Magnetic Nanoparticles and Quantum Dots for Analytical Applications
Published Online: 17 DEC 2012
Copyright © 2000 John Wiley & Sons, Ltd. All rights reserved.
Encyclopedia of Analytical Chemistry
How to Cite
Quach, A., Bwambok, D. K. and Tarr, M. A. 2012. Magnetic Nanoparticles and Quantum Dots for Analytical Applications. Encyclopedia of Analytical Chemistry. .
- Published Online: 17 DEC 2012
Quantum dots (QDs) and magnetic nanoparticles (MNPs; typically 1–100 nm in dimension) have many applications in analytical methods. Quantum dots are semiconductor nanoparticles whose electronic energy levels are substantially controlled by the particle dimensions. This control comes about due to quantum confinement; that is, the size of the particle becomes small compared with the typical exciton size in the bulk material. An exciton is a hole-electron pair that has been spatially separated due to energy input. QDs have unique optical properties that make them useful as an analytical tool. These properties include broad absorbance spectra, narrow emission spectra, emission wavelength that is tunable by adjusting particle size, high quantum efficiency, and low photobleaching rates. Selectively attaching QDs to target analytes can effectively label the analyte for highly sensitive detection using optical or electrochemical methods. MNPs are commonly made of magnetite (Fe3O4) or maghemite (γ-Fe2O3). In the nanoscale range, these materials are typically superparamagnetic. The magnetic properties of these nanomaterials allow them to be manipulated by magnetic fields or detected by magnetic means. Furthermore, the relatively low toxicity of iron oxides allow for their use for in vivo applications. This review covers analytical applications of MNPs and QDs. The literature covered is mainly articles that appeared a few years before 2010 to emphasize advances contemporary to this review.