1 to 10 A. They are the main building blocks for constructing small molecule FRET probes. As molecular entities, they might influence the performance of the probe to a great extent. Their fluorescent properties will determine the sensitivity and dynamic range of the sensor. The success of the probe for a specific application will depend on the selection of the right fluorophores... 

The dynamic range of the fluorescence experiment is related to a number of factors but it can be orders of magnitude. It is possible, for example, to determine quinine in water from nanomolar to millimolar concentration by direct measurement. Quinine fluorescence is familiar to most people that have noticed the blue glow of quinine tonic water in sunlight. 

Various pH sensors have been built with a fluorescent pH indicator (fluorescein, eosin Y, pyranine, 4-methylumbelliferone, SNARF, carboxy-SNAFL) immobilized at the tip of an optical fiber. The response of a pH sensor corresponds to the titration curve of the indicator, which has a sigmoidal shape with an inflection point for pH = pK , but it should be emphasized that the effective pKa value can be strongly influenced by the physical and chemical properties of the matrix in which the indicator is entrapped (or of the surface on which it is immobilized) without forgetting the dependence on temperature and ionic strength. In solution, the dynamic range is restricted to approximately two pH units, whereas it can be significantly extended (up to four units) when the indicator is immobilized in a microhetero-geneous microenvironment (e.g. a sol-gel matrix). 

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