Affinity sensors

We believe that the paper on optical affinity sensors for individual metabolites by Schultz Sims18 was a milestone paper in optical waveguide... 

Fiber Optic Affinity Sensors, Immunosensors and Gene Sensors... 

Schultz J.S., Sims G., Affinity sensors for individual metabolites, Biotechnol. Bioeng. Symp. 1979 9 65. 

The background problem can be further overcome when using a surface-confined fluorescence excitation and detection scheme at a certain angle of incident light, total internal reflection (TIR) occurs at the interface of a dense (e.g. quartz) and less dense (e.g. water) medium. An evanescent wave is generated which penetrates into the less dense medium and decays exponentially. Optical detection of the binding event is restricted to the penetration depth of the evanescent field and thus to the surface-bound molecules. Fluorescence from unbound molecules in the bulk solution is not detected. In contrast to standard fluorescence scanners, which detect the fluorescence after hybridization, evanescent wave technology allows the measurement of real-time kinetics (www.zeptosens.com, www.affinity-sensors.com). 

J. Halamek, A. Makower, K. Knosche, P. Skladal and F.W. Scheller, Piezoelectric affinity sensors for cocaine and cholinesterase inhibitors, Talanta, 65 (2005) 337-342. 

J. S. Schultz, S. Mansouri, and I. Goldstein, Affinity sensor A new technique for developing implantable sensors for glucose and other metabolites, Diabetes Care 5, 245-253 (1982). 

K. R. Srinivasan, S. Mansouri, and J. S. Schultz, Coupling of concanavalin A to cellulose hollow fibers for use in glucose affinity sensor, Biotechnol. Bioeng. 23, 233 (1986). 

S.J. Setford, R.M. Van Es, Y.J. Blankwater and S. Kroger, Receptor binding protein amperometric affinity sensor for rapid /Mactam quantification in milk, Anal. Chim. Acta, 398 (1999) 13-22. 

Ballerstadt R, Evans C, Gowda A, McNichols R. In vivo performance evaluation of a transdermal near-infrared fluorescence resonance energy transfer affinity sensor for continuous glucose monitoring. Diabetes Technology Therapeutics 2006, 8, 296-311. 

A simplified theory of FRET is sufficient to describe affinity sensors used in fluorescence transduction of glucose concentrations. A key quantity that describes the potential FRET interaction between a donor-acceptor pair is the Forster distance, Ro, the distance at which half the donor molecules are quenched by the acceptor molecules. Ro is proportional to several parameters of the fluorophores, in accordance with Ro = K6 Jx2n 4 cf>DJ l], where K is a constant. The variable k2 refers to the relative spatial orientation of the dipoles of D and A, taking on values from 0 to 4 for completely orthogonal dipoles and collinear and parallel transitional dipoles k2 = 4,... 

Ballerstadt R, Polak A, Beuhler A, Frye J. In vitro long-term performance study of a near-infrared fluorescence affinity sensor for glucose monitoring. Biosensors Bioelectronics 2004, 19, 905-914. 

Meadows DL, Schultz JS. Design, manufacture and characterization of an optical fiber glucose affinity sensor based on an homogeneous fluorescence energy transfer assay system. Analytica Chimica Acta 1993, 280, 21-30. 

Figure 11.4 Schematic of SWNT affinity sensor. Dextran-coated SWNT aggregates upon addition of Con A, resulting in a fluorescence decrease. Addition of glucose induces aggregate dissolution and a fluorescence recovery. Adapted with permission from Ref. 29.

SWNT-based glucose sensors an enzyme-based sensor and an affinity sensor. These results are a promising beginning however, there is much work left to do before the promise of SWNT in vivo sensors is realized. Investigation of new sensing modalities and optimization of current ones is necessary before the best nanotube-based sensing strategy is discovered. 

Barone PW, Strano MS. Reversible control of carbon nanotube aggregation for a glucose affinity sensor. Angewandte Chemie, International Edition 2006, 45, 8138-8141. 

A.J. Schuetz, M. Winklmair, M.G. Weller and R. Niessner. Multianalyte detection with an affinity sensor array, Bioluminescence and Chemiluminescence - Perspectives for the 21st Century (Ed. by A. Roda, M. Pazzagli, L.J. Kricka and P.E. Stanley, pp. 67-70). Proc. 10th Intern. Symp., 1998, Bologna, John Wiley Sons, Chichester, 1999. Available at http //www.ch.tum.de/ wasser/weller/BC99b.pdf. 

Schuderer J, Akkoyun A, Brandenburg A et al (2000) Development of a multichannel fluorescence affinity sensor system. Anal Chem 72 3942-3948... 

Reversible immobilization also can be used for analytical techniques such as affinity sensors or flow injeaion binding aissays (see later in this chapter for a description). 

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