University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Otto S. Wolfbeis

Abbrev:
Wolfbeis, O.S.
Other Names:
Address:
Institute of Analytical Chemistry, University of Regensburg, D-93040 Regensburg, Germany
Phone:
+49-941-943-4065
Fax:
+49-941-943-4064

Citations 8

"Optical Sensors In Flow Injection Analysis"
J. Mol. Struct. 1993 Volume 292, Issue 3 Pages 133-140
Otto S. Wolfbeis

Abstract: Representative examples are given on how optical chemical sensors (optrodes) can be coupled to flow injection systems to result in flow injection analyzers. These have served two main purposes so far, namely testing the performance of optrodes, and secondly as detectors in flow injection analysis (FIA). Specifically, the use of optrodes sensitive to pH, oxygen, ammonia and other chemical species as detectors in FIA will be described, all mainly in conjunction with enzymatic reaction schemes. Finally, optrodes are shown to be useful for determination of enzyme activity and enzyme inhibition by heavy metals.
Sensor

"Fiber Optic Multi-channel Protein Detector For Use In Preparative Continuous Annular Chromatography"
J. Chromatogr. A 2002 Volume 967, Issue 2 Pages 183-189
Athanasios Apostolidis, Hartmut Lehmann, Günter Schwotzer, Reinhardt Willsch, Albert Prior, Jürgen Wolfgang, Ingo Klimant and Otto S. Wolfbeis

Abstract: Continuous annular chromatography is an effective method in the separation of preparative scale quantities of biological compounds including proteins where established batch chromatography borders on it. The need for identification or quantification of proteins triggered the development of respective detection units. Here, we describe two types of optical multi-channel detectors. The first is a fiber optic multi-channel detector suitable for the separation of aqueous protein solutions. The second is a technically improved (circular optic) device suitable for application in multi-channel detection. Specifically, UV-absorption measurements of proteins at 280 nm were carried out using newly designed fiber optic detectors having eight and 16 channels, Calibration plots were established for a series of stock solutions of known concentrations of proteins, Mathematical functions were derived from these calibration data to simulate the response of the detector. Limits of detection and the ranges of validity of the fit functions were determined. The 16-channel detector has a theoretical limit of detection that is equivalent to absorbance changes of 10^-4 Units. (C) 2002 Elsevier Science B.V. All rights reserved.

"A Fully Reversible Fiber Optic Lactate Biosensor Based On The Intrinsic Fluorescence Of Lactate Monooxygenase"
Fresenius J. Anal. Chem. 1989 Volume 334, Issue 5 Pages 427-430
Wolfgang Trettnak and Otto S. Wolfbeis

Abstract: The intrinsic fluorescene intensity of the enzyme lactate monooxygenase is used as the analytical parameter in a new type of lactate biosensor. it is found that the fluorescence quantum yield of coenzyme changes during its interaction with lactate at the point of saturation. The changes in intensity are fully reversible in the presence of molecular oxygen and can be monitored via fiber optic light guides. Enzyme solutions were entrapped at the fiber end using a semipermeable membrane which retains the enzyme. The change in fluorescence occurs within a rather small range of lactate concentration (0.5-1 mmol/l) with an lactate-invariable signal at higher levels. Response times of 7.5 to 25 min (to reach the full steady state) and regeneration times between 1 and 8 min are observed. Measurements are performed in flowing air-saturated solutions containing 0.1 mol/l pH 7.0 citrate buffer. The effect of pH has also been investigated. In order to achieve a more expanded analytical range (e.g., 1.4-10 mmol/l) and shorter response times, kinetic measurements are performed in a fashion similar to flow injection analysis.
Lactate Fluorescence Sensor Kinetic Optical fiber Steady state

"Nonimmunological Assay Of Urinary Albumin Based On Laser-induced Fluorescence"
Clin. Chem. 1992 Volume 38, Issue 10 Pages 2089-2092
MA Kessler, MR Hubmann, BA Dremel and OS Wolfbeis

Abstract: We describe the first nonimmunological assay of albumin in urine with a detection limit of 1 mg/L. The method is simple, rapid, and accurate. It is based on the probe Albumin Blue 670, which becomes highly fluorescent on binding to albumin. An inexpensive diode laser was used as the light source for measurement of laser-induced fluorescence. The assay was coupled to a flow injection analysis system capable of running 20 samples per hour. The working range was 1-100 mg/L, which covered albumin concentrations found in nonpathological urine and in urine with slightly increased albumin. This range makes prediction of nephropathy possible at an early stage. Other serum proteins and hemoglobin do not interfere. The coefficients of variation were < 4% and < 7% within one day and from day to day, respectively. A correlation coefficient of 0.990 (n = 100) was obtained for comparison with the Behring nephelometric assay.
Albumin Urine Fluorescence Clinical analysis Laser diode Interferences Method comparison

"Composite Films Of Prussian Blue And N-substituted Polypyrroles: Covalent Immobilization Of Enzymes And Application To Near Infrared Optical Biosensing"
Biosens. Bioelectron. 1999 Volume 14, Issue 1 Pages 87-92
Robert Koncki and Otto S. Wolfbeis

Abstract: We demonstrate the feasibility of optical biosensing using a material which, in essence, is a modified inorganic film to which various enzymes were covalently attached. Thin and transparent blue films composed of Prussian blue and incorporated into a network of N-substituted polypyrroles are sensitive to pH in the 5-9 range at 720 nm wavelength and can be modified with enzymes to result in the respective biosensors. Several methods of enzyme immobilization, using bifunctional crosslinking reagents, and various enzymes were tested. The best results were obtained using the one-step carbodiimide method which resulted in highly active, stable and transparent biosensor films for optical determination of urea and acetylcholine. The operational stability exceeded 1 month and even after 2 months of dry storage at room temperature the activity did not drop. The biosensors allow optical determination of the respective substrates in the millimolar concentration range.

"Fiber Optic Chemical Sensors And Biosensors"
Anal. Chem. 2000 Volume 72, Issue 12 Pages 81R-89R
Otto S. Wolfbeis

Abstract: A review with many references. This review is divided into sections on books and reviews (A), on specific sensors for gases and vapors (B), ions (C), and organic species (D), respectively, followed by sections on biosensors (E) and by chapters on application-oriented sensor types (F), sensing schemes (G), and sensor materials (H), respectively
Sol-gel Review

"Optical Fibre Sensor For Biological Oxygen Demand"
Anal. Chem. 1994 Volume 66, Issue 11 Pages 1841-1846
Claudia Preininger, Ingo Klimant, and Otto S. Wolfbeis

Abstract: The cited biosensor (illustrated) comprised a sensing membrane mounted at the tip of an optical fiber. The membrane consisted of an optically-transparent gas-permeable polyester support on which layers of tris[4,7-diphenyl-1,10-phenanthroline]ruthenium(II) perchlorate (an O2-sensitive fluorescent material), charcoal (as an optical isolator), yeast cells (Trichosporon cutaneum) immobilized in poly(vinyl alcohol) and a substrate-permeable polycarbonate membrane were sequentially placed. The sensor was incorporated in a continuous-flow system with a 150 W pulsed Xe light source and a photomultiplier as detector; a 480 nm interference filter was used to isolate the appropriate excitatory light and a 560 nm long-pass filter was used to collect the red fluorescence (λmax = 610 nm). The calibration graph was linear for a BOD of up to 110 mg/l for a glucose/glutamate standard and the detection limit was ~2-3 mg/l; the RSD was 4%. The response time was 5-10 min. The method was applied to untreated sewage plant effluents and the results correlated well with those obtained by the conventional dilution method.
Glucose Glutamate Biological oxygen demand Waste Waste Sensor Fluorescence Optical fiber Method comparison Immobilized cell Interferences

"Determination Of Urease Activity By Flow Injection Analysis Using An Ammonium-selective Optrode As The Detector"
Anal. Chim. Acta 1993 Volume 276, Issue 1 Pages 115-119
Hong Li and Otto S. Wolfbeis*

Abstract: The cited method was performed with a flow injection manifold composed of an autosampler, a peristaltic pump, an injection valve with a 200 µL sample loop and a flow cell containing the ammonium-sensitive membrane placed at the end of the optical fiber (schematic diagram given), with a carrier stream of 50 mM Tris - HCl buffer of pH 7.1. The ammonium ions formed by the enzymatic hydrolysis of urea were measured fluorimetrically using the sensor membrane based on an ion-exchange sensing scheme using nonactin as the ion carrier. Optical measurements were performed with a optical-fiber photometer equipped with a Xe lamp pulsed at 9 Hz. Calibration graphs were rectilinear from 1 to 30 iu mL-1 and the coefficient of variation at 3 iu mL-1 was 3.7%.
Enzyme, urease Fluorescence Optrode Optical fiber