| 1. |
- Mecklenburg, M., et al.
(författare)
-
Differentiation of human serum samples by surface plasmon resonance monitoring of the integral glycoprotein interaction with a lectin panel
- 2002
-
Ingår i: Analytica Chimica Acta. - 0003-2670 .- 1873-4324. ; 459:1, s. 25-31
-
Tidskriftsartikel (refereegranskat)abstract
- Bacterial infection and inflammation result in massive changes in serum glycoproteins. These changes were investigated by the interaction of the saccharide glycoprotein moiety with lectins. A panel of eight lectins (Canavalia ensiformis, Bandeiraea simplicifolia BS-I, Arachis hypogaea, Phytolacca americana, Phaseolus vulgaris, Artocarpus integrifolia, Triticum vulgaris and Pisum sativum) was used to differentiate human serum glycoproteins obtained from patients with various bacterial infections. Lectin functionalised sensing layers were created on gold-coated wafers and lectin-glycoprotein interactions were monitored by surface plasmon resonance. The interaction of the lectin panel with serum glycoproteins produces unique patterns. Principal component analysis (PCA) was used to analyse the patterns. The actual panel of eight lectins enabled discrimination between sera obtained from patients sick with bacterial infection and healthy patients. Extended lectin panels have the potential to distinguish between types of bacterial infection and identify specific disease state. © 2002 Elsevier Science B.V. All rights reserved.
|
|
| 2. |
- Adbo, Karina, et al.
(författare)
-
Study of the kinetics of enantioselective solid-phase extraction on Tröger’s base molecularly imprinted polymers
- 2001
-
Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 435:1, s. 115-120
-
Tidskriftsartikel (refereegranskat)abstract
- Molecularly imprinted polymers (MIPs) selective for Tröger’s base were designed and synthesised, and HPLC-chromatographic evaluation of polymer recognition characteristics was undertaken. Baseline separation of racemic Tröger’s base was readily achieved, and enantioseparation factors (α) of up to 4.8±0.2 were obtained. The high enantioselectivity demonstrated by these materials prompted their use to examine the kinetics and thermodynamics of individual enantiomers in a solid-phase extraction (SPE) process. Enantiomer-dependent differences in the rates and extent of adsorption were observed. Furthermore, the enantiomeric enrichment of racemates was demonstrated in batch studies.
|
|
| 3. |
- Allender, Chris J., et al.
(författare)
-
Preface
- 2001
-
Ingår i: Analytica Chimica Acta. - 0003-2670 .- 1873-4324. ; 435:1, s. 1-2
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
|
| 4. |
- Artursson, Tom, et al.
(författare)
-
Variable reduction on electronic tongue data
- 2002
-
Ingår i: Analytica Chimica Acta. - 0003-2670 .- 1873-4324. ; 452:2, s. 255-264
-
Tidskriftsartikel (refereegranskat)abstract
- Reduction of the number of variables in data from a so-called electronic tongue contributes to simpler model calculations and less storage requirements. In this study, we have developed a model for this purpose. This model describes the response from the electrodes in the electronic tongue with two exponential functions plus a constant term, i(t) = k + kf e-ta + kc e-tß, where t is the time. From the model, five parameters which describe the signal are extracted. These parameters can be used as inputs instead of the original signal to any multivariate algorithm. The results show that the variables obtained are at least as good as the original data to separate between different classes, even though the number of parameters has been reduced between 80 and 199 times. © 2002 Elsevier Science B.V. All rights reserved.
|
|
| 5. |
- Dahlqvist, Ralf, et al.
(författare)
-
Performance of the diffusive gradients in thin films technique for measuring Ca and Mg in freshwater
- 2002
-
Ingår i: Analytica Chimica Acta. - 0003-2670 .- 1873-4324. ; 460:2
-
Tidskriftsartikel (refereegranskat)abstract
- Measurements of the major cations Ca and Mg by the technique of diffusive gradients in thin films (DGTs) were systematically evaluated. The concentration in solution was calculated using Fick's first law of diffusion from the directly measured flux to the DGT device. A selective cation exchange resin (Bio-Rad Chelex®100), which has been used extensively with DGT for trace metals, such as Cd2+, Cu2+ and Ni2+, was used for this work. Elution of Ca and Mg from the resin with 1 M HNO3 was very reproducible. Measurements of Ca and Mg concentrations in synthetic solutions agreed well with the theoretical predictions. The negative response on uptake caused by lowered pH was investigated. Uptake was found to decline below pH 5. The capacity of the DGT device for Ca and Mg was also investigated to establish maximum deployment times for given concentrations. Experiments with filtered and modified lake water show that DGT can be used to measure Ca and Mg when trace metals are present in the solution. An in situ deployment of DGT combined with an ultrafiltration study suggest that the Mg concentration measured by DGT is similar to the concentration found in the fraction <1 kDa.
|
|
| 6. |
- Ivansson, D., et al.
(författare)
-
Quantitation of intracellular recombinant human superoxide dismutase using surface plasmon resonance
- 2002
-
Ingår i: Analytica Chimica Acta. - 0003-2670 .- 1873-4324. ; 456:2, s. 193-200
-
Tidskriftsartikel (refereegranskat)abstract
- An immunosensor assay for the quantitation of intracellular recombinant human superoxide dismutase (rhSOD) in Escherichia coli cultivations based on detection with surface plasmon resoance (SPR) is described. A monoclonal antibody for rhSOD was immobilized on a SPR dextran gold chip. Bacterial samples were sonicated and centrifugated prior to injection over the antibody chip for SPR detection. The assay time was 7min and allowed quantitation in the range of 1-64nM SOD in lysate samples with a precision of 1.1-3.4%. The assay was applied to monitor the concentration of rhSOD during E. coli bioreactor cultivations where the rhSOD production was induced by iso-propyl-b-D-thiogalactoside (IPTG). The assay allowed accurate monitoring of the production of rhSOD where the important phases in the product formation were possible to see. The report also discusses influence from sample preparation, SPR selectivity and sensitivity and quantitation limits. The assay proved to be fast, sensitive and accurate with low background effects from the dextran matrix of the SPR chip. ⌐ 2002 Published by Elsevier Science B.V.
|
|
| 7. |
- Ivarsson, Patrik, et al.
(författare)
-
Comparison of a voltammetric electronic tongue and a lipid membrane taste sensor
- 2001
-
Ingår i: Analytica Chimica Acta. - 0003-2670 .- 1873-4324. ; 449:1-2, s. 59-68
-
Tidskriftsartikel (refereegranskat)abstract
- An electronic tongue based on voltammetry and a multichannel lipid membrane taste sensor based on potentiometry are compared using two aqueous examples: detergents and teas. The electronic tongue consists of four electrodes of different metals, a reference electrode and a counter electrode. The measurement principle is based on pulse voltammetry in which current is measured during the change of the amplitude of the applied potential. The taste sensor is based on eight different lipid/polymer membranes. The voltage difference between the electrodes and an Ag/AgCl reference electrode is measured when the current is close to zero. The responses from the two sensors systems are treated separately with multivariate data analysis based on principal component analysis and then merged to examine if further information could be extracted. It is shown that although the two sensor systems are about equal in separation ability in the two cases, extra information can be gained by combination of the two sensor systems. © 2001 Elsevier Science B.V. All rights reserved.
|
|
| 8. |
- Jonsson, Tobias, et al.
(författare)
-
Heterocyclic compounds as catalysts in the peroxyoxalate chemiluminescence reaction of bis(2,4,6-trichlorophenyl)oxalate
- 1998
-
Ingår i: Analytica Chimica Acta. - Amsterdam : Elsevier. - 0003-2670 .- 1873-4324. ; 361:3, s. 205-215
-
Tidskriftsartikel (refereegranskat)abstract
- Substituted imidazoles and leaving groups known from other areas of chemistry have been tested for catalytic efficiency in the peroxyoxalate chemiluminescence (PO-CL) reaction, using bis(2,4,6-trichlorophenyl)oxalate (TCPO) as reagent. Catalytic activity was found for 1,2,4-triazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole and 4,5-dichloroimidazole, while 2-mercaptoimidazole, 2-nitroimidazole, 4-nitroimidazole, benzimidazole, benzotriazole, thiazole, o-benzoic sulfimide, phthalimide, succinimide, 2(1H)-pyridone and 1,2,3-benzotriazine-4(3H)-one yielded no detectable chemiluminescence under the conditions used. None of the tested compounds was more efficient than imidazole in catalyzing the PO-CL reaction. Spectrophotometric measurements of the catalytic breakdown of TCPO showed that an intermediate was formed with almost all catalysts, and that intermediates that were more stable or present at lower concentration led to a reduced catalytic efficiency in the PO-CL reaction of TCPO.
|
|
| 9. |
- Jonsson, Tobias, et al.
(författare)
-
Very fast peroxyoxalate chemiluminescence
- 1999
-
Ingår i: Analytica Chimica Acta. - Amsterdam : Elsevier. - 0003-2670 .- 1873-4324. ; 400:1-3, s. 257-264
-
Tidskriftsartikel (refereegranskat)abstract
- Peroxyoxalate chemiluminescence (PO-CL) detection offers an advantage in chromatographic detection, by the virtue of its multiple unique selectivities and high sensitivity. However, many of the analytical separation techniques available today require observation times in the millisecond range to preserve the band resolution, and as the reaction kinetics of the PO-CL reaction is considerably slower, extra flow elements are needed to observe the reaction in a time window at maximum emission intensity. Since these flow elements increase the complexity of the system and contribute to band-broadening, the rational way to adapt PO-CL detection to miniaturised separation systems is to speed up the reaction, so that it emits an initial burst of light within the acceptable detection time-frame. Although this may result in a lower overall quantum yield, the actual detection sensitivity could be equal to, or better than slower PO-CL systems. By making careful selections of oxalic reagent and catalyst(s) the reaction can be fine-tuned to maximise the intensity. In this work, the time-dependent light emission from the reaction of bis(2,4,6-trichlorophenyl)oxalate (TCPO) was studied under the catalytic influence of imidazole, 1,2,4-triazole, 4-dimethylaminopyridine (DMAP), and 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) in acetonitrile. Both DMAP and DBU accelerated the reaction substantially, but the best combination of reaction speed and intensity was found for a mixture of 0.5 mM DBU and 5 mM 1,2,4-triazole, which reached its maximum emission after only 40 ms and had an emission intensity comparable to that seen with 5 mM imidazole as catalyst.
|
|
| 10. |
- Jungar, Christina, et al.
(författare)
-
Neoglycoconjugates as affinity ligands in surface plasmon resonance analysis
- 2001
-
Ingår i: Analytica Chimica Acta. - 0003-2670 .- 1873-4324. ; 449:1-2, s. 51-58
-
Tidskriftsartikel (refereegranskat)abstract
- Neoglycoconjugates, i.e. de novo synthesized conjugates of glycosides and carrier molecules such as proteins or polylipids, were used as affinity ligands in a surface plasmon resonance (SPR) biosensor assay. The affinity of the glycoconjugates, normally in the lower affinity range, was influenced by increasing the number of glycosides bound per carrier protein, the coupling chemistry, and the assay temperature. As a model system, albumin-conjugated A- and B-active blood group oligosaccharides with suitable linker molecules were chosen. Specific monoclonal antibodies were used as analytes to verify the interactive performance. Affinity kinetics of the systems were evaluated from the SPR biosensor data. The results demonstrate that neoglycoconjugates are a good alternative in presenting affinity ligands of small, specific molecules in SPR-based assays with retained specificity and bioavailability. ⌐ 2001 Elsevier Science B.V. All rights reserved.
|
|
