Fluorescence-based sensing

Ohuchi Y, Katayama Y, Maeda M (2001) Fluorescence-based sensing of protein kinase A activity using the dual fluorescent-labeled peptide. Anal Sci 17 il465—i 1467... 

As opposed to conventional analytical techniques, optical sensors and biosensors, particularly those employing absorption and fluorescence-based sensing materials potentially allow for measurement through transparent or semi-transparent materials in a non-destructive fashion4, 5> 9 10. Chemical sensor technology has developed rapidly over the past years and a number of systems for food applications have been introduced and evaluated with foods. 

Contact lenses are attractive formats for fluorescence-based sensing, as they are optically transparent, easily accessible, and are sufficiently inexpensive to be disposable. A handheld device for patients to self-test has been developed to excite and measure fluorescence from lenses (Figure 10.9) and some limited clinical trials have been performed.143 144 However, the efficacy of using tear fluid to manage diabetes... 

Fluorescence-based sensing systems offer the possibility of high levels of sensitivity and MIPs containing reporter molecules have been the subject of considerable research. There are two ways in which this may be achieved within MIPs. The simpler of the two is simply imprinting a molecule with inherent fluorescence, as demonstrated by Matsui et al. in the imprinting of cinchonidine and cinchonine. More challenging is the placement of a... 

Llorent-Martmez, E. J., J. F. Garcia-Reyes, P. Ortega-Barrales, and A. Molina-Diaz. 2006. A multicommuted fluorescence-based sensing system for simultaneous determination of Vitamins B2 and B6. Anal. Chtm. Acta 555 128-133. 

Later on, such S-layer-based sensing layers were also used in the development of optical biosensors (optodes), where the electrochemical transduction principle was replaced by an optical one [97] (Fig. 10c). In this approach an oxygen-sensitive fluorescent dye (ruthenium(II) complex) was immobilized on the S-layer in close proximity to the glucose oxidase-sensing layer [97]. The fluorescence of the Ru(II) complex is dynamically quenched by molecular oxygen. Thus, a decrease in the local oxygen pressure as a result of... 

Szmacinski, H. Lacowicz, J. R. Lifetime-based Sensing Using Phase-Modulation Fluorometry. In Fluorescent Chemosensor for Ion and Molecule Recognition. ACS Symposium Series 538, 1993. 

Wolfbeis O.S., Fluorescence-based ion sensing using potential-sensitive dyes, Sensor ActuatB-Chem 1995 29 140. 

Optical sensors rely on optical detection of a chemical species. Two basic operation principles are known for optically sensing chemical species intrinsic optical property of the analyte is utilized for its detection indicator lor label) based sensing is used when the analyte has no intrinsic optical property. For example, pH is measured optically by immobilizing a pH indicator on a solid support and observing changes in the absorption or fluorescence of the indicator as the pH of the sample varies with time1 20. 

Epstein J.R., Walt D.R., Fluorescence-Based Fibre Optic Arrays A Universal Platform For Sensing, Chem. Soc. Rev. 2003 32 203-214. 

While planar optical sensors exist in various forms, the focus of this chapter has been on planar waveguide-based platforms that employ evanescent wave effects as the basis for sensing. The advantages of evanescent wave interrogation of thin film optical sensors have been discussed for both optical absorption and fluorescence-based sensors. These include the ability to increase device sensitivity without adversely affecting response time in the case of absorption-based platforms and the surface-specific excitation of fluorescence for optical biosensors, the latter being made possible by the tuneable nature of the evanescent field penetration depth. 

Yet the majority of cation sensors are mediator-based sensing. One type of optical sensor is based on the fluorescence quenching of fluor-ophore Rhodamine 6G by transition metals such as Co(II), Cr(III),... 

For the reaction-based sensing of anions, the most considerable success has been reached in cyanide sensing, basically due to the necessity for assessing this toxic species and because it can be easily addressed in water due to its high nucleophi-licity. For instance, the coumarin derivative 50 shows a dramatic fluorescence increase after cyanide-induced cyanohydrin reaction (Fig. 19), no response to... 

Tsagkatakis I, Peperv S, Retter R, Bell M, Bakker E (2001) Monodisperse plasticized poly (vinyl chloride) fluorescent microspheres for selective ionophore-based sensing and extraction. Anal Chem 73 6083-6087... 

Towards fluorescence-based chemical sensing devices 333... 

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