Quantum dots sensing

Costa-Fernandez, J. M. Pereiro, R. and Sanz-Medel, A. (2006). The use of luminescent quantum dots for optical sensing. Trends in Anal. Chem., 25,207-218. 

Murphy, C. J. (2002). Optical Sensing with Quantum Dots. Anal Chem., 74, 520A-526A. 

Particularly attractive for numerous bioanalytical applications are colloidal metal (e.g., gold) and semiconductor quantum dot nanoparticles. The conductivity and catalytic properties of such systems have been employed for developing electrochemical gas sensors, electrochemical sensors based on molecular- or polymer-functionalized nanoparticle sensing interfaces, and for the construction of different biosensors including enzyme-based electrodes, immunosensors, and DNA sensors. Advances in the application of molecular and biomolecular functionalized metal, semiconductor, and magnetic particles for electroanalytical and bio-electroanalytical applications have been reviewed by Katz et al. [142]. 

Discrete energy levels are to be observed for position (a) as well as for position (b) at exactly the same values, in case (b) somewhat better expressed than in (a). The level spacing is 135 mV. This spectrum clearly identifies the Au55 cluster as a quantum dot in the classical sense, having discrete electronic energy levels, though broader than in an atom, but nevertheless existent. The description of such quantum dots as artificial, big atoms seems indeed to be justified. 

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... 

Abstract Silver clusters, composed of only a few silver atoms, have remarkable optical properties based on electronic transitions between quantized energy levels. They have large absorption coefficients and fluorescence quantum yields, in common with conventional fluorescent markers. But importantly, silver clusters have an attractive set of features, including subnanometer size, nontoxicity and photostability, which makes them competitive as fluorescent markers compared with organic dye molecules and semiconductor quantum dots. In this chapter, we review the synthesis and properties of fluorescent silver clusters, and their application as bio-labels and molecular sensors. Silver clusters may have a bright future as luminescent probes for labeling and sensing applications. 

Dintz IL, Uyeda HT, Goldman ER, Mattoussi H (2005). Quantum dot bioconjugates for imaging, labelling and sensing. Nature Mater. 4 435 146. 

NANOSCALE SENSING ASSEMBLIES USING QUANTUM DOT-PROTEIN BIOCONJUGATES... 

Chapter 14, Nanoscale Sensing Assemblies Using Quantum Dot-Protein Bioconjugates, also describes a kind of sensor technology in that ultra-small size, but one using a very different approach. 

CdSe quantum dots have been used extensively in sensing and tagging applications. To take one supramolecular example, CdSe nanocrystals derivatised with simple aromatic groups at the cluster surface have been shown to bind and intercalate organic cations allowing them to penetrate near to the cluster core with consequent effects on the cluster photoluminescence, particularly quenching via k—k interactions.40... 

Quantum Dots (QDs) Use of quantum dots, luminescence as a detection method, with organic groups and biomolecules as functionalization materials, in sensing applications. 

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