On fluorescence intensity

Fixler, D., Namer, Y., Yishay, Y. and Deutsch, M. (2006). Influence of fluorescence anisotropy on fluorescence intensity and lifetime measurement theory, simulations and experiments. IEEE Trans. Biomed. Eng. 53, 1141-52. 

Lakowicz JR, Shen Y, D Auria S, Malicka J, Fang J, Gryczynski Z, Gryczynski I (2002) Radiative decay engineering 2. Effects of silver island films on fluorescence intensity, lifetimes, and resonance energy transfer. Anal Biochem 301 261-277... 

Immunoassays based on phase-modulation spectroscopy have been implemented by two distinctly different approaches. Phase-resolved immunoassays rely on fluorescence intensity measurements, in which the emission of one fluorescent species in a mixture is suppressed, and the remainder is quantitated. Phase fluorescence immunoassays utilize measurements of the phase angle and modulation, which change in response to fluorescence lifetime changes. Common aspects of the theory and instrumentation are discussed in this section, followed by individual discussions of the different approaches. 

Fig. 6. Schematic diagram of the steps involved in the cookie cutter method of cell selection. (A) Cells are grown on plastic Petri dishes covered with a darkened nylon film. (B) Based on fluorescence intensity image scans using a stage-scanning laser microscope, rare event cells are identified, and octagonal welds are made around those cells to fuse the film to the dish. (C) The film is then peeled away from the dish. (D) The cookies containing the desired cells remain on the dish so that the cells may be analyzed further or subsequently cloned.

KMS Sundaram, I Curry. Fluorometric determination of aminocarb and mexacarbate and some of their metabolites by liquid chromatography influence of structural factors on fluorescence intensity. J Liq Chromatogr 17 3759-3774, 1994. 

Figure 10.16 Effect of temperature on fluorescence intensity of native (A) and guanidine unfolded ( ) AEDANS-RNase. Intensities are expressed relative to that measured at 10°C for the same sample (native or unfolded). The buffer is 50 mM cacodylate, pH 6.5, in the absence or presence of 6 M guanidine hydrochloride. The protein concentration is 10 5 M. Excitation wavelength 350 nm emission wavelength 476 nm. Source Jullien, M., Garel, J-R., Merola, F. and Brochon J.-C. (1986). European Biophysical Journal, 13, 131-137, Figure No. 1. With kind permission of Springer Science and Business Media (1,2, and 3).

Describe the temperature effects on fluorescence intensity, anisotropy, and lifetime. 

Due to the use of a confocal volume, FCS is particularly suited for miniaturization in HTS and relatively insensitive to auto fluorescent test compounds. Moreover, in compound testing, the small path length of the confocal volume greatly limits any filter effects on fluorescence intensity. As in FP, the requirement for large differences in mass in the assay design is a limitation to the applicability of FCS. However, it can be overcome by methods like Fluorescence Intensity Distribution Analysis (FIDA) or two-colour cross correlation derived from the original FCS concept. 

The combination of fluorophores and suspended colloid particles could be used in metal-enhanced solution assays. Scheme 8.1 depicts the use of fluorophores and suspended colloid particles. Previous studies on fluorescence intensity enhancement between fluorophores and suspended particles in terms of metal core of nanoparticles, fluorophore type, and spacer used are summarized in Table 8.2. 

Table 8.2 Studies on fluorescent intensity b ween fluorophores and suspended colloid particles...

Table 8.3 Studies on fluorescent intensity between fluorophores and nanostructured metal surfaces or adsorbed colloidal particles...

Lakowicz, J. R., Shen, Y., D Auria, S., Malicka, J., Fang, J., Gryczynski, Z., and Gryc nski, I. (2002). Radiative Decay Engineering 2. Effects of Silver Island Films on Fluorescence Intensity, Lifetimes, and Resonance Energy Transfer. i4 a/. Biochem. 301 261-277. 

Molecular structure and environmental factors such as acidity, solvent polarity, and temperature variations exert significant influence on fluorescence intensity. Also, variations in mobile-phase composition will... 

INFLUENCE OF SOLVENT ON FLUORESCENCE INTENSITY OF ERGOTAMINE(4.5xlO 3M)2 Xex= 350 ran... 

Figure 37. The effect of increased terephthalate ion (TA) concentration on fluorescence intensity at 20 kHz.

Effect of Fe(III) on fluorescence intensity. Addition of Fe (III) to the final solution of rutin caused the fluorescence intensity to increase significantly. Varying concentrations of Fe(III) (from lxlO-7 to 0.1 mol/L) were added to the standard solution of rutin (lxlO-2 mol/L). The maximum signal for rutin was observed at iron concentration 1 x10 4 mol/L. Further increasing concentration decreased the emission intensity. Therefore, a concentration of lxlO-4 mol/L of Fe (III) was selected for subsequent experiments. 

The effect of pH, The effect of pH on fluorescence intensity of amino acids in the absence and presence of MHP was studied. It revealed the changes in fluorescence intensity of amino acids in the pH 3.5, 7.4, and 10.0 buffer solutions. The fluorescence intensity of tyrosine is stronger in acidic and neutral media. Hence, phosphate buffer solution (pH=7.4) was selected for controlling pH in the following studies. 

The effect of HP and MHP concentration on fluorescence intensity. The amino acid concentration was fixed, and the MHP concentration varied. This revealed that the fluorescence intensity of the amino acids was remarkably quenched, and the emission wavelength shifted to a shorter wavelength. It was especially remarkable to D, L- (or L-) tryptophan, but the excitation wavelength was unchanged (Fig. 1). 

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