Quantum dot emission

Fig. 9.21 In vivo images of MWCNTs-QDs (0.5 tg ml-1 in PBS) in mice injected at different body regions a) MWCNTs attached with CdSe/Zns quantum dots (emission of 600 nm) at middorsal location b) MWCNTs attached with CdSe/ZnS quantum dots at ventrolateral locations, the suspensions were diluted by PBS at various concentrations as indicated (A through E) c) MWCNTs attached with InGaP/ZnS quantum dots (emission of 680 nm, 0.25 jj,g ml-1 in PBS) in liver, kidney, and leg muscles. All images were taken successfully in 2 min under epi-UV illuminator with excitation of 435nm. (Shi et al. 2007). Published with permission from Wiley-VCH see Color Plates)...

Properties (1) and (2), combined with the fact that quantum dot emission spectra are characteristically narrow and symmetrical compared to those of conventional fluorochromes, offer considerable potential for clean, multiple fluorescence labeling of specimens. With appropriate emission filters in place, the same excitation wavelengths can be used to produce fluorescence from carefully selected quantum dots of different sizes, resulting in the emission of closely spaced, but nonoverlapping colors. 

TABLE 7.4 Quantum Dot Emission Wavelength as a Function of Nanocrystal Composition and Size... 

Artemyev MV, Woggon U, Wannemacher R, Jaschinski H, Langbein W (2001) Light trapped in a photonic dot microspheres act as a cavity for quantum dot emission. Nano Lett 1 309... 

Micic O I ef a/1996 Highly efficient band-edge emission from InP quantum dots Appi. Phys. Lett. 68 3150... 

Relaxation Dynamics of Non-Emissive State for Water-Soluble CdTe Quantum Dots 147 8.4... 

Non-Emissive Relaxation Dynamics in CdTe Quantum dots... 

Figure 8.11a shows steady-state absorption spectra of the CdTe quantum dots in water. Each spectrum in the figure exhibits a distinct peak at a different band corresponding to its size, indicating that all of these suspensions include mono-dispersed nanocrystals. This mono-dispersibility is also supported by their emission spectra with different peak bands corresponding to particle size, as in Figure 8.11b. 

Figure 8.11 Absorption (a) and emission (b) spectra for the water-soluble CdTe quantum dots examined. The sizes for the CdTe dots are indicated in the figures.

Silica particles have been exploited in virtually every assay or detection strategy that polymer particles have been used in for bioapplication purposes. Recently, fluorescent dye-doped silica nanoparticles have been developed by a number of groups that have similar fluorescence characteristics to quantum dot nanocrystals (Chapter 9, Section 10). Fluorescent silica nanoparticles can be synthesized less expensively than quantum dots due to the fact that the silica particles incorporate standard organic dyes (Ow et al., 2005 Wang et al., 2006) and are not dependent on making reproducible populations of semiconductor particles with precise diameters to tune emission wavelengths. 

Gryczynski I, Malicka J, Jiang W, Fischer H, Chan WCW, Gryczynski Z, Grudzinski W, Lakowicz JR (2005) Surface-plasmon-coupled emission of quantum dots. J Phys Chem B 109 1088-1093... 

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