Browsing by Author "Mijangos, Irene"

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Influence of continuous magnetic field on the performance of molecularly imprinted polymers
    (Elsevier Science B.V., Amsterdam., 2008-02-28T00:00:00Z) Guerreiro, Antonio R.; Korkhov, Vadim; Mijangos, Irene; Piletska, Elena V.; Rodins, Juris; Turner, Anthony P. F.; Piletsky, Sergey A.
    A set of polymers was imprinted with (−)-ephedrine using UV initiation, under the influence of a constant external magnetic field with intensities ranging from 0 to 1.55 T. Synthesised materials were characterised by X-ray crystallography, infrared spectroscopy, swelling and surface area. Recognition properties were assessed by the ability to discriminate between (+) and (−)- ephedrine and by Scatchard analyses on chromatographic mode. It was shown that polymer morphology and recognition properties are affected by the magnetic field. This resulted in considerable improvements in the chromatographic resolution of ephedrine enantiomers by materials synthesised under the influence of magnetic field. Apparently the magnetic field improved the ordering of the polymer structure and facilitated the formation of more uniform imprinting s
  • Thumbnail Image
    ItemOpen Access
    Influence of initiator and different polymerisation conditions on performance of molecularly imprinted polymers
    (Elsevier Science B.V., Amsterdam., 2006-09-15T00:00:00Z) Mijangos, Irene; Navarro-Villoslada, Fernando; Guerreiro, Antonio R.; Piletska, Elena V.; Chianella, Iva; Karim, Kal; Turner, Anthony P. F.; Piletsky, Sergey A.
    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 initiatotor
  • Thumbnail Image
    ItemOpen Access
    The stabilisation of receptor structure in low cross-linked MIPs by an immobilised template
    (Royal Society of Chemistry, 2009-01-21T00:00:00Z) Garcinuno, Rosa M.; Chianella, Iva; Guerreiro, Antonio R.; Mijangos, Irene; Piletska, Elena V.; Whitcombe, Michael J.; Piletsky, Sergey A.
    In molecularly imprinted polymers (MIPs) a high level of cross-linking is usually important for preserving the receptor structure. We propose here an alternative approach for stabilising binding sites, which involves the use of an immobilised template. The idea is based on the assumption that an immobilised template will ‘‘hold’’ polymeric chains and complementary functionalities together, preventing the collapsing of the binding sites. To test this postulate, a range of polymers was prepared using polymerisable (2,4-diamino-6- (methacryloyloxy)ethyl-1,3,5-triazine) and non-polymerisable (or extractable) (2,4-diamino-6-methyl-1,3,5-triazine) templates, methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linker. The level of cross-linking was varied from 12 to 80%. Polymerisations were performed in acetonitrile using UV initiation. Binding properties of the synthesised materials were characterised both by HPLC and equilibrium batch binding experiments followed by HPLC-MS or UV-visible detection. The adsorption isotherms of polymers were obtained and fitted to the Langmuir model to calculate dissociation constant, Kd, and concentration of binding sites for each material. The results strongly indicate that the presence of an immobilised template improves the affinity of MIPs containing low percentages of cross-linker. The low cross-linked MIPs synthesised with a polymerisable template also retain a reasonable degree of selectivity. Low crosslinked MIPs with such binding characteristics would be useful for the creation of new types of optical and electrochemical sensors, where induced fit or the ‘‘gate effect’’ could be used more effectively for generating and enhancing sensor signals.