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  • 1.
    Olsson, Gustaf D.
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karlsson, Björn C. G.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Shoravi, Siamak
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Wiklander, Jesper G.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Mechanisms Underlying Molecularly Imprinted Polymer Molecular Memory and The Role of Crosslinker: Resolving Debate on the Nature of Template Recognition in Phenylalanine Anilide Imprinted Polymers2012In: Journal of Molecular Recognition, ISSN 0952-3499, E-ISSN 1099-1352, Vol. 25, no 2, p. 69-73Article in journal (Refereed)
    Abstract [en]

    A series of molecular dynamics simulations of prepolymerization mixtures for phenylalanine anilide imprinted co-(ethylene glycol dimethacrylate-methacrylic acid) molecularly imprinted polymers have been employed to investigate the mechanistic basis for template selective recognition in these systems. This has provided new insights on the mechanisms underlying template recognition, in particular the significant role played by the crosslinking agent. Importantly, the study supports the occurrence of template self-association events that allows us to resolve debate between the two previously proposed models used to explain this system's underlying recognition mechanisms. Moreover, the complexity of the molecular level events underlying template complexation is highlighted by this study, a factor that should be considered in rational molecularly imprinted polymer design, especially with respect to recognition site heterogeneity.

  • 2.
    Rosengren, Annika M.
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karlsson, Björn C. G.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Monitoring of the distribution of warfarin in blood plasma2012In: ACS Medicinal Chemistry Letters, ISSN 1948-5875, E-ISSN 1948-5875, Vol. 3, no 8, p. 650-652Article in journal (Refereed)
    Abstract [en]

    Warfarin is an anticoagulant drug extensively used in the treatment and prevention of thrombotic disorders. Previous studies have shown that warfarin binds extensively to blood plasma proteins and that only a small fraction of the drug is unbound and thus available for therapeutic function. Both warfarin's narrow therapeutic window and the susceptibility of anticoagulant function to patient-dependent factors necessitate regular monitoring. In this study, we have shown that the lifetimes for each of the various bound and free forms of the drug in blood plasma can be quantified in situ by time-correlated single-photon counting fluorescence spectroscopy over the clinically significant concentration range. A relationship between the blood coagulation and the distribution of fluorescence lifetimes was observed. The in situ detection of clinically relevant concentrations of warfarin in its respective bound and unbound forms could provide a prognostic tool for use in patient treatment.

  • 3.
    Rosengren, Annika M.
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karlsson, Björn C. G.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Näslund, Inga
    Andersson, Per Ola
    Nicholls, Ian A.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    In situ detection of warfarin using time-correlated single-photon counting.2011In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 407, no 1, p. 60-62Article in journal (Refereed)
    Abstract [en]

    Here we report on a novel method for the direct in situ measurement of specific isomeric forms of the anticoagulant warfarin using time correlated single-photon counting (TCSPC) spectroscopy in conjunction with synthetic Sudlow I binding site receptors. The method is highly robust over the clinically significant concentration range, and demonstrates the potential of the binding site mimics in conjunction with the spectroscopic strategy employed here for the determination of this important pharmaceutical in clinical or even environmental samples.

  • 4.
    Nicholls, Ian A.
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Andersson, Håkan S.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Golker, Kerstin
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Henschel, Henning
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karlsson, Björn C. G.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Olsson, Gustaf D.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rosengren, Annika M.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Shoravi, Siamak
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Wiklander, Jesper G.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Wikman, Susanne
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rational Design of Biomimetic Molecularly Imprinted Materials: Theoretical and Computational Strategies for Guiding Nanoscale Structured Polymer Development2011In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 400, p. 1771-1786Article, review/survey (Refereed)
    Abstract [en]

    In principle, molecularly imprinted polymer science and technology provides a means for ready access to nano-structured polymeric materials of predetermined selectivity. The versatility of the technique has brought it to the attention of many working with the development of nanomaterials with biological or biomimetic properties for use as therapeutics or in medical devices. Nonetheless, the further evolution of the field necessitates the development of robust predictive tools capable of handling the complexity of molecular imprinting systems. The rapid growth in computer power and software over the past decade has opened new possibilities for simulating aspects of the complex molecular imprinting process. We present here a survey of the current status of the use of in silico-based approaches to aspects of molecular imprinting. Finally, we highlight areas where ongoing and future efforts should yield information critical to our understanding of the underlying mechanisms sufficient to permit the rational design of molecularly imprinted polymers.

  • 5.
    Rosengren, Annika M.
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karlsson, Björn C. G.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Spectroscopic evidence for the presence of the cyclic hemiketal form of warfarinin aqueous solution: Consequences for bioavailability2011In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 407, no 2, p. 318-320Article in journal (Refereed)
    Abstract [en]

    Warfarin is an important oral anticoagulant drug that demonstrates a molecular-environment dependent structural diversity. Previous investigations of warfarin’s ensemble of isomers in organic solvent-based environments have pointed to the importance of the closed-ring cyclic hemiketal form of the drug in non-polar environments, e.g. the interior of proteins, enzymes and biomembranes. Detection of the presence of these isomers in polar environments has not yet been reported. Here, we demonstrate the presence of the cyclic hemiketal structural form of warfarin under aqueous conditions. This finding underscores the importance considering all structural isomers of this drug when making predictions on warfarin’s bioavailability.

  • 6.
    Wiklander, Jesper G.
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karlsson, Björn C. G.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Aastrup, Teodor
    Nicholls, Ian A.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Towards a synthetic avidin mimic2011In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 400, no 5, p. 1397-1404Article in journal (Refereed)
    Abstract [en]

    A series of streptavidin-mimicking molecularly imprinted polymers has been developed and evaluated for their biotin binding characteristics. A combination of molecular dynamics and NMR spectroscopy was used to examine potential polymer systems, in particular with the functional monomers methacrylic acid and 2-acrylamidopyridine. The synthesis of copolymers of ethylene dimethacrylate and one or both of these functional monomers was performed. A combination of radioligand binding studies and surface area analyses demonstrated the presence of selectivity in polymers prepared using methacrylic acid as the functional monomer. This was predicted by the molecular dynamics studies showing the power of this methodology as a prognostic tool for predicting the behavior of molecularly imprinted polymers.

  • 7.
    Karlsson, Björn C. G.
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rosengren, Annika M.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Näslund, Inga
    FOI.
    Andersson, Per Ola
    FOI.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Synthetic Human Serum Albumin Sudlow I Binding Site Mimics2010In: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 53, no 22, p. 7932-7937Article in journal (Refereed)
    Abstract [en]

    Here, we report the design, synthesis, and characterization of molecularly imprinted polymer (MIP) derived mimics of the human serum albumin (HSA) Sudlow I site-the binding site for the anticoagulant warfarin. MIP design was based upon a combination of experimental (H-1 NMR) and computational (molecular dynamics) methods, Two MIPs and corresponding nonimprinted reference polymers were synthesized and characterized (scanning electron microscopy; nitrogen sorption; and Fourier transform infrared spectroscopy). MIP-ligand recognition was examined using radioligand binding studies, where the largest number of selective sites was found in a warfarin-imprinted methacrylic acid ethylene dimethacrylate copolymer (MAA-MIP). The warfarin selectivity of this MIP was confirmed using radioligand displacement and zonal chromatographic studies. A direct comparison of MIP-warfarin binding characteristics with those of the HSA Sudlow I binding site was made, and similarities in site population (per gram polymer or protein) and affinities were observed. The warfarin selectivity of the MIP suggests its potential for use as a recognition element in a MIP-based warfarin sensor and even as a model to aid in understanding and steering blood-plasma protein-regulated transport processes or even for the development of warfarin sensors.

  • 8.
    Henschel, Henning
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karlsson, Björn C. G.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rosengren, Annika M.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    The Mechanistic Basis for Warfarin’s Structural Diversity and Implications for Its Bioavailability2010In: Journal of Molecular Structure: THEOCHEM, ISSN 0166-1280, Vol. 958, p. 7-9Article in journal (Refereed)
    Abstract [en]

    The anticoagulent drug warfarin exhibits chameleon-like isomerism, where the environment-dependent composition of the ensemble of structures greatly influences its bioavailability. Here, the mechanism of conversion between the major isomeric forms is studied. The dramatic differences in transition state energies, as determined by density functional calculations, highlight the necessity for the involvement of intermolecular interactions in the key proton transfer step. A viable model for the mechanism underlying the isomerization reactions is presented.

  • 9.
    Nicholls, Ian A.
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karlsson, Björn C. G.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rosengren, Annika M.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Henschel, Henning
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Warfarin: an environment-dependent switchable molecular probe2010In: Journal of Molecular Recognition, ISSN 0952-3499, E-ISSN 1099-1352, Vol. 23, no 6, p. 604-608Article in journal (Refereed)
    Abstract [en]

    The complex nature of the structure of the anticoagulant warfarin is reflected in the diversity of binding modes observed in warfarin–protein recognition systems. A series of theoretical, 1H-NMR and steady state and time resolved fluorescence spectroscopic studies, have been used to establish correlations between the molecular environment provided by various solvent systems and the relative concentrations of the various members of warfarin's ensemble of isomers. A consequence of these observations is that the judicious choice of solvent system or molecular environment of warfarin allows for manipulation of the position of the equilibrium between isomeric structures such as the hemiacetal and open phenol-keto forms, the latter even possible in a deprotonated form, where in each case unique spectroscopic properties are exhibited by the respective structures. Collectively, warfarin's capacity to adapt its structure as a function of environment in conjunction with the fluorescence behaviours of the various isomers together provide an environment-dependent molecular switch with reporter properties, which allows for the simultaneous detection of warfarin in different states with lifetimes spanning the range < 0.10–5.5 ns. These characteristics are here used to examine warfarin binding domains in a series of materials (solvents, protein, inorganic matrix and synthetic polymer). Moreover, these studies demonstrate the potential for using warfarin, or other switchable analogues thereof, as a tool for studying molecular level characteristics, for example local dielectricity. Copyright © 2010 John Wiley & Sons, Ltd.

  • 10.
    Karlsson, Björn C. G.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Rosengren, Annika M.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Andersson, Per-Ola
    FOI CBRN Defence and Security, Umeå.
    Nicholls, Ian A.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Molecular Insights on the Two Fluorescence Lifetimes Displayed by Warfarin from Fluorescence Anisotropy and Molecular Dynamics Studies2009In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 113, no 22, p. 7945-7949Article in journal (Refereed)
    Abstract [en]

    A series of steady-state fluorescence anisotropy experiments has been performed to demonstrate the presence of a deprotonated open side chain form of warfarin in organic environments. We explain the observed emission-wavelength-dependent anisotropy of warfarin in ethanol, 2-propanol, and acetonitrile due to the coexistence of neutral isomers and deprotonated open side chain forms displaying different fluorescence decay kinetics. To investigate solvent-solute interactions in more detail, a series of molecular dynamics simulations was performed to study warfarin solvation and to predict the time scale of rotational diffusion displayed by this compound. Predictions obtained provide an explanation for the nonzero values in anisotropy observed for neutral isomers of warfarin associated with the short fluorescence lifetime (tau < 0.1 ns) and for an approximately zero anisotropy observed for the deprotonated open side chain form, which is associated with the longer fluorescence lifetime (tau = 0.5-1.6 ns). Finally, we address the potential use of fluorescence anisotropy for an increased understanding of the structural diversity of warfarin in protein binding pockets.

  • 11.
    Karlsson, Björn C. G.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    O'Mahony, John
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Karlsson, Jesper G.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Bengtsson, Helen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Eriksson, Leif A
    Nicholls, Ian A.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Structure and Dynamics of Monomer-Template Complexation: An Explanation for Molecularly Imprinted Polymer Recognition Site Heterogeneity2009In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 37, p. 13297-13304Article in journal (Refereed)
    Abstract [en]

    We here present the first simulation of a complete molecularly imprinted polymer prepolymerization system. Molecular dynamics studies were performed for a system comprising a total of 1199 discrete molecules, replicating the components and concentrations employed in the corresponding polymer synthesis. The observed interactions correlate well with results obtained from (1)H NMR spectroscopic studies. Comparison with simulations performed in the absence of cross-linking agent (ethylene dimethacrylate) demonstrated its significance in the formation of ligand recognition sites. Moreover, the influence of events such as template-template (bupivacaine) and monomer-monomer (methacrylic acid) self-association, porogen-template interactions, and template conformational variability was revealed. The template recognition capacity of the modeled polymer system was verified by synthesis of imprinted and reference polymers and subsequent radioligand binding Analysis. Collectively, through a series of statistical analyses of molecular trajectories in conjunction with spectroscopic data it was demonstrated that an ensemble of complex structures is present in the prepolymerization mixture and that this diversity is the basis for the binding site heterogeneity observed in molecularly imprinted polymers (MIPs) prepared using the noncovalent strategy.

  • 12.
    Nicholls, Ian A.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Andersson, Håkan S.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Charlton, Christy
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Henschel, Henning
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Karlsson, Björn C. G.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Karlsson, Jesper G.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    O'Mahony, John
    Rosengren, Annika M.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Rosengren, K. Johan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Wikman, Susanne
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Theoretical and Computational Strategies for Rational Molecularly Imprinted Polymer Design2009In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 25, no 3, p. 543-552Article in journal (Refereed)
    Abstract [en]

    The further evolution of molecularly imprinted polymer science and technology necessitates the development of robust predictive tools capable of handling the complexity of molecular imprinting systems. A combination of the rapid growth in computer power over the past decade and significant software developments have opened new possibilities for simulating aspects of the complex molecular imprinting process. We present here a survey of the current status of the use of in silico-based approaches to aspects of molecular imprinting. Finally, we highlight areas where ongoing and future efforts should yield information critical to our understanding of the underlying mechanisms sufficient to permit the rational design of molecularly imprinted polymers. 

  • 13. O'Mahony, John
    et al.
    Karlsson, Björn C. G.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Mizaikoff, B
    Nicholls, Ian A.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Correlated theoretical, spectroscopic and X-ray crystallographic studies of a non-covalent molecularly imprinted polymerisation system2007In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 132, p. 1161-1168Article in journal (Refereed)
  • 14.
    Karlsson, Björn C. G.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Rosengren, Annika M.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Andersson, Per-Ola
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Nicholls, Ian A.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    The Spectrophysics of Warfarin: Implications for Protein Binding2007In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 111, p. 10520-10528Article in journal (Refereed)
  • 15.
    Karlsson, Jesper G
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Karlsson, Björn C. G.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Andersson, L I
    Nicholls, Ian A.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    The roles of template complexation and ligand binding conditions on recognition in bupivacaine molecularly imprinted polymers2004In: Analyst, Vol. 129, no 5, p. 456-462Article in journal (Refereed)
1 - 15 of 15
CiteExportLink to result list
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  • ieee
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  • en-GB
  • en-US
  • fi-FI
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  • text
  • asciidoc
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