Raman reporter molecule

Schlilcker, S. et al. (2011). Design and synthesis of Raman reporter molecules for tissue imaging by immuno-SERS microscopy. Journal of Biophotonics, 4(6) 453-463. doi 10.1002/jbio.201000116. 

Figure 11.9 illustrates a representative system of SERS-based immunoassays. Rohr et al. first proposed an SERS-based immunoassay using dye-labeled antibodies and silver-island films coated with a capture antibody [60]. In their system, a silver-island film is used for the base substrate linked to the capture antibody as well as the SERS-active substrate that enhances Raman signals of reporter molecules when the reporter dye-linked antibody conjugate is bound to the captured... 

The same group has also reported a multiplexed assay based upon the Mirkin approach but in this case using an array format with non-fluorescent Raman reporters and the reporter molecule was added directly to the surface of the... 

Recent work has been published on the use of SERS reporters for in vivo analysis. In 2008, Shuming Nie published work on the in vivo targeting of tumors in live mice [65]. The SERRS particles consisted of 60 nm gold nanoparticles functionalized with a Raman reporter dye molecule and then stabilized with thiolated polyethylene glycols (PEGs). Targeted SERS nanoparticles were prepared by having a mixed monolayer of thiolated PEG and a heterofunctional thiolated PEG with a carboxylic... 

In Chapter 10, Samnel Hemandez-Rivera and cowoikers show that Raman detection of trace amoimts of explosives and other hazardous materials on surfaces can be improved by ten to one thousand times with the addition of colloidal metallic nanoparticles to contaminated areas. Banahalli Ratna and colleagues demonstrate that orgarrized spatial distribution of fluorescent reporter molecules on a virus capsid eliminates the commonly encountered problem of fluorescence quenching. Using such viral nanoparticles, they show in Chapter 11 that enhanced fluorescence for the detection of protein toxins is possible. 

SERS biosensors have also been used in conjunction with reporter molecules which have strong, distinct Raman spectra as labels. Some such molecules are thiophenol (TP), 2-naphthalenethiol (NT) [39], 5,5-dithiobis(succinimidyl-2-nitro-benzoate) (DSNB, a derivative of dithiobis (benzoic add)) [40], (4-mercaptobenzoic acid, 4MBA) [41], etc. Because the Raman signal is usually quite weak, high-power lasers are required to elicit a measurable signal. However, it is not easy to miniaturize such lasers. Hence, enhancement of the signal by surface modification (ie, SERS) and/or using reporter molecules makes this technique more amenable to use in POC scenarios. 

As reporter molecules to be attached to these nanoaggregates we chose dyes known and approved in biological and medical applications as fluorescence markers. However, instead of using the broad and relatively non-specific fluorescence signals of these dyes, here we rely on their specific (surface enhanced) Raman signature. 

Raman signals (h Vas) of the attached reporter molecules as well as of different cellular molecules (see also Figure 5). 

For most purposes only the Stokes-shifted Raman spectmm, which results from molecules in the ground electronic and vibrational states being excited, is measured and reported. Anti-Stokes spectra arise from molecules in vibrational excited states returning to the ground state. The relative intensities of the Stokes and anti-Stokes bands are proportional to the relative populations of the ground and excited vibrational states. These proportions are temperature-dependent and foUow a Boltzmann distribution. At room temperature, the anti-Stokes Stokes intensity ratio decreases by a factor of 10 with each 480 cm from the exciting frequency. Because of the weakness of the anti-Stokes spectmm (except at low frequency shift), the most important use of this spectmm is for optical temperature measurement (qv) using the Boltzmann distribution function. 

Polarized Raman and infrared spectra of orthorhombic Ss at low temperatures were reported by Gautier and Debeau (30-50 K) [106] and by Becucci et al. (< 20 K) [107]. Since natural sulfur is composed of isotopomers of the Ss molecules (see below), the vibrational spectra of isotopically pure a- Ss ( S purity >99.95%) as well as of natural sulfur have been investigated in... 

Infrared spectra of gaseous [30, 31], condensed [32] and matrix-isolated S2O have been measured [33], and Raman spectra of the matrix-isolated molecule were reported [15]. In Table 2 the infrared absorption bands of 5 iso-topomers of S2O are listed some bands coincide with other absorptions. 

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