Optical fiber biosensors

Absorbance- and reflectance-based measurements are widespread, as there are many enzymatic reaction products or intermediates that are colored or if not, can react with the appropriate indicator. Sensors using acetylcholinesterase for carbamate pesticides detection are an example of indirect optical fiber biosensors. This enzyme catalyses the hydrolysis of acetylcholine with concomitant decrease in pH41 ... 

Use of optical fiber biosensors for real-time detection of biowarfare agents (BWA) especially those of bacterial cells, toxins, or spores in the air, soil, or environment has been investigated by the Naval Research Laboratory (Taitt et al, 2005). In addition, many laboratories are also employing fiber optic biosensors for detection of wide varieties of foodbome pathogens, which are discussed below. 

Ko, S., and Grant, S. A. (2006). A novel FRET-based optical fiber biosensor for rapid detection of Salmonella typhimurium. Biosens. Bioelectron. 21,1283-1290. 

Since the early 1980s, considerable research effort has been devoted to the development of fiber optic (FO) biosensors because their potential sensitivity, detection speed, and adaptability to a wide variety of assay conditions. The area of optical fibers biosensors is quite wide and numerous applications have been described in the literature, mainly via the evanescent wave detection [1,16—19]. A number of possibilities for FO sensing have been proposed and some of them have reached commercial development [1,16]. 

Fig. 5.4. Optical Fiber biosensor, (a) Extrinsic optical fiber is used for the guiding the light to and from the sensor area, (b) Intrinsic the receptor molecules are immobilized on the fiber core after decladding of the fiber. The detection is based on fluorescence labels.

Gifford E, Wang Z, Ramachandran S, Heflin JR (2007) Sensitivity control of optical fiber biosensors utilizing turnaround point long period gratings with self-assembled polymer coatings. Proc SPIE 6659 665900... 

Fig. 4 - An optic fiber biosensor for cocaine using a mAb against benzoylecgonine as the biological sensing element, (left) The time course of binding of FL-BE to the mAb-coated fiber expressed by the fluorescent signal transmitted via the fiber. After reaching steady state, FL-BE was withdrawn from the flow buffer (indicated by the arrow). The bound FL-BE dissociated and fluorescence decreased exponentially, (right) Reusability of the biosensor for multiple assays of cocaine introduced into the flow buffer after steady-state fluorescence (200 mV) was achieved. Cocaine at the indicated concentrations was added to the flow buffer for only the time intervals indicated by the bars. The downward deflection resulted from displacement of FL-BE by cocaine, but upon removal of cocaine from the flow buffer FL-BE displaced the bound cocaine. Reproduced with permission from reference 4, Copyright 1995 American Chemical Society.

Zhu L, Li YX, Zhu GY (2002) A novel flow through optical fiber biosensor for glucose based on luminol electrochemiluminescence. Sens Actuators, B 86(2-3) 209-214. doi 10.1016/s0925-4005(02)00173-9... 

Mascini, M. Enzyme-based optical-fiber biosensors. Sens. Actuators, B 1995, B29, 121—125. 

Zhu, L. D., Y. X. Li, F. M. Tian, B. Xu, and G. Y. Zhu, 2002. Electrochemiluminescent determination of glucose with a sol-gel derived ceramic-carbon composite electrode as a renewable optical fiber biosensor. Sens Actuat B-Chem 84 265—70. 

The dye is excited by light suppHed through the optical fiber (see Fiber optics), and its fluorescence monitored, also via the optical fiber. Because molecular oxygen, O2, quenches the fluorescence of the dyes employed, the iatensity of the fluorescence is related to the concentration of O2 at the surface of the optical fiber. Any glucose present ia the test solution reduces the local O2 concentration because of the immobilized enzyme resulting ia an iacrease ia fluorescence iatensity. This biosensor has a detection limit for glucose of approximately 100 ]lM , response times are on the order of a miaute. 

Moreno-Bondi 1990 fiber optic glucose biosensor (via oxygen)... 

Dremel B.A., Schaffar B.P., Schmid R.D., Determination of glucose in wine and fruit juice based on a fiber-optic glucose biosensor and flow-injection analysis, Anal. Chim. Acta 1989 225 293. 

Moreno-Bondi M.C., Wolfbeis O.S., Leiner M.J.P., Schaffar B.P.H., Oxygen optrode for use in a fiber optic glucose biosensor, Anal. Chem. 1990 62 2377. 

Trettnak W., Wolfbeis O.S., Fiber optic cholesterol biosensor with an oxygen optrode as the transducer Anal. Biochem. 1990 184 124. 

W. Trettnak, O.S. Wolfbeis, A fully reversible fiber optic lactate biosensor based on the intrinsic fluorescence of lactate monooxygenase, Fresenius Z. Anal. Chem. 1989, 334, 427. 

Sol-gel coating technique for optical chemical sensors and biosensors is now in extensive research phase. For example, the side-coating of optical fibers or waveguides in evanescent-wave sensors it is particularly important to control precisely the sensitivity determining parameters, such as the coating thickness and length45. 

The design and implementation of a portable fiber-optic cholinesterase biosensor for the detection and determination of pesticides carbaryl and dichlorvos was presented by Andreou81. The sensing bioactive material was a three-layer sandwich. The enzyme cholinesterase was immobilized on the outer layer, consisting of hydrophilic modified polyvinylidenefluoride membrane. The membrane was in contact with an intermediate sol-gel layer that incorporated bromocresol purple, deposited on an inner disk. The sensor operated in a static mode at room temperature and the rate of the inhibited reaction served as an analytical signal. This method was successfully applied to the direct analysis of natural water samples (detection and determination of these pesticides), without sample pretreatment, and since the biosensor setup is fully portable (in a small case), it is suitable for in-field use. 

Andreou V., Clonis Y., A portable fiber-optic pesticide biosensor based on immobilized cholinesterase and sol-gel entrapped bromocresol purple for in-field use, Biosens. Bioelectr. 2002 17 61-69. 

Kishen A., John M.S., Lim C.S., Asundi A., A fiber optic based biosensor to monitor mutants streptococci in saliva, SPIE Proc. 5068, 194-201, (2003). 

Rosenzweig Z., Kopelman R., Analytical properties and sensor size effects of a micrometer-sized optical fiber glucose biosensors, Anal. Chem. 1996 68 1408-1413. 

Ogert R.A., Shriver-Lake L.C., Ligler F.S., Toxin detection using a fiber optic-based biosensor, Proc. SPIE. 1885 11-17,1993. 

A. Mulchandani, I. Kaneva, and W. Chen, Biosensor for direct determination of organophosphate nerve agents using recombinant Escherichia coli with surface-expressed organophosphorus hydrolase. 2. Fiber-optic microbial biosensor. Anal. Chem. 70, 5042-5046 (1998). 

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