| 1. |
- Bossi, A, et al.
(författare)
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An assay for ascorbic acid based on polyaniline-coated microplates
- 2000
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Ingår i: Analytical Chemistry. - : ACS American Chemical Society. - 0003-2700 .- 1520-6882. ; 72:18, s. 4296-4300
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Tidskriftsartikel (refereegranskat)abstract
- A technique for modification of the microtiter reader plates well with a polyaniline (PANI) film sensitive for ascorbic acid is presented. The principle of the analyte detection is based on monitoring the changes in optical absorption of the PANI film resulting from the reduction process initiated by ascorbic acid. The detection limit for ascorbic acid is 1 mg/L. Testing with real samples (soft drinks, fruit juices) gave good correlation of the method with iodimetric titration. High sensitivity, stability, and good reproducibility of the measurements make the proposed system an attractive alternative to traditional assays, used in medicine, ecology and biotechnology.
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| 2. |
- Bossi, A, et al.
(författare)
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Capillary electrophoresis coupled to biosensor detection
- 2000
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Ingår i: Journal of Chromatography A. - : Elsevier Science B.V., Amsterdam.. - 0021-9673 .- 1873-3778. ; 892:02-jan, s. 143-153
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Tidskriftsartikel (refereegranskat)abstract
- The present review highlights some modern aspects of biosensor revelation, a detection method which has already found a large number of applications in healthcare, food industry and environmental analysis. First, the concept of bio-recognition, which is at the heart of biosensor technology, is discussed, with emphasis on host-guest-like recognition mechanisms. This detection device has been successfully coupled, in its first applications, to chromatographic columns, which allow a high resolution of complex mixtures of analytes prior to interaction with the biosensing unit. The properties of the transducing elements, which should generate a signal (e.g., electrochemical, thermal, acoustic, optical) of proper intensity and of relative fast rise, are additionally evaluated and discussed. The review then focuses on potential applications of biosensing units in capillary electrophoresis (CE) devices. CE appears to be an excellent separation methodology to be coupled to biosensor detection, since it is based on miniaturized electrophoretic chambers, fast analysis times, complete automation in sample handling and data treatment and requires extremely small sample volumes. Although only a few applications of CE-based biosensors have been described up to the present, it is anticipated that this hyphenated technique could have a considerable expansion in the coming years, (C) 2000 Elsevier Science B.V. All rights reserved.
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| 3. |
- Bossi, A, et al.
(författare)
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Repartition effect of aromatic polyaniline coatings on the separation of bioactive peptides in capillary electrophoresis
- 2002
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Ingår i: Electrophoresis. - : John Wiley andamp;amp; Sons, Ltd. - 0173-0835 .- 1522-2683. ; 23:2, s. 203-208
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Tidskriftsartikel (refereegranskat)abstract
- The capillary walls of fused-silica capillary electrophoresis (CE) columns were modified with a thin film of polyaniline (PANI), providing open-tubular columns with a stable coating containing aromatic groups and amine functionalities. Fast and efficient separations were observed for small bioactive peptides under acidic conditions on PANI-coated columns. The mechanism of separation is based on hydrophobic interactions between the analytes and the polymeric matrix. Good reproducibility was observed from run-to-run. Due to the simple derivatization procedure, method flexibility, the uniformity of the coating and its stability, conjugated polymers could find practical application in capillary zone electrophoresis (CZE) separations.
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| 4. |
- Bossi, A, et al.
(författare)
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Surface-grafted molecularly imprinted polymers for protein recognition
- 2001
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Ingår i: Analytical Chemistry. - : ACS American Chemical Society. - 0003-2700 .- 1520-6882. ; 73:21, s. 5281-5286
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Tidskriftsartikel (refereegranskat)abstract
- A technique for coating microplate wells with molecularly imprinted polymers (MIPs) specific for proteins is presented. 3-Aminophenylboronic acid was polymerized in the presence of the following templates: microperoxidase, horseradish peroxidase, lactoperoxidase, and hemoglobin, via oxidation of the monomer by ammonium persulfate. This process resulted in the grafting of a thin polymer layer to the polystyrene surface of the microplates. Imprinting resulted in an increased affinity of the polymer toward the corresponding templates. The influence of the washing procedure, template concentration, and buffer pH on the polymer affinity was analyzed. It was shown that the stabilizing function of the support and spatial orientation of the polymer chains and template functional groups are the major factors affecting the imprint formation and template recognition. Easy preparation of the MIPs, their high stability, and their ability to recognize small and large proteins, as well as to discriminate molecules with small variations in charge, make this approach attractive and broadly applicable in biotechnology, assays and sensors.
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| 5. |
- Bossi, A, et al.
(författare)
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Towards the development of an integrated capillary electrophoresis optical biosensor
- 2003
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Ingår i: Electrophoresis. - : John Wiley andamp;amp; Sons, Ltd. - 0173-0835 .- 1522-2683. ; 24:19-20, s. 3356-3363
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Tidskriftsartikel (refereegranskat)abstract
- Extending the previous preliminary study on the construction of a capillary electrophoresis (CE)/sensor for the detection of reducing analytes, we focus the interest on the simultaneous detection of redox active species, which are important indicators of the oxidative damage in tissues, of food preservation, and of pollution. The CE/sensor was built by modifying the detector-portion of the capillary with the redox-sensitive polymer polyaniline (PANI). The analyte is detected by monitoring the changes in optical absorption of the PANI film. The CE/sensor was tested, with good results, with ascorbic acid, glutathione (GSH), as well as with compounds with very close similarity (ascorbic and isoascorbic acid). The kinetics of oxidation and reduction of PANI were evaluated. Further a PANI/CE-biological sensor was developed by coupling an enzyme, glucose oxidase (GOD), to the PANI-modified portion of the capillary. The stability of the immobilized GOD and the sensitivity of the CE/biosensor were studied, by using glucose as test analyte in concentrations within the physiological range. The results indicate that the CE/biosensor had good stability (more than 75% of original activity retained after 30 operational days), manufacturing reproducibility and a sensing range convenient for monitoring physiological glucose (1-24 mm).
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| 6. |
- Castelletti, L, et al.
(författare)
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Development of an integrated capillary electrophoresis/sensor for L-ascorbic acid detection
- 2002
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Ingår i: Electrophoresis. - : John Wiley andamp;amp; Sons, Ltd. - 0173-0835 .- 1522-2683. ; 23:2, s. 209-214
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Tidskriftsartikel (refereegranskat)abstract
- A CE/biosensor for measuring ascorbic acid was developed by coupling a polyaniline optical sensor and capillary electrophoresis (CE). The capillary column was partially modified with a thin film of polyaniline redox sensitive material. Ascorbic acid was detected by monitoring the changes in optical absorbance occurring to the polyaniline film upon the reduction reaction. The sensor response (change in optical absorbance at 650 nm) is proportional to the concentration of ascorbic acid over a range of 2.5-250 mg/L and the response range has shown a clear dependence on the characteristics of the polymerized film. High specificity and sensitivity of the present method, low sample consumption, short times of response (ca. 2 min) and the reproducibility of the results demonstrate that the CE/polyaniline-sensor could be further employed in the study of the relation between the content of L-ascorbic acid in body fluids and clinical parameters, e.g., cell ageing.
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| 7. |
- Chen, BN, et al.
(författare)
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Molecular recognition: Design of "keys"
- 2002
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Ingår i: Combinatorial chemistry & high throughput screening. - : Bantham Science Publishers Ltd. - 1386-2073 .- 1875-5402. ; 5:6, s. 409-427
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Forskningsöversikt (refereegranskat)abstract
- Molecular recognition between molecules is one of the most fundamental processes in biology and chemistry. The recognition process is largely driven by non-covalent forces such as hydrogen bonding, electrostatics, van der Waals forces, pi-pi interactions, and conformational energy. The complementarity between the receptor and substrate is very similar to the "lock and key" function, first described by Emil Fischer over 100 years ago, - the lock being the molecular receptor such as a protein or enzyme and the key being the substrate such as a drug, that is recognized to give a defined receptor-substrate complex. This review focuses on the design of specific ligand systems as "Keys" to enable the induced fit of these keys into the target macromolecules, protein/enzyme (Locks) with particular emphasis on protein recognition.
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| 8. |
- Chianella, I, et al.
(författare)
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MIP-based solid phase extraction cartridges combined with MIP-based sensors for the detection of microcystin-LR
- 2003
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Ingår i: Biosensors & bioelectronics. - : Elsevier Science B.V., Amsterdam.. - 0956-5663 .- 1873-4235. ; 18:03-feb, s. 119-127
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Tidskriftsartikel (refereegranskat)abstract
- Microsystin-LR is one of the most widespread and dangerous toxins produced by the freshwater Cyanobacteria. The contamination of water supplies with microcystin-LR has been reported in several areas around the world and the development of an easy-to-use, rapid, robust and inexpensive sensor for this toxin is urgently required. In this work an artificial receptor for microcystin-LR was synthesised using the technique of molecular imprinting. The composition of the molecularly imprinted polymer (MIP) was optimised using computer modelling. The synthesised polymer was used both as a material for solid-phase extraction (SPE) and as a sensing element in a piezoelectric sensor. Using the combination of SPE followed by detection with a piezoelectric sensor the minimum detectable amount of toxin was 0.35 nM. The use of MIP-SPE provided up to 1000 fold preconcentration, which was more than sufficient for achieving the required detection limit for microcystin-LR in drinking water (I nM). This work is the first example where the same MIP receptor has been used successfully for both SPE and the corresponding sensor. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 9. |
- Chianella, I, et al.
(författare)
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Rational design of a polymer specific for microcystin-LR using a computational approach
- 2002
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Ingår i: Analytical Chemistry. - : ACS American Chemical Society. - 0003-2700 .- 1520-6882. ; 74:6, s. 1288-1293
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Tidskriftsartikel (refereegranskat)abstract
- A computational approach for the design of a molecularly imprinted polymer (MIP) specific for Cyanobacterial toxin microcystin-LR is presented. By using molecular modeling software, a virtual library of functional monomers was designed and screened against the target toxin, employed as a template. The monomers giving the highest binding energy were selected and used in a simulated annealing (molecular dynamics) process to investigate their interaction with the template. The stoichiomettic ratio observed from the simulated annealing study was used in MIP preparation for microcystin-LR. The monomers were copolymerized with a cross-linker in the presence of the template. A control (blank) polymer was prepared under the same conditions but in the absence of template. A competitive assay with microcystin-horseradish peroxidase conjugate was optimized and used to evaluate the affinity and cross-reactivity of the polymer. The performance of the artificial receptor was compared to the performance of monoclonal and polyclonal antibodies raised against the toxin. The results indicate that imprinted polymer has affinity and sensitivity comparable to those of polyclonal antibodies (die detection limit for microcystin-LR using the MIP-based assay was found to be 0.1 mug L-1), while superior chemical and thermal stabilities were obtained. Moreover, cross-reactivity to other toxin analogues was very low for the imprinted polymer, in contrast to the results achieved for antibodies. It is anticipated that the polymer designed could be used in assays, sensors, and solid-phase extraction.
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| 10. |
- Kroger, S, et al.
(författare)
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Biosensors for marine pollution research, monitoring and control
- 2002
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Ingår i: Marine Pollution Bulletin. - : Elsevier Science B.V., Amsterdam.. - 0025-326X .- 1879-3363. ; 45:12-jan, s. 24-34
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Tidskriftsartikel (refereegranskat)abstract
- Measurement of ecological, climatic and anthropogenic changes underpins the formulation of effective management strategies for sustainable use and protection of the marine environment. Sensors are traditionally used in marine studies to determine physical parameters, but there is increasing demand for real-time information about chemical and biological parameters. These parameters are currently measured in samples collected at sea and subsequently analysed in the laboratory. Biosensors fuse the exquisite sensitivity and specificity of living systems with the processing power of microelectronics to deliver simple, inexpensive measurement systems for use in the field or deployment in situ. While their potential for use in the marine environment is enormous, much published work to date has focussed on applications in freshwater and wastewater. Marine applications pose a substantial challenge in the robustness required for remote application, but recent developments in portable medical devices and receptor design suggest that these demands can now be realistically tackled. (C) 2002 Elsevier Science Ltd. All rights reserved.
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