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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Jenny Emneus

Abbrev:
Emneus, J.
Other Names:
Jenny Emnéus
Address:
Department of Analytical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
Phone:
+46-46-222-4820
Fax:
+46 46 222 4544

Citations 10

"Evaluation Of Progesterone Content In Saliva Using Magnetic Particle-based Immuno Supported Liquid Membrane Assay (m-ISLMA)"
Biosens. Bioelectron. 2006 Volume 22, Issue 2 Pages 241-246
Madalina Tudorache, Izabela Anna Zdrojewska and Jenny Emnéus

Abstract: Progesterone in saliva was monitored using a new method called magnetic particle-based immuno supported liquid membrane assay (m-ISLMA) in a sequential injection (SI) setup, allowing automatic sample cleanup, analyte enrichment, and detection in a single analysis unit. Progesterone (Ag) diffuses from a continuous flowing sample - the donor - into a supported organic liquid membrane (SLM), based on analyte partitioning (solubility) between the aqueous donor and the organic phase. The Ag is re-extracted from the SLM into a second stagnant aqueous acceptor, containing antibodies (Ab) immobilized on magnetic beads, held at the bottom of the acceptor by a magnet. Due to the formation of strong Ag-Ab-bead complexes and a large excess of Ab-beads, the Ag is accumulated and selectively enriched in the acceptor. The extracted progesterone was quantified by injecting into the acceptor a horseradish peroxidase (HRP) labeled analyte tracer, the substrate (luminol, H2O2, and p-iodophenol), and finally detection of the generated chemiluminescence by a photomultiplier tube. After optimization of experimental parameters (e.g., sample flow rate, extraction time, type of organic solvent and antibody-bead concentration in the acceptor), a detection limit of 8.50 ± 0.17 fg L-1 and a dynamic range between 35 fg L-1 and 10 pg L-1 was reached. The progesterone level of saliva for three subjects (women in different period of ovarian cycle) was investigated, and the corresponding progesterone concentrations detected with m-ISLMA coincided well with the expected values. © 2006 Elsevier B.V. All rights reserved.

"A Chemiluminescence Flow Immunosensor Based On A Porous Monolithic Metacrylate And Polyethylene Composite Disc Modified With Protein G"
Biosens. Bioelectron. 2004 Volume 19, Issue 8 Pages 795-803
Seema Rani Jain, Ewa Borowska, Richard Davidsson, Madalina Tudorache, Einar Pontén and Jenny Emnéus

Abstract: A generic, fast, sensitive and new type of flow immunosensor has been developed. The basis is a monolithic porous poly(glycidyl methacrylate-co- trimethylolpropane trimethacrylate) polymer disc modified with protein G, placed in a fountain type flow cell compartment, in close proximity to a photomultiplier tube (PMT). Analyte and HRP labelled analyte derivative (tracer) compete for anti-analyte antibody binding sites. The mixture is then injected into the flow immunosensor system where the formed analyte- and tracer-antibody complexes are trapped by the monolithic protein G disc. The amount of bound tracer, inversely related to the concentration of analyte in the sample, is determined in a second step by injection of luminol, p-iodophenol and H 2O2, generating enhanced chemiluminescence (CL) with horseradish peroxidase (HRP). A third and final step is need for regeneration of the protein G disc so that a new analysis cycle can take place. The performance of the disc immunosensor system was compared with a one step continuous flow injection immunoassay (FIIA) system, using the same reagents and a protein G column, in terms of assay sensitivity and influence of matrix effects from various water samples (millipore-, tap- and surface water). The detection limit for the analyte atrazine in PBS and surface water (SW) was 0.208 ±0.004?gl-1 (PBS) and 0.59 ±0.120?gl -1 (SW) for the FIIA and 0.033 ±0.003?gl-1 (PBS) and 0.038 ±0.003?gl-1 (SW) for the disc immunosensor. Statistical comparison of the two systems shows that the disc immunosensor results were significantly less influenced by the sample matrix, which is explained by the fact that the sample in the FIIA arrives simultaneously with the matrix to the detector, whereas these are separated in time in the disc immunosensor system. © 2003 Elsevier B.V. All rights reserved.

"Developments Toward A Microfluidic System For Long-Term Monitoring Of Dynamic Cellular Events In Immobilized Human Cells"
Anal. Chem. 2004 Volume 76, Issue 16 Pages 4715-4720
Richard Davidsson, Åke Boketoft, Jesper Bristulf, Knut Kotarsky, Björn Olde, Christer Owman, Martin Bengtsson, Thomas Laurell and Jenny Emnéus

Abstract: A microfluidic system for long-term real-time monitoring of dynamic cellular events of immobilized human cells was investigated. The luciferase reporter gene activity in the reporter cell line HFF11, based on HeLa cells, was used as the model system. The cells were immobilized on silicon flow-through microchips and continuously supplied with a cell medium at 2 µL/min while maintaining the chip at 37°C. The HFF11 cell line was designed for high-throughput screening of ligands for seven-transmembrane receptors. When a ligand binds, the receptor is activated and a cascade of intracellular reactions starts, ending with the synthesis of the reporter protein Photinus luciferase. The major goal was to develop a microfluidic system for continuous long-term assaying of the intracellular reporter gene activity in real time and determine the conditions, which could minimize cells stress and hence unspecific expression of the reporter gene. In the resulting microfluidic system and assay protocol, the cell microchip could be kept and assayed for a period up to 30 h. The developed system and data outcome was compared with a corresponding microtiter plate performed with the same cell line to highlight the advantages obtained in the microfluidic format.

"Immunologic Trapping In Supported Liquid Membrane Extraction"
Anal. Chem. 2000 Volume 72, Issue 21 Pages 5280-5284
Eddie Thordarson, Jan Åke Jönsson, and Jenny Emnéus

Abstract: To obtain a high degree of selectivity in sample preparation, supported liquid membrane (SLM) extraction was combined with immunologic recognition, The SLM employs a hydrophobic polymer for supporting the immobilization of an organic solvent, thus forming a nonporous membrane. Said membrane separates the aqueous sample on one side (donor) from a receiving aqueous phase on the other (acceptor), The extraction involves the partitioning of neutral compounds between the sample solution, continuously pumped alongside the membrane, and the membrane. From the membrane, re-extraction takes place into a second aqueous phase containing antibodies specific for the target compound(s), Hence, there is a formation of an antibody-antigen complex at the heart of the sample preparation (ImmunoSLM). When the immunocomplex: forms, the antigen can no longer redissolve in the organic membrane, thus being trapped in the acceptor. Consequently, the concentration gradient of free antigen over the membrane is ideally unaffected, this being the driving force for the process. With a surplus of antibody, the concentration of analyte in the receiving phase will easily exceed the initial sample concentration. In this work, the so formed immunocomplex was quantified on-line, using a fluorescein flow immunoassay in a sequential injection analysis (SIA) setup, The outlined ImmunoSLM-SIA scheme was successfully applied for the extraction of 4-nitrophenol from spiked water solutions as well as from a spiked wastewater sample, indicating that the immunoextraction can be suitable when dealing with difficult matrixes.

"Specific Detection Of Image-glutamate In Food Using Flow-injection Analysis And Enzymatic Recycling Of Substrate"
Anal. Chim. Acta 2004 Volume 518, Issue 1-2 Pages 127-135
W. Khampha, J. Yakovleva, D. Isarangkul, S. Wiyakrutta, V. Meevootisom and J. Emnéus

Abstract: A flow injection analysis (FIA) system for specific determination of -glutamate in food samples based on a bi-enzymatic amplification system has been developed. The content of -glutamate in the sample was amplified by cycling between -glutamate dehydrogenase (GlDH) and a novel enzyme, -phenylglycine aminotransferase (-PhgAT). In this system, GlDH converts -glutamate to 2-oxoglutarate with concomitant reduction of NAD+ to NADH. -PhgAT transfers an amino group from -4-hydroxyphenylglycine to 2-oxoglutarate, thus recycling -glutamate. Accumulation of NADH in the course of the enzymatic recycling was monitored both by fluorescence and UV absorbance and used for quantification of -glutamate. The assay was characterized by high long-term stability (at least 70 days) and good reproducibility (within-day and between-day RSDs were 4.3-7.3% and 8.9%). The fluorimetric assay was slightly more sensitive with a -glutamate detection limit of 0.4 µM and linear range of 2.5-50 µM. The assay was specific for -glutamate, with recoveries between 95-103% in the presence of 17 different amino acids tested one by one. The method was applied to analysis of real food samples and results were correlated with a commercial Boehringer Mannheim assay kit.

"Enzyme Flow Immunoassay Using A Protein G Column For The Screening Of Triazine Herbicides In Surface And Waste Water"
Anal. Chim. Acta 2001 Volume 426, Issue 2 Pages 197-207
Bjarni Bjarnason, Luke Chimuka, Patrik Önnerfjord, Sergei Eremin, Jan-Åke Jönsson, Gillis Johansson and Jenny Emnéus

Abstract: A method for screening of triazine herbicides in surface and waste water is presented. The method is based on an enzyme flow immunoassay (EFIA) for the detection of the free fraction of a horse radish peroxidase (HRP)-labelled antigen (tracer). This was accomplished by trapping the bound tracer fraction in a Protein G column, allowing the residual free tracer fraction to pass and be detected spectrophotometrically after incubation with an enzyme substrate. As compared with detecting the bound tracer fraction this reduces the regeneration requirements of the Protein G column used for capturing the bound fraction and, therefore, reduces assay time. A polyclonal antibody directed against simazine showed no reactivity towards tracers that were thiopropionic acid derivatives of atrazine, simazine and terbutylazine. It had good sensitivity towards tracers using derivatives of 2-chloro-4,6-(alkylamino)-s-triazines such as atrazine and simazine. The highest sensitivity was obtained with an Et/Cl/N-C5-HRP tracer because this tracer could be used in combination with the lowest concentration of antibody. The detection limit was 0.1 µg L-1 with a linear range between 0.1 and 10 µg L-1 and an assay throughput of 12 h-1. Natural water samples from various locations in Russia were analyzed for triazines and the results were compared with a previously developed fluorescein flow immunoassay for triazines. The results were further verified by supported liquid membrane (SLM) extraction combined with HPLC. The results show that the two immunoassays behave differently and that the sample matrix influences their performance, however, no false negative results were obtained. The possible reasons for the different results between the two immunoassays are discussed.

"Improved Stability And Altered Selectivity Of Tyrosinase Based Graphite Electrodes For Detection Of Phenolic Compounds"
Anal. Chim. Acta 1999 Volume 387, Issue 3 Pages 309-326
Catalin Nistor, Jenny Emnéus, Lo Gorton and Anton Ciucu

Abstract: The operational and storage stability of tyrosinase biosensors were investigated for different tyrosinase modified electrodes, i.e., plain bulk modified carbon paste electrodes (CPEs), surface modified by simple adsorption to solid graphite electrodes (SGEs), and surface modified by the immobilization in Eastman AQ, a poly ester-sulfonic acid cation exchanger, and Nafion, a perfluorinated-sulfonated ionomer, on the surface of both CP and SGEs, Factors such as the pH of immobilization, the enzyme loading, and the polymer concentration were investigated in regards to the influence on the sensitivity, the limit of detection (LOD), the sample throughput (STP), and the operational and storage stability. Both storage and operational stability were improved by immobilization of tyrosinase in either of the two polymer matrices. For 50 consecutive injections of 50 µM catechol, the response stayed the same for the optimal Eastman and Nafion modified CP and SGEs. After about 42 days 80% and 75% of the original response for the Eastman and Nafion modified tyrosinase electrodes remained, respectively, whereas the tyrosinase bulk-modified CPE and adsorbed tyrosinase SGEs had lost virtually 100% of the original response. The selectivity for nine phenolic compounds were investigated and found to change with the introduction of the polymer membrane. The detection of especially monophenols was improved probably due to their pre-concentration into the polymer membranes. The best performing biosensor in terms of sensitivity, LOD, STP, operational and storage stability was reached for one where tyrosinase was immobilized in Nafion, i.e., sensitivity: 11.51 nA µM, LOD: 0.015 µM catechol, and STP: 36 samples/h. The phenolic content, expressed as catechol equivalents was evaluated in six waste water effluents from tannery industries in Spain and Sweden. The operational stability after 90 consecutive injections of extremely contaminated waste waters showed that the Nafion sensor retained 70% of its initial response.
Selectivity

"Comparison Between Different Inorganic Supports For The Immobilization Of Amyloglucosidase And α-amylase To Be Used In Enzyme Reactors In Flow Injection Systems. 2. Hydrolysis Of Glycogen"
Anal. Chim. Acta 1993 Volume 276, Issue 2 Pages 319-328
Jenny Emnéus* and Lo Gorton

Abstract: As a continuation of the work described in Part I, the immobilization procedure for glucan 1,4-α-glucosidase was carried out with four different inorganic supports, and heat-stable α-amylase (Termamyl) was also immobilized on three supports. The highest immobilization efficiency and optimum activity (for the entry of glycogen) were obtained with controlled-pore glass (CPG) supports of pore size 170 and 729 Å, respectively, and for Termamyl with Micropil A and a CPG support of 1489 Å, respectively.
Glycogen Immobilized enzyme Controlled pore glass Optimization

"Comparison Between Different Inorganic Supports For The Immobilization Of Amyloglucosidase And α-amylase To Be Used In Enzyme Reactors In Flow Injection Systems. 1. Hydrolysis Of Maltose, Malto-oligosaccharides And Soluble Starch"
Anal. Chim. Acta 1993 Volume 276, Issue 2 Pages 303-318
Jenny Emnéus* and Lo Gorton

Abstract: Glucan 1,4-α-glucosidase was immobilized on 12 different inorganic supports by silanization with aminopropyltriethoxysilane (I) followed by glutaraldehyde activation; also, two of the alumina-based supports were treated with PEI before glutaraldehyde activation. The various packings were then packed in identical reactors (1 cm x 2 mm; 30 µL) and compared in respect of optimum pore size, surface area, immobilization efficiency and enzyme activity for the cited substrates. The highest immobilization efficiency was obtained with a controlled-pore glass with a pore size of 170 .angstrom., and the highest enzyme activity with Micropil A (pore size 300 .angstrom.; surface area 100 to 150 m2 g-1). Treatment of the alumina supports with I gave better results than did treatment with PEI.
Maltooligosaccharides Maltose Starch Immobilized enzyme Alumina Optimization Controlled pore glass

"A Capillary-based Amperometric Flow Immunoassay For 2,4,6-trichlorophenol"
Anal. Bioanal. Chem. 2003 Volume 375, Issue 1 Pages 125-132
Catalin Nistor and Jenny Emnéus

Abstract: This paper describes the development of two different capillary-based heterogeneous competitive flow immunoassay formats (capillary flow injection immunoassay (CFIIA) and capillary sequential injection immunoassay (CSIIA)) for the determination of 2,4,6-trichlorophenol (2,4,6-TCP). The assays are based on the competition between the analyte and an analyte derivative labelled with the enzyme β-galactosidase, for an anti-TCP antibody, followed by the injection of the mixture at equilibrium into a flow stream, where separation between the fractions bound and unbound to the antibody is performed in a glass capillary containing immobilized protein A. The antibody-tracer fraction retained inside the protein A capillary was measured by injection of 4-aminophenyl-β-D-galactoside (4-APG), followed by amperometric detection of the enzymatically generated 4-aminophenol (4-AP), leading to a negative correlation between the signal and the analyte concentration. The two immunoassay formats were compared in terms of sensitivity and speed, giving IC50 values of 1.41±0.03 and 1.64±0.07 µg L-1, detection limits of 0.2 and 0.4 µg L-1, and sample throughputs of 6 and 4 h-1 for the CFIIA and CSIIA system, respectively. The influence of different interfering chlorophenolic compounds in the assay was minor, with only one exception (i.e. 2,4-dichlorophenol). In addition, different water matrices were tested (surface, tap, and rain water), showing that the matrix influence was negligible, except for rainwater, which resulted in a 30% increase in sensitivity. As a conclusion, the assay is suitable for the fast screening of TCP present at low concentration levels in water samples.
2,4,6-Trichlorophenol Surface Rain Water Amperometry Immunoassay Interferences