| 1. |
- Berti, Francesca, et al.
(author)
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One-Dimensional Polyaniline Nanotubes for Enhanced Chemical and Biochemical Sensing
- 2011
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In: Sensors and Microsystems. - Dordrecht : Springer Netherlands. - 9789400713239 ; , s. 311-315
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Book chapter (other academic/artistic)abstract
- In this work we explored a simple, cheap and fast route to grow polyaniline (PANI) nanotubes arranged in an ordered structure directly on an electrode surface by electrochemical polymerisation. The deposited nanostructures were electrochemically and morphologically characterised and then used as a functional substrate for biochemical sensing by combining the intrinsic advantages of nanostructures as optimal transducers and the well known benefits of molecularly imprinted polymers (MIPs) as receptors. The hybrid nanostructured-MIP sensor was applied to the molecular recognition of catechol. Moreover, a gas sensing application was also investigated by exploiting resistance variation of the polymer in presence of different gases (CO, NO2, NH3 and ethanol).
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| 2. |
- Berti, Francesca, et al.
(author)
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Quasi-monodimensional polyaniline nanostructures for enhanced molecularly imprinted polymer-based sensing
- 2010
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In: Biosensors & bioelectronics. - : Elsevier Science B.V., Amsterdam.. - 0956-5663 .- 1873-4235. ; 26:2, s. 497-503
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Journal article (peer-reviewed)abstract
- Recent advances in nanotechnology have allowed significant progress in utilising cutting-edge techniques associated with nanomaterials and nano-fabrication to expand the scope and capability of biosensors to a new level of novelty and functionality. The aim of this work was the development and characterisation of conductive polyaniline (PANI) nanostructures for applications in electrochemical biosensing. We explore a simple, inexpensive and fast route to grow PANI nanotubes, arranged in an ordered structure directly on an electrode surface, by electrochemical polymerisation using alumina nanoporous membranes as a nano-mould. The deposited nanostructures have been characterised electrochemically and morphologically prior to grafting with a molecularly imprinted polymer (MIP) receptor in order to create a model sensor for catechol detection. In this way, PANI nanostructures resulted in a conductive nanowire system which allowed direct electrical connection between the electrode and the synthetic receptor (MIP). To our knowledge, this is the first example of integration between molecularly imprinted polymers and PANI nanostructured electrodes. The advantages of using nanostructures in this particular biosensing application have been evaluated by comparing the analytical performance of the sensor with an analogous non-nanostructured MIP-sensor for catechol detection that was previously developed. A significantly lower limit of detection for catechol has been obtained (29 nM, one order of magnitude), thus demonstrating that the nanostructures are capable of improving the analytical performance of the sensor. (C) 2010 Elsevier B.V. All rights reserved.
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| 3. |
- Kyprianou, Dimitris, et al.
(author)
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New reactive polymer for protein immobilisation on sensor surfaces
- 2009
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In: Biosensors & bioelectronics. - : Elsevier Science B.V., Amsterdam.. - 0956-5663 .- 1873-4235. ; 24:5, s. 1365-1371
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Journal article (peer-reviewed)abstract
- Immobilisation of biorecognition elements on transducer surfaces is a key step in the development of biosensors. The immobilisation needs to be fast, cheap and most importantly should not affect the biorecognition activity of the immobilised receptor. A novel protocol for the covalent immobilisation of biomolecules containing primary amines using an inexpensive and simple polymer is presented. This tridimensional (3D) network leads to a random immobilisation of antibodies on the polymer and ensures the availability of a high percentage of antibody binding sites. The reactivity of the polymer is based on the reaction between primary amines and thioacetal groups included in the polymer network. These functional groups (thioacetal) do not need any further activation in order to react with proteins, making it attractive for sensor fabrication. The novel polymer also contains thiol derivative groups (disulphide groups or thioethers) that promote self-assembling on a metal transducer surface. For demonstration purposes the polymer was immobilised on Au Biacore chips. The resulting polymer layer was characterised using contact angle meter, atomic force microscopy (AFM) and ellipsometry. A general protocol suitable for the immobilisation of bovine serum albumin (BSA), enzymes and antibodies such as polyclonal anti-microcystin-LR antibody and monoclonal anti-prostate specific antigen (anti-PSA) antibody was then optimised. The affinity characteristics of developed immunosensors were investigated in reaction with microcystin-LR, and PSA. The calculated detection limit for analytes depended on the properties of antibodies. The detection limit for microcystin-LR was 10 ng mL(-1) and for PSA 0.01 ng mL(-1). The non-specific binding of analytes to synthesised polymers was very low. The polymer-coated chips were stored for up to 2 months without any noticeable deterioration in their ability to react with proteins. These findings make this new polymer very promising for the development of low-cost, easy to prepare and sensitive biosensors. (C) 2008 Elsevier B.V. All rights reserved.
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| 4. |
- Kyprianou, Dimitris, et al.
(author)
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The application of polythiol molecules for protein immobilisation on sensor surfaces
- 2010
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In: Biosensors & bioelectronics. - : Elsevier Science B.V., Amsterdam.. - 0956-5663 .- 1873-4235. ; 25:5, s. 1049-1055
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Journal article (peer-reviewed)abstract
- The immobilisation of bio-receptors on transducer surfaces is a key step in the development of biosensors. The immobilisation needs to be fast, cheap and most importantly should not affect the biorecognition activity of the immobilised receptor. The development of a protocol for biomolecule immobilisation onto a surface plasmon resonance (SPR) sensor surface using inexpensive polythiol compounds is presented here. The method used here is based on the reaction between primary amines and thioacetal groups, formed upon reaction of o-phthaldialdehyde (OPA) and thiol compounds. The self-assembled thiol monolayers were characterised using contact angle and XPS. The possibility to immobilise proteins on monolayers was assessed by employing BSA as a model protein. For the polythiol layers exhibiting the best performance, a general protocol was optimised suitable for the immobilisation of enzymes and antibodies such as anti-prostate specific antigen (anti-PSA) and anti Salmonella typhimurium. The kinetic data was obtained for PSA binding to anti-PSA and for S. typhimurium cells with a detection limit of 5 x 10(6) cells mL(-1) with minimal non-specific binding of other biomolecules. These findings make this technique a very promising alternative for amine coupling compared to peptide bond formation. Additionally, it offers opportunity for immobilising proteins (even those with low isoelectric point) on neutral polythiol layers without any activation step. (C) 2009 Elsevier B.V. All rights reserved.
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| 5. |
- Mijangos, Irene, et al.
(author)
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Influence of initiator and different polymerisation conditions on performance of molecularly imprinted polymers
- 2006
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In: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 22:3, s. 381-387
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Journal article (peer-reviewed)abstract
- A set of polymers was imprinted with (-)-ephedrine using two different initiators. A chemometrics approach was used to optimise experiments aimed at analysis of the interplay of parameters such as polymerisation time, temperature and percentage of initiator. The results presented demonstrate the importance of keeping the right balance between these various parameters of polymerisation conditions. It is shown that enhancing one single parameter such as polymer rigidity does not necessarily improve polymer performance. In general it could be concluded that MIPs should be synthesised over a long period of time using low concentration of initiator and low temperature. The best selectivity was achieved for polymers prepared by photo-initiation with 2,2-dimethoxy-2-phenylacetophenone as initiator.
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| 6. |
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| 7. |
- Piletska, Elena, et al.
(author)
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Optical biosensors based on universal pH indicator as a reporter for quantification of clinically-relevant compounds
- 2014
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In: Journal of the Chinese Advanced Materials Society. - : Taylor & Francis. - 2168-1031 .- 2224-3682. ; 2:2, s. 99-109
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Journal article (peer-reviewed)abstract
- It was shown that universal indicator, a blend of pH-sensitive dyes which changes colour from red to purple over broad pH value range, in combination with a disposable optical sensor chip, could be used for the monitoring of physiologically important compounds. Changes in the optical properties of pH-sensitive dyes in the presence of enzyme catalysed reactions allowed quick and sensitive evaluation of the concentration of clinically important analytes such as glucose and urea. It was shown that the proposed optical biosensor could provide a sensitive and inexpensive method for the quantification of urea in plasma over a concentration range of 5–50 mM and glucose in the concentration range 1–25 mM. The system provides a generic platform that can be combined with other appropriate enzymes for the quantification of a range of physiological compounds to furnish versatile and portable clinical multisensors.
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| 8. |
- Piletska, Elena V., et al.
(author)
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Towards the development of multisensor for drugs of abuse based on molecular imprinted polymers
- 2005
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In: Analytica Chimica Acta. - : ELSEVIER SCIENCE BV. - 0003-2670 .- 1873-4324. ; 542:1, s. 111-117
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Journal article (peer-reviewed)abstract
- The synthetic receptors for cocaine, deoxyephedrine, methadone and morphine were computationally designed and produced using molecular imprinting. The structure and energy of the molecular complexes were analysed by computational techniques. The possible structures of the binding sites in the synthetic receptors have been compared with those of corresponding natural receptors. The composition of imprinted polymers was optimised to allow adequate performance under the same experimental conditions. All selected molecular imprinting polymers (MIPs) demonstrated stronger affinity in comparison with corresponding blank polymers resulting in imprinted factors (1) equal to 1.2 (cocaine), 2.5 (deoxyephedrine), 3.5 (methadone) and 3 (morphine) which suggested that the specific binding site for each molecule was successfully created. The polymers studied possessed good selectivity and affinity towards their templates and could be recommended for the integration with sensor devices. From a practical point of view, especially for multisensor requirements, the synthetic receptors based on imprinted polymers could be superior to natural receptors due to their stability, robustness and compatibility with automation processes required for sensor fabrication.
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| 9. |
- Romero Guerra, Maria, et al.
(author)
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Development of a piezoelectric sensor for the detection of methamphetamine
- 2009
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In: The Analyst. - : Royal Society of Chemistry. - 0003-2654 .- 1364-5528. ; 134:8, s. 1565-1570
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Journal article (peer-reviewed)abstract
- A computationally designed molecularly imprinted polymer (MIP) specific for methamphetamine was used as a synthetic receptor for the development of a piezoelectric sensor. Several different protocols were tested for the immobilisation of the MIP onto the gold sensor surface. The developed MIP sensor had a detection limit for methamphetamine as low as 1 mu g mL(-1). The effect of the addition of poly(vinyl acetate) (PVA) on the pre-polymerisation mixtures, which increases the porosity of the polymer layer, was also studied using an Atomic Force Microscope (AFM). PVA seemed to affect both the porosity and the binding kinetics of the polymers prepared in dimethylformamide (DMF). However, no clear effect on porosity and binding kinetics was observed when polymers were prepared in diglyme. Moreover, PVA did not appear to improve the amplitude of the sensor response. In conclusion, because of its excellent recognition ability in aqueous solutions, the sensor described in this work could be an ideal starting point for the development of a commercial device for fast, on-site or road-side testing of drugs of abuse in body fluids such as saliva.
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| 10. |
- V. Piletska, Elena, et al.
(author)
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Design of molecular imprinted polymers compatible with aqueous environment
- 2008
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In: Analytica Chimica Acta. - : Elsevier Science B.V., Amsterdam.. - 0003-2670 .- 1873-4324. ; 607:1, s. 54-60
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Journal article (peer-reviewed)abstract
- The main problem of poor water compatibility of molecularly imprinted polymers (MIPs) was addressed in examples describing design of synthetic receptors with high affinity for drugs of abuse. An extensive potentiometric titration of 10 popular functional monomers and corresponding imprinted and Blank polymers was conducted in order to evaluate the subtleties of functional groups ionisation under aqueous conditions. It was found that polymers prepared using 2-trifluoromethacrylic acid (TFMAA) in combination with toluene as porogen possess superior properties which make them suitable for effective template recognition in water. The potential impact of phase separation during polymerisation on formation of high quality imprints has been discussed. Three drugs of abuse such as cocaine, deoxyephedrine and methadone were used as template models in polymer preparation for the practical validation of obtained results. The polymer testing showed that synthesized molecularly imprinted polymers have high affinity and selectivity for corresponding templates in aqueous environment, with imprinting factors of 2.6 for cocaine and 1.4 for methadone and deoxyephedrine. Corresponding Blank polymers were unable to differentiate between analytes, suggesting that imprinting phenomenon was responsible for the recognition properties. (c) 2007 Elsevier B.V. All rights reserved.
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