Sensors molecular

Here we focus on probably one of the most promising applications of NTs their abiUty to transport electrons or holes elEciently when modified by photoactive molecules, forming donor-acceptor nanohybrid models as a building block in 

---

Nichols CG (2006) KATP channels as molecular sensors of cellular metabolism. Nature 440(7083) 470-476... 

Cyclophanes or 7r-spherands have played a central role in the development of supramolecular chemistry forming an important class of organic host molecules for the inclusion of metal ions or organic molecules via n-n interactions. Particular examples are provided by their applications in synthesis [80], in the development of molecular sensors [81], and the development of cavities adequate for molecular reactions with possible applications in catalysis [82]. The classical organic synthesis of cyclophanes can be quite complex [83], so that the preparation of structurally related molecules via coordination or organometallic chemistry might be an interesting alternative. 

F. and Buuren, T.v. (2005) Comment on Gold nanoshells improve single nanoparticle molecular sensors . Nano Letters, 5, 809-810. 

Zinc carboxylate interactions have been exploited as part of a fluorescent molecular sensor for uronic acids. The sensors feature two interactions coordination of the carboxylate to the zinc and a boronic acid diol interaction.389 Photoluminescent coordination polymers from hydrothermal syntheses containing Zn40 or Zn4(OH)2 cores with isophthalate or fumarate and 4,4 -bipyridine form two- and three-dimensional structures. Single X-ray diffraction of both dicarboxylates identified the network structure.373... 

Fang JM, Selvi S, Liao JH et al (2004) Fluorescent and circular dichroic detection of monosaccharides by molecular sensors bis[(pyrrolyl)ethynyl]naphthyridine and bis [(indoili)ethynyl]naphthyridine. J Am Chem Soc 126 3559-3566... 

Valeur B., Leray I., Design principles of fluorescent molecular sensors for cation recognition, Coord. Chem. Rev. 2000 205 3. 

Unlike the dependence of Aeff on film thickness alone (dNc /dd) that is sometimes used as a figure of merit for guided mode molecular sensors, 5m0d captures both the index and thickness dependence of the sensor response in a single parameter. While Dopt does not uniquely determine the film response for other optical techniques such as ellipsometry and reflectance difference, once d and n of the film are known, the optical thickness can be evaluated and comparisons are made between guided mode sensors and other techniques. 

Densmore, A. Xu, D. X. Janz, S. Waldron, P. Mischki, T. Lopinski, G. Delage, A. Lapointe, J. Cheben, P. Lamontagne, B. Schmid, J. H, Spiral path high sensitivity silicon photonic wire molecular sensor with temperature independent response, Opt. Lett. 2008, 6, 596 598... 

The equivalent scalability for molecular sensors applies to the point of care. Scalable biosensors will enable high-capacity diagnostic capabilities to remain sufficiently affordable and small in size to stay in doctors offices or in hospitals... 

Connecting lumophores and receptors with spacers permits the build-up of modular systems of increasing logical complexity. Even the simplest of these systems can be powerful molecular sensors. 

Kovalchuk A, Bricks JL, Reck G et al (2004) A charge transfer-type fluorescent molecular sensor that lights up in the visible upon hydrogen bond-assisted complexation of anions. Chem Commun 1946-1947... 

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. 

Silver Clusters as Fluorescent Probes for Molecular Sensors. 325... 

The design of fluorescent sensors is of major importance because of the high demand in analytical chemistry, clinical biochemistry, medicine, the environment, etc. Numerous chemical and biochemical analytes can be detected by fluorescence methods cations (H+, Li+, Na+, K+, Ca2+, Mg2+, Zn2+, Pb2+, Al3+, Cd2+, etc.), anions (halide ions, citrates, carboxylates, phosphates, ATP, etc.), neutral molecules (sugars, e.g. glucose, etc.) and gases (O2, CO2, NO, etc.). There is already a wide choice of fluorescent molecular sensors for particular applications and many of them are commercially available. However, there is still a need for sensors with improved selectivity and minimum perturbation of the microenvironment to be probed. Moreover, there is the potential for progress in the development of fluorescent sensors for biochemical analytes (amino acids, coenzymes, carbohydrates, nucleosides, nucleotides, etc.). 

In fluorescent molecular sensors, the fluorophore is the signaling species, i.e. it acts as a signal transducer that converts the information (presence of an analyte) into an optical signal expressed as the changes in the photophysical characteristics of the fluorophore. In contrast, in an electrochemical sensor, the information is converted into an electrical signal. 

The present chapter is restricted to fluorescent molecular sensors, for which three classes can be distinguished (Figure 10.1) ... 

Class 3 fluorophores linked, via a spacer or not, to a receptor. The design of such sensors, which are based on molecule or ion recognition by a receptor, requires special care in order to fulfil the criteria of affinity and selectivity. These aspects are relevant to the field of supramolecular chemistry. The changes in photophysical properties of the fluorophore upon interaction with the bound analyte are due to the perturbation by the latter of photoinduced processes such as electron transfer, charge transfer, energy transfer, excimer or exciplex formation or disappearance, etc. These aspects are relevant to the field of photophysics. In the case of ion recognition, the receptor is called an ionophore, and the whole molecular sensor is... 

CEF Chelation or Complexation Enhancement of Fluorescence CEQ Chelation or Complexation Enhancement of Quenching Fig. 10.1. Main classes of fluorescent molecular sensors of ions or molecules. 

Several books and many reviews have been devoted to fluorescent molecular sensors (see Bibliography at the end of this chapter). This chapter will present only selected examples to help the reader understand the fundamental aspects and the principles. 

---