Quantum Dot Nanocrystals

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. 

Owing to their unique (tunable-electronic) properties, semiconductor (quantum dots) nanocrystals have generated considerable interest for optical DNA detection [12], Recent activity has demonstrated the utility of quantum dot nanoparticles for enhanced electrical DNA detection [33, 34, 50], Willner et al. reported on a photoelectrochemical transduction of DNA sensing events in connection with DNA cross-linked CdS nanoparticle arrays [50], The electrostatic binding of the Ru(NH3)63+ electron acceptor to the dsDNA... 

A Safer, Easier, Faster Synthesis for CdSe Quantum Dot Nanocrystals 105... 

Okamoto, K., Vyawahare, S., and Scherer, A. (2006). Surface-plasmon enhanced bright emission from CdSe quantum-dot nanocrystals. J. Opt Soc. Am. B 23, 8 1674-1678. 

Voura EB, Jaiswal JK, Mattoussi H, Simon SM. Tracking metastatic tumor cell extravasation with quantum dot nanocrystals and fluorescence emission-scanning microscopy. Nat Med 2004 10 993-998. 

Boatman EM, Lisenky GC, NordeU KJ. 2005. A safer, easier, faster synthesis for CdSe quantum dot nanocrystals. J. Chem. Ed. 82 1697-1699. 

Finally, novel multimodal imaging nanoplatforms have also been developed these consist of mimicking nanoparticles with multimodal HDLs into which gold, iron oxide, or quantum dot nanocrystals have been incorporated for computed tomography, MR, and fluorescence imaging. 

Figure 11.4 Multiantigen multiplexed sandwich immunoassay protocol based on different quantum dots nanocrystal tracers (Reproduced with permission from [40]. Copyright 2004, American Chemical Society.)...

Sibel E. D., Ridvan S., Sibel B., Deniz H., Adil D., Arzu E (2008) Quantum dot nanocrystals having guanosine imprinted nanoshell for DNA recognition. Talanta 75 890-896... 

Figure 14.4. Semiconductor quantum dot nanocrystal synthesized by condensation of cadmium and selenium ions. This is an example of a bottom-up synthetic approach to construct nanostructures. In a bottom-up approach, the precursor atoms or molecules are combined to create a larger, hierarchical structure. In this case, cadmium ions react with selenium ions to form a cluster of the inorganic semiconductor cadmium selenide. Containing just a few hundred atoms, quantum dots are typically less than 7nm In diameter.

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