Lifetimes multiplexing

Grabolle M, Kapusta P, Nann T, Shu X, Ziegler J, Resch-Genger U (2009) Fluorescence lifetime multiplexing with nanocrystals and organic labels. Anal Chem 81 7807-7813... 

This comparison of the spectroscopic properties of the different types of fluorescent reporters underlines that semiconductor QDs and upconverting nanoparticles have no analogs in the field of organic dyes. Therefore, their unique features are unrivaled. The different molecular labels detailed here each display unique advantages that can compete with some of the favorable features of QDs and upconverting phosphors such as long lifetimes in the case of MLC systems and lanthanide chelates or very narrow emission bands for lanthanide chelates beneficial for spectral multiplexing. 

Snyder TM, McGown LB (2005) Multiplex single strand conformation polymorphism analysis by capillary electrophoresis with on-the-fly fluorescence lifetime detection. Appl Spectrosc 59 335-339... 

In this section we will review the application of near-IR system instrumentation to the most commonly encountered fluorescence measurements such as steady-state spectra, excited state lifetimes, anisotropy, microscopy, multiplexing, high-performance liquid chromatography (HPLC), and sensors. 

Farrens and Song<40) have replaced the original spark source with a picosecond diode laser in a multiplexed dual wavelength T-formatfluorometer.(41)With an overall instrumental response width of ca. 300 psec full-width half-maximum (FWHM), near-IR fluorescence lifetimes as low as 75 psec in the case of l,l -diethyl-4,4 carbo-cyanine iodide (DCI) (excitation 660 nm) and decay components as low as 48 psec in the case of 124 kDa oat phytochrome (excitation 752 nm) were reported. 

The potential for using multiplexed single-photon counting to acquire fluorescence lifetime data from a distributed array of optical fiber sensors, each sensing a different analyte, has recently been demonstrated by Birch etal.(39,47) Figure 12.9 illustrates such a network to be used in conjunction with the arrangement shown in Figure 12.6. 

Birch et al. have used the Philips XP2254B, an S20 version of the XP2020Q, to study the fluorescence lifetimes of a series of aminotetraphenylporphyrins in a multiplexed fluorometer. 83 The extended red response (S20R) version of this device, the XP2257B, has been used with IR spark source excitation to study the fluorescence lifetimes of carbocyanine dyes up to 930 nm emission in isotropic and anisotropic media. 55,561 % 84) An improved voltage divider network has been developed for linear focused photomultipliers which reduces thermionic noise from the photocathode by an order of magnitude by restricting the collection of photoelectrons to the center of the photocathode. 84 ... 

Problems still remain in overcoming the intrinsic optical cross-talk in arrays of avalanche photodiodes, which at present precludes equivalent applications to multianode MCP-PMs in such as multiplexed lifetime measurements at different fluorescence wavelengths. 

In addition, the luminescence lifetime of quantum dots is approximately one order of magnitude longer than that of their organic counterparts.30 Thus, the autofluorescence of biological samples can effectively be filtered, for example, with time-gated measurements, in the case of these inorganic luminophores. Moreover, QDs are also particularly interesting for multiplexed analysis because of two of their inherent... 

These devices have proved their capability to actually achieve the theoretical multiplex (SNR) advantage. This makes them very attractive for studies of light phenomena that have ultra-short (/ sec to psec) lifetimes or that involve measurements of very low SNR. 

Multiplexed multidetector systems can also be used in laser scanning microscopy to obtain lifetime images in several emission wavelength intervals and for different excitation wavelength. Please see Sect. 5.7, page 129 and Sect. 5.6, page 121. 

High selectivity due to efficient wavelength discrimination (excitation and emission), which can be further enhanced by lifetime discrimination potential for multiplexing. 

Interconnections consist of multiplexers and nets. Initially, nets are used to interconnect functional units and registers as indicated in the original specification (the data-flow graph). Multiplexers are used for nets with more than one source. Path analysis and lifetime information are also used to generate the correct interconnection. 

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