Fluorescence amplification

Some examples of fluorescence amplification with the aid of hydrophilic liquids are listed m Table 23... 

Funk et al. have used a low-pressure mercury lamp without filter to liberate inorganic tin ions from thin-layer chromatographically separated organotin compounds these were then reacted with 3-hydroxyflavone to yield blue fluorescent chromatogram zones on a yellow fluorescent background [22]. Quantitative analysis was also possible here (XoK = 405 nm, Xji = 436 nm, monochromatic filter). After treatment of the chromatogram with Triton X-100 (fluorescence amplification by a factor of 5) the detection limits for various organotin compoimds were between 200 and 500 pg (calculated as tin). 

Alkaloids, e.g. cocaine, ecgonine, benzoylecgonine, ecgonine methyl ester 280 °C, 8 min or 260°C, 10-30 min Pale blue induced fluorescence (Xn > 390 nm, cut off filter), fluorescence amplification by a factor of 2 on dipping in liquid paraffin solution detection limits <10 ng. [13]... 

Xn > 390 nm, cut off filter), fluorescence amplification by a factor of 2 on dipping in liquid paraffin solution detection limits <10 ng. 

Testosterone 180°C, 20 min Induced fluorescence and fluorescence amplification by a factor of 25 by dipping the chromatogram in a solution of Triton X-100 — chloroform (1+4). 

Chehab, F.F., and Kan, Y.W. (1989) Detection of specific DNA sequences by fluorescence amplification A color complementation assay. Proc. Natl. Acad. Sci. USA 86, 9178. 

Goldys EM, Drozdowicz-Tomsia K, Xie F, Shtoyko T, Matveeva E, Gryczynski I, Gryczynski Z (2007) Fluorescence amplification by electrochemically deposited silver nanowires with fractal architecture. J Am Chem Soc 129 12117-12122... 

If distinct peaks cannot be detected with linear amplification gain, change the detector to log amplification. Larger particles, such as E. coli and zymosan, may require log fluorescence amplification gain. 

The fluorescence amplification provided by the plasmonic nanostructures has been shown to be applicable to many fluorophores. Hence fluorophores currently employed in assays would still be suitable. However, the use of low quantum yield fluorophores would lead to much larger fluorescence enhancements (i.e. 1 / Qo) and could significantly reduce unwanted background emission fi om fluorophores distal fi om the metallic surface. 

There is another interesting system that exploits the same FRET mechanism, to obtain in this case fluorescence amplification, but based on the addition of a non-bound second fluorophore. Bin Liu and Yusong Wang [127] have immobilized a DNA strand on monodispersed silica nanoparticles (1(X) nm in diameter) and then hybridized it with a fluorescein labelled complementary DNA engineered to induce in the final double strand three pairs of T-T mismatches that are specific coordination sites for mercury ions. After incubation with metal ions and thermal washing, a cationic conjugated polymer was added. This last component was selected in order... 

As already pointed out an additional radiative rate results in an increase in the total radiative decay rate. If a dye has a high quantum yield near one, the additional radiative decay rate cannot substantially increase Ae quantum yield. The more interesting case is for low quantum yield fluorophores. In this case the enhancement can be boosted to near one and thus an overall higher fluorescence amplifications is obtained. This suggests the emission from weakly fluorescent substances can be increased if they are positioned at an... 

Figure 26. Fluorescence amplification in a Ag-cluster-layer - SnNx-interlayer system (steps from 0 -nm), photo (fewer steps than scan above). See Fig. 5.26 in the color insert at the end of this volume.

---