A novel fiber‐optic pH sensor incorporating carboxy SNAFL‐2 and fluorescent wavelength‐ratiometric detection

Xu, Zhong; Rollins, Andrew M.; Alcala, Ricardo; Marchant, Roger

doi:10.1002/(sici)1097-4636(199801)39:1<9::aid-jbm2>3.3.co;2-7

Cited by 4 publications

(4 citation statements)

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“…Given a fluorescent indicator that exhibits a shift in excitation or emission wavelength with pH, the ratio of the emission intensity at the two wavelengths can be used as a robust measure of the pH that is insensitive to orientation, probe concentration, and background fluorescence. Fiber-optic sensors based on fluorescein (7), seminaphthofluorescein (8), and carboxynaphthofluorescein (9) have been described that rapidly and reliably correlate intensity ratios to pH. The extensive photobleaching that is observed for these dyes is accounted for by the ratiometric approach but would still limit the useful lifetime of the sensor.…”

Section: Introductionmentioning

confidence: 99%

Dual Excitation Ratiometric Fluorescent pH Sensor for Noninvasive Bioprocess Monitoring: Development and Application

Kermis

Kostov

Harms

et al. 2002

Biotechnology Progress

158

103

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The development and application of a fluorescent excitation-ratiometric, noninvasive pH sensor for continuous on-line fermentation monitoring is presented. The ratiometric approach is robust and insensitive to factors such as source intensity, photobleaching, or orientation of the patch, and since measurements can be made with external instrumentation and without direct contact with the patch, detection is completely noninvasive. The fluorescent dye 8-hydroxy-1,3,6-pyrene trisulfonic acid was immobilized onto Dowex strongly basic anion-exchange resin, which was subsequently entrapped into a proton-permeable hydrogel layer. The sensor layer was polymerized directly onto a white microfiltration membrane backing that provided an optical barrier to the fluorescence and scatter of the fermentation medium. The ratio of emission intensity at 515 nm excited at 468 nm to that excited at 408 nm correlated well with the pH of clear buffers, over the pH range of 6-9. The sensor responded rapidly (<9 min) and reversibly to changes in the solution pH with high precision. The sterilizable HPTS sensor was used for on-line pH monitoring of an E. coli fermentation. The output from the indwelling sensor patch was always in good agreement with the pH recorded off-line with an ISFET probe, with a maximum discrepancy of 0.05 pH units. The sensor is easily adaptable to closed-loop feedback control systems.

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Section: Introductionmentioning

confidence: 99%

Dual Excitation Ratiometric Fluorescent pH Sensor for Noninvasive Bioprocess Monitoring: Development and Application

Kermis

Kostov

Harms

et al. 2002

Biotechnology Progress

158

103

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“…One option for overcoming these problems is to use the emerging technology of optical chemical sensing (Bambot et al, 1994;Randers-Eichhorn et al, 1997;Xu et al, 1998). As these sensors are typically based on equilibrium principles, they do not interfere with the measured process.…”

Section: Introductionmentioning

confidence: 99%

Low-cost microbioreactor for high-throughput bioprocessing

Kostov

Harms

Randers‐Eichhorn

et al. 2000

Biotechnol. Bioeng.

186

126

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The design of a microbioreactor is described. An optical sensing system was used for continuous measurements of pH, dissolved oxygen, and optical density in a 2 mL working volume. The KLa of the microbioreactor was evaluated under different conditions. An Escherichia coli fermentation in both the microbioreactor and a standard 1 L bioreactor showed similar pH, dissolved oxygen, and optical density profiles.%The low cost of the microbioreactor, detection system, and the small volume of the fermentation broth provide a basis for development of a multiple‐bioreactor system for high‐throughput bioprocess optimization. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 72: 346–352, 2001.

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“…Due to its high sensitivity, fluorescence-based OCS is the most widely used method. Luminescent probes are reported for various analytes, such as pH [173,181,190,[554][555][556][557][558][559][560][561][562][563][564] , CO 2 [565][566][567][568][569][570][571][572][573][574] and ammonia [575][576][577][578][579] (both via pH/ H + indicators), O 2 [175,178,180,182,323,[580][581][582][583] (reviewed in detail in [175,323,584] ), Na + [585][586][587] , K + [585,[588][589][590]...…”

Section: Discussionmentioning

confidence: 99%

Label-free and Multi-parametric Monitoring of Cell-based Assays with Substrate-embedded Sensors

Oberleitner

2018

Springer Theses

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These cellular responses and the accompanying changes of physicochemical parameters are what is to be detected and transferred into a measurable electrical signal by the transducer units of the label-free biosensor devices (Fig. 1-1). There are various types of transducers, distinguishable by the underlying physicochemical phenomenon: electrochemical (including potentiometric, amperometric, and impedimetric), optical, thermometric, piezoelectric, and magnetic transduction. [8] Tab. 1-1 gives an LAPSLight-addressable potentiometric sensors (LAPSs) are multilayer field-effect devices similar to ISFETs [66] . A LAPS consists of a doped semiconductor covered with an insulator layer and a chemosensitive layer. The device is immersed in an electrolyte solution. The semiconductor is connected with a reference electrode in contact with the electrolyte (Fig. 1-2 B; reviewed in [10,17,[67][68][69][70] with respect to biological and cell-based applications). The insulator material of LAPSs is typically made up either of a single SiO 2 layer 1.1 Label-free Biosensors for Cell-based Assays 7 chip-based systems for the label-free and continuous monitoring of DO in cell-based assays, i.e. the oxygen consumption rate (OCR) of cells. [47,48,50,53,54,57,[60][61][62] The sensor chips with integrated amperometric oxygen sensors are typically build up as multi-parametric sensors and contain further physicochemical transducer structures like e.g. for cell morphology testing and ECAR monitoring. Besides the direct measurement of DO, the amperometric sensors are also capable of sensing indirectly any species that is consumed or produced in an oxidase-based enzymatic reaction (amperometric enzyme sensor) via the oxygen or hydrogen peroxide concentration. For this purpose, the amperometric pO 2 sensor is coated with a layer in which the respective enzyme is immobilized and which enables free diffusion of all reactants between the bulk solution and the sensor surface. This approach was first presented by Clark and Lyons as an amperometric sensor for glucose [85] and has also been applied as transduction method in cell-based assays for the label-free determination and monitoring of glucose and lactose [78,79] . A list of physiologically relevant analytes that have been successfully monitored by amperometric enzyme sensors is given in [86] . ECISElectrical impedance-based sensing of adherent cells, also termed as electric cell-substrate impedance sensing (ECIS), utilizes the property of cells to impede AC current flow when they are in close contact to the substrate, i.e. a small gold-film working electrode (Fig. 1-2 D). This technique was presented first by Giaever and Keese in 1984 [87] as "morphological biosensor for mammalian cells" [88] . The principle of ECIS, the method of impedance spectroscopy, and the analysis, physiological meaning, and modeling of impedance data are extensively addressed in the methods section 3.4 Electric Cell-Substrate Impedance Sensing (ECIS). Briefly summarized, ECIS enables the time-resolved, label-free, and ...

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A novel fiber‐optic pH sensor incorporating carboxy SNAFL‐2 and fluorescent wavelength‐ratiometric detection

Cited by 4 publications

References 0 publications

Dual Excitation Ratiometric Fluorescent pH Sensor for Noninvasive Bioprocess Monitoring: Development and Application

Dual Excitation Ratiometric Fluorescent pH Sensor for Noninvasive Bioprocess Monitoring: Development and Application

Low-cost microbioreactor for high-throughput bioprocessing

Label-free and Multi-parametric Monitoring of Cell-based Assays with Substrate-embedded Sensors

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