[...]... encoded with unique optical signatures The resulting three types of beads were randomly distributed into a microwell array and used for the analysis of three different target sequences simultaneously 36 Optrode-based Fiber Optic Biosensors W 0 i _ ~ - -_ _:, _ _ - 8 -5 \ N o CM 2 0 0 nM Co ~Q % -IO % I '-% % -1 5 I~uM H64C- CY3-a~poCA FIBER: 20OHM... were developed and reported in several books (Blum et al., 19 94; Wolfbeis, 19 91) , and reviews (Aboul-Enein et al., 2000; Fraser, 19 95; Mehrvar et al., 2000; Rabbany et al., 19 94; Wolfbeis, 2000) Although the bio-optrode basic configuration has not changed much from the one proposed by Lubbers and Opitz (19 75), new types of optical fibers, optical instruments, biorecognition molecules and indicators... chemiluminescence in biosensors, including fiber optic-based biosensors, was recently reviewed (Aboul-Enein et al., 2000; Gubitz et al., 20 01) In many bio-optrodes, the chemiluminescence of luminol is used to generate the light signal The reaction between luminol and H2Oz produces a 12 Optrode-based Fiber Optic Biosensors Figure 5 Design of flow-cells incorporating bio-optrodes (Kuswandi et al., 20 01) Reproduced... advantages over larger bio-optrodes including fast response time and higher sensitivity Using BPT nano bio-optrodes, BPT concentrations as low as 300 zeptomoles were detected (Vo-Dinh et al., 20 01) 27 Biran and Walt Figure 13 Measurements inside a single live cell using a nano bio-optrode (a) The optical measurement system (b) A nano bio-optrode inside a single cell (Vo-Dinh et al., 20 01) Reprinted with permission... chemistry (Wilchek and Bayer, 19 90) The fiber surface can be modified with biotin groups and bind avidin-modified biomolecular conjugates or vice versa This method is very attractive since many biotin -~ or avidin-labeled enzymes, antibodies and nucleic acids are commercially available 2 History Optical fiber-based biosensors evolved from chemical optrodes The first optical fiber-based chemical sensor... Lubbers and Opitz (19 75) Their device was designed to measure CO2 and 02 and was used in biological fluids A few years later, biological molecules were coupled to the optical fiber-based chemical sensors and bio-optrodes were formed One of the first bio-optrodes involved coupling the enzyme glucose oxidase to an Oz optrode to fabricate a glucose biosensor (Arnold, 19 85) In the following years, many bio-optrodes... iran and Walt Figure 16 Imaging fiber-based penicillin and pH bio-optrode (a) Response of biooptrode, similar to the one described in Figure 15 , with penicillin-sensitive polymer regions (containing the enzyme penicillinase) and pH-sensitive polymer regions When the penicillin concentration is increased, only the fluorescence intensity from the penicillin-sensitive polymer regions increases (b) Bio-optrode... devices, which 15 Biran and Walt Table 1 Li ;ht sources Wavelength Characteristics (nm) IR/NIR, visible High power output, bulky, expensive, 20 0-3 00 used together with wavelength selection device 20 0 -1 000 47 0 -1 300 LOW power Output, high stability, long life, robust, compact size, inexpensive 377, ~18 8-5 68, Monochromatic, very high power 633 output, directional, bulky, expensiv e 80 0-9 04 High power... biocatalysts (enzymes and cells), and bioaffinity molecules (antibodies, receptors, and nucleic acids) 1. 4 .1 Biocatalyst-based optrodes Enzymes are proteins that selectively bind and catalyze the conversion of a substrate to product Enzymes are used as sensing elements in bio-optrodes based on their ability to bind specific substrates (e.g., the analyte) and catalyze their conversion into an optically detectable... from these two fields has led to the development of advanced bio-optrode technologies such as multianalyte bio-optrodes, reagentless bio-optrodes and nano bio-optrodes 3 Advanced Bio-Optrode Technologies and Applications In this section, a few examples of new bio-optrode technologies and applications will be described Although many novel and interesting papers related to biooptrode developments have . the ideas and accomplishments of our fellows, we delight in their personalities and camaraderie. Sincerely, Fran and Chris viii Optical Biosensors: Present and Future F.S. Ligler and C.A Rogers and Poziomek, 19 96; Marose et al., 19 99; Mulchandani and Bassi, 19 95; Scheper et al., 19 96). In this section, optical fibers, their basic characteristics, and the optical methods used. (Meadows, 19 96; Vo-Dinh and Cullum, 2000). Bio- optrodes are also useful for different sensing applications in the industrial and environmental fields (Rogers and Mascini, 19 98; Rogers and Poziomek,