| 1. |
- Lard, Mercy, et al.
(författare)
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Tracking the small with the smallest--using nanotechnology in tracking zooplankton.
- 2010
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 5:10
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Tidskriftsartikel (refereegranskat)abstract
- A major problem when studying behavior and migration of small organisms is that many of the questions addressed for larger animals are not possible to formulate due to constraints on tracking smaller animals. In aquatic ecosystems, this problem is particularly problematic for zoo- and phytoplankton, since tracking devices are too heavy to allow the organism to act naturally. However, recent advances in nanotechnology have made it possible to track individual animals and thereby to focus on important and urgent questions which previously have not been possible to address. Here we report on a novel approach to track movement and migratory behavior of millimeter sized aquatic animals, particularly Daphnia magna, using the commercially available nanometer sized fluorescent probes known as quantum dots. Experimental trials with and without quantum dots showed that they did not affect behavior, reproduction or mortality of the tested animals. Compared to previously used methods to label small animals, the nano-labeling method presented here offers considerable improvements including: 24 h fluorescence, studies in both light and darkness, much improved optical properties, potential to study large volumes and even track animals in semi-natural conditions. Hence, the suggested method, developed in close cooperation between biologists, chemists and physicists, offers new opportunities to routinely study zooplankton responses to light, food and predation, opening up advancements within research areas such as diel vertical/horizontal migration, partial migration and other differences in intra- and interspecific movements and migration.
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| 2. |
- Nahálková, Jarmila, et al.
(författare)
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Affinity analysis of lectin interaction with immobilized C- and O-gylcosides studied by surface plasmon resonance assay
- 2002
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Ingår i: Journal of Biochemical and Biophysical Methods. - 0165-022X .- 1872-857X. ; 52:1, s. 11-18
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Tidskriftsartikel (refereegranskat)abstract
- A biosensor based on the surface plasmon resonance (SPR) principle was used for kinetic analysis of lectin interactions with different immobilized saccharide structures. A novel affinity ligands beta-D-glycopyranosylmethylamines derived from common D-aldohexoses linked to the carboxymethyl dextran layer of the SPR sensor surface served for interactions with a wide range of lectins. The method of preparation and use of the beta-D-mannopyranosyl glycosylated sensor surface was described. The results of affinity analysis of lectin-ligand interactions were evaluated and compared with data obtained from measurements using commercially available p-aminophenyl alpha-D-glycopyranosides. Possible applications and advantages of C- and O-glycosylated SPR biosensors are discussed.
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| 3. |
- Yakovleva, Maria, et al.
(författare)
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A novel combined thermometric and amperometric biosensor for lactose determination based on immobilised cellobiose dehydrogenase.
- 2012
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Ingår i: Biosensors & Bioelectronics. - : Elsevier BV. - 1873-4235 .- 0956-5663. ; 31, s. 251-256
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Tidskriftsartikel (refereegranskat)abstract
- A novel method for lactose determination in milk is proposed. It is based on oxidation of lactose by cellobiose dehydrogenase (CDH) from the basidiomycete Phanerochaete chrysosporium, immobilised in an enzyme reactor. The reactor was prepared by cross-linking CDH onto aminopropyl-silanised controlled pore glass (CPG) beads using glutaraldehyde. The combined biosensor worked in flow injection analysis (FIA) mode and was developed for simultaneous monitoring of the thermometric signal associated with the enzymatic oxidation of lactose using p-benzoquinone as electron acceptor and the electrochemically generated current associated with the oxidation of the hydroquinone formed. A highly reproducible linear response for lactose was obtained between 0.05mM and 30mM. For a set of more than 500 samples an R.S.D. of less than 10% was achieved. The assay time was ca. 2min per sample. The sensor was applied for the determination of lactose in dairy milk samples (milk with a fat content of 1.5% or 3% and also "lactose free" milk). No sample preparation except dilution with buffer was needed. The proposed method is rapid, suitable for repeated use and allows the possibility to compare results from two different detection methods, thus providing a built-in quality assurance. Some differences in the response observed between the methods indicate that the dual approach can be useful in mechanistic studies of redox enzymes. In addition, a dual system opens up interesting possibilities for studies of enzyme properties and mechanisms.
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| 4. |
- Asif, Muhammad H, et al.
(författare)
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Functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose
- 2010
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Ingår i: Biosensors & Bioelectronics. - : Elsevier BV. - 1873-4235 .- 0956-5663. ; 25:10, s. 2205-2211
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we report a functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose. To adjust the sensor for intracellular glucose measurements, we grew hexagonal ZnO nanorods on the tip of a silver-covered borosilicate glass capillary (0.7 mu m diameter) and coated them with the enzyme glucose oxidase. The enzyme-coated ZnO nanorods exhibited a glucose-dependent electrochemical potential difference versus an Ag/AgCl reference microelectrode. The potential difference was linear over the concentration range of interest (0.5-1000 mu M). The measured glucose concentration in human adipocytes or frog oocytes using our ZnO-nanorod sensor was consistent with values of glucose concentration reported in the literature; furthermore, the sensor was able to show that insulin increased the intracellular glucose concentration. This nanoelectrode device demonstrates a simple technique to measure intracellular glucose concentration. (C) 2010 Elsevier B.V. All rights reserved.
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| 5. |
- Asif, Muhammad, 1978-, et al.
(författare)
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Selective calcium ion detection with functionalized ZnO nanorods-extendedgate MOSFET
- 2009
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Ingår i: Biosensors & bioelectronics. - : ELSEVIER. - 0956-5663 .- 1873-4235. ; 24:11, s. 3379-3382
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Tidskriftsartikel (refereegranskat)abstract
- Zinc oxide nanorod-extended gate field effect transistor (MOSFET) is demonstrated for the detection of calcium (Ca2+) ions. ZnO nanorods were grown on the surface of a silver wire to produce an electrochemical nanosensor for selectively detecting Ca2+. The electrochemical response from the interaction between the ZnO nanorods and Ca2+ in an aqueous solution is coupled directly to the gate of a field effect transistor (MOSFET). The induced voltage change on the gate results in a measureable current response. In order to adapt the sensors for Ca2+ ions measurements in biological fluids with sufficient selectivity and stability, a plastic membrane coating containing ionophores was applied on the nanorods. The sensor exhibited a linear response within the range of interest from 1 μM to 1 mM. This work demonstrates a simple technique for sensitive detection of Ca2+ ions by efficient transfer of the chemical response directly to a standard electronic component producing a low impedance signal.
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| 6. |
- Bhand, Sunil, et al.
(författare)
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Coupled biosensor, biomimetic and chemometrics strategies for analysis of the metals in complex environmental matrices
- 2003
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Ingår i: Journal de Physique IV - Proceedings. - : EDP Sciences. - 1764-7177 .- 1155-4339. ; 107, s. 169-172
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Konferensbidrag (refereegranskat)abstract
- An analytical strategy to determine metals in environmental samples contaminated with both organophosphate pesticides and metals is presented. In the first step, parathion and arsenate were determined separately. Inhibition of the enzyme butyrylcholinesterase was quantified employing an enzyme thermistor and also with a CCD camera. Subsequently, parathion mixed with arsenate was measured. A molecularly imprinted polymer catalyst was then introduced as a pre-column to degrade OPs. The catalytic MIP enabled the measurement of metal from the mixture containing OPs. Hydrolysis of parathion, ethyl paraoxon, O-Ethyl-O-(4-nitrophenyl)-phenylphosphonothioate EPN and dichlorvos were monitored by using catalytic MIPs in the enzyme thermistor. Finally, inhibition patterns of parathion and arsenate were obtained employing multivariate analysis. The patterns generated after eliminating the OPs can be used for monitoring and mapping of metals in various environmental matrices.
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| 7. |
- Bhand, Sunil, et al.
(författare)
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Immuno-arrays for multianalyte analysis of chlorotriazines
- 2005
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Ingår i: Talanta. - : Elsevier BV. - 1873-3573 .- 0039-9140. ; 65:2, s. 331-336
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a novel strategy for multicomponent analysis of two classes of pesticides such as triazines (atrazine and simazine) and phenoxyalkanoic acids (2,4-dichlorophenoxy acetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), 4-chlorophenoxyacetic acid (CPOAc), phenoxyacetic acid (POAc)) employing immuno-arrays is demonstrated. The approach is based on cross-reactive arrays of specific antibody pairs coupled to chemometric pattern recognition. The monoclonal antibody pairs employed in this work (atrazine–simazine and 2,4-D) are specific towards a set of analytes and preclude a particular set of others present in the sample matrix. Antibody pairs of atrazine, simazine, and 2,4-D are used to discriminate and quantify analyte of interest. Atrazine was quantified in presence of trace concentration of simazine and that of 2,4-D. The combinatorial cross-reactivity of antibody pairs towards simazine, atrazine and 2,4-D is used to distinguish among different classes of analytes and their influence on the signal suppression in immuno-techniques. These sensors exclude recognition by carbamates such as carbaryl and carbofuran.
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| 8. |
- da Cruz Francisco, José, et al.
(författare)
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Application of supercritical carbon dioxide for the extraction of alkylresorcinols from rye bran
- 2005
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Ingår i: Journal of Supercritical Fluids. - : Elsevier BV. - 0896-8446. ; 35:3, s. 220-226
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Tidskriftsartikel (refereegranskat)abstract
- The use of supercritical CO, (SC-CO2) for extracting alkylresorcinols from rye bran was investigated. For pure SC-CO2, 35 MPa and 55 degrees C were used. SC-CO2 with 10% ethanol or methanol as co-solvents was tested at four pressure levels (8, 15, 30 and 35 MPa) and two temperatures (40 and 55 degrees C). Experiments were conducted at a constant SC-CO2 flow of 5 g/min for 2 h. For comparative purposes acetone at ambient temperature and pressure was also used for extraction. The best extractions were achieved when SC-CO2 was used with co-solvents. At 55 degrees C and 15-30 MPa, the use Of SC-CO2 with co-solvents has yielded from 8 to 80% (w/w) more extracted product than acetone. Yield of extracts was proportional to pressure (when above 30 MPa) and temperature. The results suggest that cleaner bran extracts can be obtained by using pure SC-CO2 followed by the addition of co-solvents. There is no clear advantage of using either methanol or ethanol. (c) 2005 Elsevier B.V. All rights reserved.
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| 9. |
- da Cruz Francisco, José, et al.
(författare)
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Isolation of alkylresorcinols: Classical and supercritical CO2 extraction methods
- 2006
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Ingår i: Modern Extraction Techniques: Food and Agricultural Samples (ACS Symposium). - 0097-6156. - 9780841239401 - 0841239401 ; 926, s. 51-61
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter focuses on the use of different methods for isolation of alkylresorcinols. Alkylresorcinols are members of a lipid group called non-isoprenoid phenolic lipids. Different aspects of the extraction by classical methods and supercritical CO2 are discussed. Supercritical CO2 extraction of alkylresorcinols from rye bran is discussed for the first time. As compared to the classical extraction methods, supercritical CO2 gives higher yields and it allows the separation of the crude extrac into long- and short-chain alkylresorcinol homologues.
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| 10. |
- Danielsson, Bengt
(författare)
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Artificial receptors
- 2008
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Ingår i: Biosensing for the 21st Century (Advances in Biochemical Engineering/Biotechnology). - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0724-6145. - 9783540752004 ; 109, s. 97-122
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Herein I will provide a brief overview of artificial receptors with emphasis on molecularly imprinted polymers (MIPs) and their applications. Alternative techniques to produce artificial receptors such as in silico designed and modelled polymers as well as different receptors designed using libraries of more or less natural composition will also be mentioned. Examples of these include aptamers and bio-nanocomposites. The physical presentation of the receptors is important and may depend on the application. Block polymerization of MIPs and grinding to particles of suitable size used to be the preferred technique, but today beaded materials can be produced in sizes down to nanobeads and also nanofibers can be used to increase available surface area and thereby capacity. For sensor applications it may be attractive to include the artificial receptors in surface coatings or in membrane structures. Different composite designs can be used to provide additional desirable properties. MIPs and other artificial receptors are gaining rapidly increasing attention in very shifting application areas and an attempt to provide a systematic account for current applications has been made with examples from separation, solid-phase extraction, analysis, carbohydrate specific experiments, and MIPs-directed synthesis.
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