University of North Florida
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Contact Info

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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Nabil El Murr

Abbrev:
El Murr, N.
Other Names:
Address:
LAIEM, Faculté des sciences et des techniques, 2 rue de la Houssinière, BP 92208, F-44322 Nantes 03, France
Phone:
02 51 12 56 98
Fax:
02 51 12 56 92

Citations 5

"Rapid And Sensitive Automated Method For Glucose Monitoring In Wine Processing"
J. Agric. Food Chem. 2004 Volume 52, Issue 18 Pages 5588-5592
Simona Serban, Andrei F. Danet and Nabil El Murr

Abstract: A rapid and sensitive automated method for glucose monitoring that might be employed during wine fermentation and processing was developed. A flow injection (FI) system coupled with an automated dilutor and the 'redox-versatile' modified electrode were used to directly measure glucose in wine. To avoid interferences during wine analysis, different formulations of enzymatically modified carbon paste electrodes (CPE) were used and evaluated in oxidation and reduction mode. The best selectivity and sensitivity for glucose monitoring in real samples was obtained in cathodic mode at a fixed potential of 0 V versus Ag/AgCl using a CPE modified with glucose oxidase, horseradish peroxidase, and ferrocene as redox mediator. A total linear range of 0.02-50 g/L glucose was covered using this automated system and allowed the measurement of glucose in dry, medium, and sweet white or red wines without any sample pretreatment. The results showed a good correlation with the standard method, and the proposed method is very rapid, simple, and reliable and does not need skilled operators. Keywords: Wine; glucose biosensor; enzymatic electrode; automated flow injection analysis

"New Strategy For Dehydrogenase Amperometric Biosensors Using Surfactant To Enhance The Sensitivity Of Diaphorase/Ferrocene Modified Carbon Paste Electrodes For Electrocatalytic Oxidation Of NADH"
Electroanalysis 2003 Volume 15, Issue 13 Pages 1095-1100
César Ramírez-Molina, Mohammed Boujtita, Nabil El Murr

Abstract: A carbon paste electrode (CPE) modified with diaphorase (DAP) and ferrocene (FcH) has been developed for determination of NADH at low working potential. The sensitivity and operational stability, towards the detection of the reduced form of the nicotinamide adenine dinucleotide (NADH) in flow injection analysis (FIA), were greatly improved (5 times) upon adding Tween 20 into the electrode matrix. The magnitude of the amperometric signal was dependent on DAP, FcH and surfactant loading, into the modified carbon paste electrode. A rapid and repeatable response was observed to the variation of NADH concentration in the vicinity of the electrode surface. Such advantages of the DAP/FcH/Tween 20 modified carbon paste were successfully used in the construction of L-lactate dehydrogenase modified electrodes. The use of this new approach can be generalized to other dehydrogenases and represents a decisive step for a versatile preparation method of amperometric biosensors.

"Layer-by-layer Hydroxymethyl Ferrocene Modified Sensor For One-step Flow/stop-flow Injection Amperometric Immunoassay Of -fetoprotein"
Biosens. Bioelectron. 2007 Volume 22, Issue 8 Pages 1700-1706
Zong Dai, Simona Serban, Huangxian Ju and Nabil El Murr

Abstract: A rapid one-step flow/stop-flow injection amperometric immunoassay for ?-fetoprotein (AFP) using a novel home-produced electrochemical sensor was proposed. The sensor was prepared using layer-by-layer adsorption of positively charged poly(allylamine) (PAA) and negatively charged hydroxymethyl ferrocene on a screen-printed electrode (SPE). The electrochemistry of the immobilized ferrocene moieties showed a surface-controlled electrode process. Based on an electrochemical enzyme-linked immunoassay with the immobilized ferrocene moieties as an electron transfer mediator between the electrode and the horseradish peroxidase (HRP)-labeled anti-AFP antibody, a calibration curve with two linear ranges from 5 to 20 and 20 to 150 ng mL-1 and a detection limit of 2 ng mL-1 for AFP determination was obtained under the optimized conditions of 0.891 mL min-1 flow rate, 20 µL injection volume and +25 mV applied potential. The sensor showed good repeatability and reproducibility and retained more than 95% of its original signal after 15 days of storage. The proposed method eliminated the need for washing and addition of any substrate or mediator. The complete assay could be handled in less than 25 min with a one-step injection of a 40 µL sample solution. The proposed method would be valuable for the diagnosis and monitoring of carcinoma and its metastasis. © 2006 Elsevier B.V. All rights reserved.

"The Synergetic Effect Of Redox Mediators And Peroxidase In A Bienzymatic Biosensor For Glucose Assays In FIA"
Analusis 1999 Volume 27, Issue 7 Pages 649-656
A. Rondeau, N. Larsson, M. Boujtita, L. Gorton and N. El Murr

Abstract: A bienzymatic biosensor incorporating a mediator has been developed in order to achieve a fast and selective detection of glucose in a flow injection system. The working electrode is based on a carbon paste matrix bulk modified with glucose oxidase (GOD) and horseradish peroxidase (HRP) as well as with ferrocene acting as an electron transfer mediator between the electrode and HRP. The proximity of these three components enhances the electron transfer within the electrode. Simple polishing on a paper sheet easily renews the electrode surface. Moreover, the applied working potential (-0.050 V vs. Ag/AgCl) is low hereby decreasing the interference from electroactive compounds and thus increasing the selectivity of the biosensor. The characteristics of the developed bienzymatic electrode are presented in terms of sensitivity, linear detection range, accuracy and operational stability.
Glucose

"Biosensor For Determination Of Glucose And Sucrose In Fruit Juices By Flow Injection Analysis"
Appl. Biochem. Biotechnol. 2000 Volume 89, Issue 2-3 Pages 171-181
Guémas, Yann; Boujtita, Mohamed; El Murr, Nabil

Abstract: Glucose and sucrose were measured with an amperometric method by using the flow injection analysis technique. A carbon paste electrode with a renewable surface containing glucose oxidase, horseradish peroxidase, and ferrocene was used in combination with the soluble enzymes invertase and mutarotase. The Effect of invertase, mutarotase, and ascorbic acid on the electrode response was examined. Glucose and sucrose concentrations were determined with <3% errors. The proposed method for glucose and sucrose measurements was validated in real samples of fruit juices. The results were also compared with those obtained with the ultraviolet method.
Glucose