Browsing by Author "Turner, Nicholas W."
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Item Embargo Analytical methods for determination of mycotoxins: An update (2009–2014)(Elsevier, 2015-10-26) Turner, Nicholas W.; Brahmbhatt, Heli; Szabo-Vezse, Monika; Poma, Alessandro; Coker, Raymond; Piletsky, Sergey A.Mycotoxins are a problematic and toxic group of small organic molecules that are produced as secondary metabolites by several fungal species that colonise crops. They lead to contamination at both the field and postharvest stages of food production with a considerable range of foodstuffs affected, from coffee and cereals, to dried fruit and spices. With wide ranging structural diversity of mycotoxins, severe toxic effects caused by these molecules and their high chemical stability the requirement for robust and effective detection methods is clear. This paper builds on our previous review and summarises the most recent advances in this field, in the years 2009–2014 inclusive. This review summarises traditional methods such as chromatographic and immunochemical techniques, as well as newer approaches such as biosensors, and optical techniques which are becoming more prevalent. A section on sampling and sample treatment has been prepared to highlight the importance of this step in the analytical methods. We close with a look at emerging technologies that will bring effective and rapid analysis out of the laboratory and into the field.Item Open Access Application of Molecularly Imprinted Polymers in the Anti-Doping Field: Sample Purification and Compound Analysis(Royal Society of Chemistry, 2020-06-01) Hand, Rachel; Piletska, Elena; Bassindale, Thomas; Morgan, Geraint; Turner, Nicholas W.The problem posed by anti-doping requirements is one of the great analytical challenges; multiple compound detection at low ng ml−1 levels from complex samples, with requirements for exceptional confidence in results. This review surveys the design, synthesis and application of molecularly imprinted polymers (MIPs) in this field, focusing on the templating of androgenous anabolic steroids (AASs), as the most commonly abused substances, but also other WADA prohibited substances. Commentary on the application of these materials in detection, clean-up and sensing is offered, alongside views on the future of imprinting in this field.Item Embargo Detection of multiple steroidal compounds in synthetic urine using comprehensive gas chromatography-mass spectrometry (GC×GC-MS) combined with a molecularly imprinted polymer clean-up protocol(Royal Society of Chemistry, 2014-07-17) Zulfiqar, Adnan; Morgan, Geraint; Turner, Nicholas W.method capable of screening for multiple steroids in urine has been developed, using a series of twelve structurally similar, and commercially relevant compounds as target analytes. A molecularly imprinted solid phase extraction clean-up step was used to make the sample suitable for injection onto a GC×GC-MS setup. Significant improvements compared to a commercially available C-18 material were observed. Each individual steroid was able to be separated and identified, using both the retention profile and diagnostic fragmentation ion monitoring abilities of the comprehensive chromatographic-mass spectrometry method. Effective LODs of between 11.7 and 27.0 pg were calculated for individual steroids, effectively equivalent to concentration levels of between 0.234 and 0.540 ng mL−1 in urine, while the application of multiple screen was demonstrated using a 10 ng mL−1 mixed sample. The nature of this study also removes the need for sample derivitisation which speeds up the screening process.Item Open Access Development of sample clean up methods for the analysis of Mycobacterium tuberculosis methyl mycocerosate biomarkers in sputum extracts by gas chromatography–mass spectrometry(Elsevier, 2015-02-16) Turner, Nicholas W.; Minnikin, David E.; Lee, Oona Y.-C; O'Sullivan, Denise M.; McNerney, Ruth; Mutetwa, Reggie; Corbett, Liz E.; Morgan, Geraint; Nicoara, Simona C.proof of principle gas chromatography–mass spectrometry method is presented, in combination with clean up assays, aiming to improve the analysis of methyl mycocerosate tuberculosis biomarkers from sputum. Methyl mycocerosates are generated from the transesterification of phthiocerol dimycocerosates (PDIMs), extracted in petroleum ether from sputum of tuberculosis suspect patients. When a high matrix background is present in the sputum extracts, the identification of the chromatographic peaks corresponding to the methyl derivatives of PDIMs analytes may be hindered by the closely eluting methyl ether of cholesterol, usually an abundant matrix constituent frequently present in sputum samples. The purification procedures involving solid phase extraction (SPE) based methods with both commercial Isolute-Florisil cartridges, and purpose designed molecularly imprinted polymeric materials (MIPs), resulted in cleaner chromatograms, while the mycocerosates are still present. The clean-up performed on solutions of PDIMs and cholesterol standards in petroleum ether show that, depending on the solvent mix and on the type of SPE used, the recovery of PDIMs is between 64 and 70%, whilst most of the cholesterol is removed from the system. When applied to petroleum ether extracts from representative sputum samples, the clean-up procedures resulted in recoveries of 36–68% for PDIMs, allowing some superior detection of the target analytes.Item Open Access Effect of polymerisation by microwave on the physical properties of molecularly imprinted polymers (MIPs) specific for caffeine(Royal Society of Chemistry, 2020-08-12) Brahmbhatt, Heli A.; Surtees, Alexander; Tierney, Cavan; Ige, Oluwabukunmi A.; Piletska, Elena V.; Swift, Thomas; Turner, Nicholas W.Molecularly Imprinted Polymers (MIPs) are a class of polymeric materials that exhibit highly specific recognition properties towards a chosen target. These "smart materials" offer robustness to work in extreme environmental conditions and cost effectiveness; and have shown themselves capable of the affinities/specificities observed of their biomolecular counterparts. Despite this, in many MIP systems heterogeneity generated in the polymerisation process is known to affect the performance. Microwave reactors have been extensively studied in organic chemistry because they can afford fast and well-controlled reactions, and have been used for polymerisation reactions; however, their use for creating MIPs is limited. Here we report a case study of a model MIP system imprinted for caffeine, using microwave initiation. Experimental parameters such as polymerisation time, temperature and applied microwave power have been investigated and compared with polymers prepared by oven and UV irradiation. MIPs have been characterised by BET, SEM, DSC, TGA, NMR, and HPLC for their physical properties and analyte recognition performance. The results suggest that the performance of these polymers correlates to their physical characteristics These characteristics were significantly influenced by changes in the experimental polymerisation parameters, and the complexity of the component mixture. A series of trends were observed as each parameter was altered, suggesting that the performance of a generated polymer could be possible to predict. As expected, component selection is shown to be a major factor in the success of an imprint using this method, but this also have significant effect on the quality of resultant polymers suggesting that only certain types of MIPs can be made using microwave irradiation. This work also indicates that the controlled polymerisation conditions offered by microwave reactors could open a promising future in the development of MIPs with more predictable analyte recognition performance, assuming material selection loans itself to this type of initiation.Item Embargo Generation of High-Affinity Molecularly Imprinted Nanoparticles for Protein Recognition via a Solid-Phase Synthesis Protocol(Humana, 2019-10-15) Canfarotta, Francesco; Piletsky, Sergey; Turner, Nicholas W.Molecularly imprinted polymers are leading technology in the development of protein biomimetics. This chapter describes the protocol for the synthesis of protein imprinted nanoparticles. These materials exhibit exceptional affinity (into the nM/pM range) and selectivity for their target template. The nanoparticles can be developed for a wide range of targets, while exhibiting excellent robustness, solubility, and flexibility in use. They are finding use in the creation of drug delivery vectors and sensing and recognition assays.Item Open Access Generation of novel hybrid aptamer-molecularly imprinted polymeric nanoparticles(Wiley, 2015-01-21) Poma, Alessandro; Brahmbhatt, Heli; Pendergraff, H. M; Watts, Jonathan K; Turner, Nicholas W.A strategy to exploit aptamers as recognition elements of molecularly imprinted polymeric nanoparticles (AptaMIP NPs) is presented, via modification of the chemical structure of the DNA. It is demonstrated that the introduction of this modified “aptamer monomer” results in an increase of the affinity of the produced MIP NPs, without altering their physical properties such as size, shape, or dispersibility.Item Open Access Hybrid Aptamer-Molecularly Imprinted Polymer (aptaMIP) Nanoparticles from Protein Recognition—A Trypsin Model(Wiley, 2021-03-24) Sullivan, Mark; Clay, Oliver; Moazami, Michael; Watts, Jonathan; Turner, Nicholas W.Aptamers offer excellent potential for replacing antibodies for molecular recognition purposes however their performance can compromise with biological/environmental degradation being a particular problem. Molecularly imprinted polymers (MIPs) offer an alternative to biological materials and while these offer the robustness and ability to work in extreme environmental conditions, they often lack the same recognition performance. By slightly adapting the chemical structure of a DNA aptamer we have incorporated it for use as the recognition part of a MIP, thus creating an aptamer-MIP hybrid or aptaMIP. Here we have developed these for the detection of the target protein trypsin. The aptaMIP nanoparticles offer superior binding affinity over conventional MIP nanoparticles (nanoMIPs), with KD values of 6.8 × 10-9 (± 0.2 × 10-9) M and 12.3 × 10-9 (± 0.4 × 10-9) M for the aptaMIP and nanoMIP, respectively. The aptaMIP also outperforms the aptamer only (10.3 x 10-9 M). Good selectivity against other protein targets is observed. Using Surface Plasmon Resonance, the limit of detection for aptaMIP nanoparticles was two-fold lower (2nM) compared to the nanoMIP (4 nM). Introduction of the aptamer as a “macro-monomer” into the MIP scaffold has beneficial effects and offers potential to improve this class of polymers significantly.Item Open Access Improvement of DNA recognition through molecular imprinting: hybrid oligomer imprinted polymeric nanoparticles (oligoMIP NPs)(Royal Society of Chemistry, 2015-08-26) Brahmbhatt, H.; Poma, A.; Pendergraff, H. M.; Watts, J. K.; Turner, Nicholas W.High affinity and specific binding are cardinal properties of nucleic acids in relation to their biological function and their role in biotechnology. To this end, structural preorganization of oligonucleotides can significantly improve their binding performance, and numerous examples of this can be found in Nature as well as in artificial systems. Here we describe the production and characterization of hybrid DNA–polymer nanoparticles (oligoMIP NPs) as a system in which we have preorganized the oligonucleotide binding by molecular imprinting technology. Molecularly imprinted polymers (MIPs) are cost-effective “smart” polymeric materials capable of antibody-like detection, but characterized by superior robustness and the ability to work in extreme environmental conditions. Especially in the nanoparticle format, MIPs are dubbed as one of the most suitable alternatives to biological antibodies due to their selective molecular recognition properties, improved binding kinetics as well as size and dispersibility. Nonetheless, there have been very few attempts at DNA imprinting in the past due to structural complexity associated with these templates. By introducing modified thymine bases into the oligonucleotide sequences, which allow establishing covalent bonds between the DNA and the polymer, we demonstrate that such hybrid oligoMIP NPs specifically recognize their target DNA, and that the unique strategy of incorporating the complementary DNA strands as “preorganized selective monomers” improves the recognition properties without affecting the NPs physical properties such as size, shape or dispersibility.Item Open Access Influence of surface-imprinted nanoparticles on trypsin activity(Wiley, 2014-03-20) Poma, Alessandro; Karim, Kal; Moczko, Ewa; Takarada, Jessica; de Vargas-Sansalvador, Isabel; Piletska, Elena; Glazova, Natalia; Serkova, Anastasia; Omelianova, Aleksandra; Piletsky, Sergey; Turner, Nicholas W.; Guerreiro, Antonio; de Magalhaes, Cristiana SchmidtHere, the modulation of enzyme activity is presented by protein‐imprinted nanoparticles produced using a solid‐phase approach. Using trypsin as target, binding of the nanoparticles to the enzyme results in its inhibition or in stabilization, depending on the orientation of the immobilized enzyme used during imprinting.Item Open Access Nucleoside-tailored molecularly imprinted polymeric nanoparticles (MIP NPs)(ACS, 2014-09-12) Poma, Alessandro; Brahmbhatt, Heli; Watts, Jonathan K; Turner, Nicholas W.MIP NPs represent one of the current most suitable alternatives to antibodies for molecular recognition and diagnostic applications. Here we present the synthesis of MIP NPs imprinted for 2′-deoxyadenosine (dA) prepared using for the first time a modified polymerizable 2′-deoxyuridine complementary residue. We demonstrate that the introduction of this modified monomer results in an increase of the affinity of the produced MIP NPs, without altering their physical properties such as size, shape, or dispersibility. The imprinted NPs have shown the ability to specifically recognize dA, whereas no imprinting effect was observed for 2′-deoxyguanosine (dG) or deoxycytidine (dC). The results suggest that such monomers (and their phosphoramidites) could be used in the synthesis of oligomer or longer DNA sequences for potentially producing hybrid MIP–DNA materials with improved recognition performance.Item Embargo Polythiophene nanofilms for sensitive fluorescence detection of viruses in drinking water(Elsevier, 2016-03-11) Wankar, Shashwati; Turner, Nicholas W.; Krupadam, Reddithota J.Molecular imprints of the tobacco necrosis virus (TNV) have been formed within polythiophene nanofilms with an approximate thickness of 200 nm. These films have been electrochemically deposited onto conducting Au surfaces. Upon rebinding, the TNV-polythiophene complex changes the fluorescence intensity of the nanofilm. The fluorescence intensity at 410 nm was observed to be proportional to the concentration of viruses in the range of 0.1–10 ng L−1 (0.15–15 pg) with the lower calculated detection limit of 2.29 ng L−1 (3.4 pg). The intensity of the fluorescence emission is not affected by the thickness of the polythiophene film and the nature of TNV specific binding sites. Kinetic data analyses showed that the nanofilm responds to TNV within 2 min; and cross-selectivity studies with tobacco mosaic virus (TMV) showed an excellent specificity for the targeted TNV. These binding experiments demonstrate the potential of fluorescence emission for the specific, label free and rapid detection of viruses using nanofilm sensors. Taking into account the lower limit of detection, the fluorescence sensing reported here is reliable, simple to perform, rapid, cost-effective and offers a sensitive analytical method for virus detection in water resources.Item Open Access Spotlight on medicinal chemistry education(Taylor and Francis, 2014-06-25) Pitman, Simone; Xu, Yao; Taylor, Peter; Turner, Nicholas W.The field of medicinal chemistry is constantly evolving and it is important for medicinal chemists to develop the skills and knowledge required to succeed and contribute to the advancement of the field. Future Medicinal Chemistry spoke with Simone Pitman (SP), Yao-Zhong Xu (YX), Peter Taylor (PT) and Nick Turner (NT) from The Open University (OU), which offers an MSc in Medicinal Chemistry. In the interview, they discuss the MSc course content, online teaching, the future of medicinal chemistry education and The OU’s work towards promoting widening participation. SP is a Qualifications Manager in the Science Faculty at The OU. She joined The OU in 1993 and since 1998 has been involved in the Postgraduate Medicinal Chemistry provision at The OU. YX is a Senior Lecturer in Bioorganic Chemistry at The OU. He has been with The OU from 2001, teaching undergraduate courses of all years and chairing the master’s course on medicinal chemistry. PT is a Professor of Organic Chemistry at The OU and has been involved with the production and presentation of The OU courses in Science and across the university for over 30 years, including medicinal chemistry modules at postgraduate level. NT is a Lecturer in Analytical Science at The OU since 2009 and has been involved in the production of analytical sciences courses, as well as contributing to the presentation of a number of science courses including medicinal chemistry.Item Embargo Trifluorosilane induced structural transitions in beta-lactoglobulin in sol and gel(Elsevier, 2014-04-30) Peng, Yun; Turner, Nicholas W.; Britt, David W.Fluoroalcohols such as 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) are strong inducers of protein secondary structure. Here, hydrolyzed (3,3,3-trifluoropropyl)trimethoxysilane (3F) is demonstrated to exhibit greater protein conformation inducing activity than HFIP, which is preserved when 3F is copolymerized in tetraethylorthosilicate (TEOS) sol–gels through protein molecular imprinting. Hydrolyzed 3F formed a pre-polymerization complex with the template protein, β-lactoglobulin, inducing distinct α-helical structures as evidenced by circular dichroism. Fluorescence resonance energy transfer between tryptophan and the lipophilic probe 1-anilinonaphthalene-8-sulfonic acid showed a sharp molten globule (MG) transition at 0.2 M 3F, whereas HFIP induced a broad MG transition centered at 0.6 M HFIP. The 3F-induced BLG conformation transitions were retained upon gelation, validating use of the fluorosilane as a conformation directing functional monomer readily incorporated into sol–gels.Item Open Access The use of Quartz Crystal Microbalance as an analytical tool to monitor particles/surface and particle/particle interactions in dry ambient and pressurized conditions: a study using common inhaler components(Royal Society of Chemistry, 2016-11-24) Bloxham, M.; Chianella, I.; Turner, Nicholas W.; Piletsky, S. A.; Whitcombe, M. J.Metered dose inhalers (MDI) and multidose powder inhalers (MPDI) are commonly used for the treatment of chronic obstructive pulmonary diseases and asthma. Currently, analytical tools to monitor particle/particle and particle/surface interaction within MDI and MPDI at the macro-scale do not exist. A simple tool capable of measuring such interactions would ultimately enable quality control of MDI and MDPI, producing remarkable benefits for the pharmaceutical industry and the users of inhalers. In this paper, we have investigated whether quartz crystal microbalance (QCM) could become such a tool. QCM was used to measure particle/particle and particle/surface interactions on the macro scale, by additions of small amount of MDPI components, in powder form into a gas stream. The subsequent interactions with material on the surface of the QCM sensor were analyzed. Following this, the sensor was used to measure fluticasone propionate, a typical MDI active ingredient, in a pressurized gas system to assess its interactions with different surfaces under conditions mimicking the manufacturing process. In both types of experiment QCM was capable to discriminate interactions of different components and surfaces. The results have demonstrated that QCM is a suitable platform for monitoring macroscale interactions and could possibly become a tool for quality control of inhalers.