Hydrogel fluorescent sensor

O Neal DP, Meledeo MA, Davis JR, Ibey BL, Gant VA, Pishko MV, Cote GL (2004), Oxygen sensor based on the fluorescence quenching of a ruthenium complex immobilized in a biocompatible polyethylene glycol) hydrogel, IEEE Sensors Journal 4 728 - 734. 

In a related example, polyacrylamide hydrogel-based sensors functionalized with a thymine rich DNA which can simultaneously detect and remove mercury from water were fabricated [121]. Specifically, in the absence of Hg ", the DNA is in a random coil conformation, and the addition of SYBR Green I gives a weak fluorescence (Fig. 40a, yellow line). In the presence of Hg ", the DNA forms a hairpin structure yielding a ninefold emission increase. Using the naked eye, the... 

Mack AC, Jinshu M, McShane MJ. Transduction of pH and glucose-sensitive hydrogel swelling through fluorescence resonance energy transfer. IEEE Sensors 2005,2,912-915. 

FRET donor and acceptor can also be incorporated into the self-assembled nanofibers of supramolecular hydrogels. In this way Ikeda et developed a gel-based fluorocolorimetric sensor for polyols. The acceptor is boronic acid-appended. In the presence of polyols, it forms boronate ester complexes with the polyols, becomes negatively charged and more hydrophilic, and therefore migrates from the hydrophobic site. The increased distance between the donor and acceptor results in the fluorescence color change, from which the presence of polyols can be detected. 

Patrick, A. G. and Ulijn, R. V. (2007) Fluorescent hydrogel sensor particles for detection of elastase. Mat. Res. Soc. Proc., 1063-PP06-05. 

Tokuda T, Takahashi M, Uejima K, Masuda K, Kawamura T, Ohta Y, et al. CMOS image sensor-based implantable glucose sensor using glucose-responsive fluorescent hydrogel. Biomedical Optics Express 2014 5(ll) 3859-70. 

C. Ion sensing. Several different schemes can be applied to fiber-optic chemical sensors for detecting ions other than hydrogen. One approach is to design a system, similar to pH fiber-optic chemical sensors, in which a dye that selectively binds a metal ion of interest is immobilized in an ion-permeable polymer such as cellulose or a hydrogel at the tip of an optical fiber. The reaction between the dye and the ion changes the absorbance or fluorescence of such dyes. Absorbance or fluorescence intensity changes are measured as a function of ion concentration, but this... 

Reversibility of the transition renders the hydrogels attractive for sensor applications or controlled drug release. The hydrophobic core can be used to solubilize organic molecules such as fluorescent dyes or magnetic nanoparticles so... 

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