Browsing by Author "Turner, Nicholas W."
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Item Open Access Controlled release of the herbicide simazine from computationally designed molecularly imprinted polymers(Elsevier Science B.V., Amsterdam., 2005-11-02T00:00:00Z) Piletska, Elena V.; Turner, Nicholas W.; Turner, Anthony P. F.; Piletsky, Sergey A.The present study describes the development of materials suitable for environmental control of algae. Molecularly imprinted polymers (MIPs) were used as simazine carriers able to provide the controlled release of simazine into water. Three polymers were designed using computational modelling. The selection of methacrylic acid (MA) and hydroxyethyl methacrylate (HEM) as functional monomers was based on results obtained using the Leapfrog™ algorithm. A cross- linked polymer made without functional monomers was also prepared and tested as a control. The release of simazine from all three polymers was studied. It was shown that the presence of functional monomers is important for polymer affinity and for controlled release of herbicide. The speed of release of herbicide correlated with the calculated binding characteristics. The high-affinity MA- based polymer released 2% and the low-affinity HEM-based polymer released 27% of the template over 25 days. The kinetics of simazine release from HEM-based polymer show that total saturation of an aqueous environment could be achieved over a period of 3 weeks and this corresponds to the maximal simazine solubility in water. The possible use of these types of polymers in the field of controlled release is discusseItem Open Access Deposition of functionalized polymer layers in surface plasmon resonance immunosensors by in-situ polymerization in the evanescent wave field(Elsevier Science B.V., Amsterdam., 2009-01-01T00:00:00Z) Chegel, Vladimir; Whitcombe, Michael J.; Turner, Nicholas W.; Piletsky, Sergey A.Traditionally, the integration of sensing gel layers in surface plasmon resonance (SPR) is achieved via “bulk” methods, such as precipitation, spin- coating or in-situ polymerization onto the total surface of the sensor chip, combined with covalent attachment of the antibody or receptor to the gel surface. This is wasteful in terms of materials as the sensing only occurs at the point of resonance interrogated by the laser. By isolating the sensing materials (antibodies, enzymes, aptamers, polymers, MIPs, etc.) to this exact spot a more efficient use of these recognition elements will be achieved. Here we present a method for the in-situ formation of polymers, using the energy of the evanescent wave field on the surface of an SPR device, specifically localized at the point of interrogation. Using the photo-initiator couple of methylene blue (sensitizing dye) and sodium p-toluenesulfinate (reducing agent) we polymerized a mixture of N,N-methylene-bis-acrylamide and methacrylic acid in water at the focal point of SPR. No polymerization was seen in solution or at any other sites on the sensor surface. Varying parameters such as monomer concentration and exposure time allowed precise control over the polymer thickness (from 20–200 nm). Standard coupling with 1-ethyl-3-(3- dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide was used for the immobilization of protein G which was used to bind IgG in a typical biosensor format. This model system demonstrated the characteristic performance for this type of immunosensor, validating our deposition mItem Open Access A development of a molecularly imprinted polymer: Specific for ochratoxin A: Theoretical and sensor applications(Cranfield University, 2004-01) Turner, Nicholas W.; Piletsky, Sergey A.; Magan, NareshIn this work the development of two molecularly imprinted polymers, specific for ochratoxin A, is presented. Ochratoxin A is produced by several Aspergillus and Penicillium species and is common in cereals and other starch rich foods and has also been found in coffee, dried fruits, wine, beer and meats. It demonstrates potent teratogenic, immunosuppressive, mutagenic and carcinogenic properties. The toxin is also linked to Balkan Endemic Nephropathy, a chronic kidney disease found in South-Eastern Europe. Due to this the European Union has set limits on foodstuffs ranging between 2-10 ng g-1. Therefore the requirement of a simple and inexpensive biosensor to monitor this legislation is a necessity. Currently detection is performed by chromatographic methods such as HPLC, and by ELISA formats. In this work two polymeric materials, rationally designed by computational modelling and synthesised using molecular imprinting, are studied. The modelling is complimented with a Nuclear Magnetic Resonance (NMR) study. The first polymer (Polymer A) consisted of 1 mol of acrylamide and 1 mol of methacrylic acid to 1 mol of template. This material demonstrated an unusual binding mechanism, working solely in aqueous solvents. A theoretical mechanism for this binding is presented and discussed. The second polymer, again rationally designed, but under different conditions, consisted of 1 mol of N,N- diethylamino ethyl methacrylate (DEAEM) to 1 mol of template. This polymer demonstrated high affinity for the template in acetonitrile. Polymer A is used in combination with an ion-exchange SPE protocol (developed for this purpose) for the extraction of OTA from maize. Both polymer compositions are used in development of a MIP membrane optical sensor, with partial success seen in the detection of OTA in grape juice and white wine.Item Open Access The use of a quartz crystal microbalance as an analytical tool to monitor particle/surface and particle/particle interactions under dry ambient and pressurized conditions: a study using common inhaler components(Royal Society of Chemistry, 2016-11-24) Turner, Nicholas W.; Bloxham, M.; Piletsky, Sergey A.; Whitcombe, Michael J.; Chianella, IvaMetered 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 a quartz crystal microbalance (QCM) could become such a tool. A QCM was used to measure particle/particle and particle/surface interactions on the macroscale, by additions of small amounts of MDPI components, in the powder form into a gas stream. The subsequent interactions with materials 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 experiments the QCM was capable of discriminating interactions of different components and surfaces. The results have demonstrated that the QCM is a suitable platform for monitoring macro-scale interactions and could possibly become a tool for quality control of inhalers.