Multiplexing Detection Schemes

Current security and health concerns require robust, cost-effective, and efficient tools and strategies for the simultaneous analysis, detection, and often even quantification of multiple analytes or events in parallel. The ability to screen for and quantify multiple targets in a single assay or measurement is termed multiplexing. 

Spectral multiplexing or multicolor detection is typically performed at a single excitation wavelength, and relies on the discrimination between different fluorescent labels by their emission wavelength. Desirable optical properties of suitable fluoro-phores are a tunable Stokes shift and very narrow, preferably well-separated emission bands of simple shape. 

The suitability of organic dyes for multicolor signaling at single wavelength excitation is limited due to their optical properties (Fig. Id, f and Table 1). With 

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Common to all narrow-bandwidth excitation schemes is sequential scanning of an experimental parameter in order to adjust the Raman shift in CRS detection. In order to obtain an entire CRS spectrum, this is not only time consuming but also prone to sources of noise induced by fluctuations in laser pulse parameters. As a consequence, dynamical changes in a CRS spectrum are difficult to follow. This problem can be circumvented by use of multiplex CRS spectroscopies [48, 49], which will be discussed in combination with CARS and SRS microscopy in Sects. 6.3 and 6.4, respectively. 

Fig. 7.3 Au NP-on-wiie SERS sensor for multiplexed pathogen DNA detection, a Scheme of the target DNA detection, b Scheme of multiplex approach for detection of DNA extracted from four bacteria, c SERS intensities of the RRM when sample contains different kinds of target DNA. A Efm Enterococcus faecium B Sau Staphylococcus aureus, C Smal Stenotrophomorms maltophilia, D Vvul Vibrio vulnificus (adapted with permission from Kang et al. 2010. Copyright 2010 American Chemical Society)...

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