Authors: T. Schreiber, K. Niedergall, D. Wojciukiewicz, T. Gose, C. Gruber-Traub, A. Weber, T. Hirth, G.E.M. Tovar
Affilation: University of Stuttgart & Fraunhofer Gesellschaft, Germany
Pages: 242 - 245
Keywords: molecular imprinting, miniemulsion polymerisation, molecular recognition, peptide imprinting, interfacial imprinting
Communication of living systems is done by molecular recognition. This central principle of the living world is performed at the contact sites of different objects such as single macromolecules or highly complex supramolecular assemblies as which living cells may be described. Molecular recognition capabilities are evoked at artificial materials by the NANOCYTES-technology of the Fraunhofer IGB. The biomimetic nanoparticles described here, possess such molecularly recognizing properties. For this purpose they carry molecularly defined binding sites at their surface. These binding sites are either composed from biologically derived macromolecules or fully synthetic receptors. Core-shell nanoparticles are particularly suited for this purpose, e.g. to immobilise a specific protein or a protein complex at their shell surface. Entirely synthetic molecularly recognising nanoparticles can also be prepared by chemical nanotechnology. A cooperative chemical reaction evokes the formation of specific molecular binding sites at the surface of copolymer nanoparticles. Such synthetic receptors may be employed e.g. as specific absorbers to remove micropollutants from the drinking water cycle or as functional unit of a biosensor. The talk will highlight the design and application of biomimetic nanoparticles based on the structural concepts described above. Especially molecular imprinting of polymers(MIP) is a highly attractive route to synthesize artificial receptors which combine the specificity of biological binding sites with the superior chemical stability of synthetic materials , Selective molecular binding sites are induced in a growing crosslinked polymeric material by template interaction of a nonpolymerising agent which interact noncovalently with specific parts in the polymer. The templates are washed from the generated polymer monoliths and the induced artificial binding sites can be applied for molecular recognition reactions. Nanostructured MIP monoliths (nanoMIP) can be prepared by a modified miniemulsion polymerisation technique, where the monomer, the template, the cross-linker, and the initiator are reacted in the droplet cavities of an emulsion [2,3]. The reaction, although complex, runs in a single reaction chamber and in a single-step chemical process. Thus a variety of active agents ranging from low molecular weight drugs to peptides, proteins and biomacromolecules can be imprinted [4,5] NanoMIP dispose of the high surface area of nanostructrued material and are thus highly attractive for use as specifically absorbing material. Moreover, nanoMIP synthesis overcomes some crucial limitations of the preparation of imprinted material such as chemical inhomogeneity of a molecular imprinted polymeric matrix. The technique of miniemulsion polymerization results in particles with typical sizes between 50 and 300 nm. Besides classic miniemulsion polymerization (hydrophobic phase emulsified in hydrophilic phase – here water), a MIP technique also based on inverse miniemulsion polymerization is established. Thus, possible templates can be chosen from the full range of hydrophilic over amphiphilic to hydrophobic molecules.5 Additives like inorganic nanocrystals or organic fluorophores can be easily added to polymerization process. Thus nanostructrured hybrid-materials with multiple properties (fluorescence, magnetism) and specific binding sites are easily designed as valuable material in modern bio-analytics and diagnostics as well as in down stream processing in chemical and pharmaceutical industry. Widespread use in applications ranging from medical technology to environmental technology can be envisaged with the approach and will be discussed. 1 C. Alexander, H. S. Andersson, L. I. Andersson, R. J. Ansell, N. Kirsch, I. A. Nicholls, J. O‘Mahony, M. J. Whitcombe, Molecular imprinting science and technology: a survey of the literature for the years up to and including 2003., Journal of Molecular Recognition 2006, 19, 106-180. 2 D. Vaihinger, K. Landfester, I. Kräuter, H. Brunner, G. E. M. Tovar, Molecularly imprinted polymer nanospheres as synthetic affinity receptors obtained by miniemulsion polymerisation., Macromolecular Chemistry and Physics, 2002, 203, 1965-1973. 3 G. E. M. Tovar, I. Kräuter, C. Gruber: Molecularly Imprinted Polymer Nanospheres as Fully Synthetic Affinity Receptors., Top. Curr. Chem. 2003, 227, 125-144. 4 A. Weber, M. Dettling, I. Kräuter, H. Brunner, G. E. M. Tovar: Isothermal titration calorimetry of molecularly imprinted polymer nanospheres., Macromol. Rapid. Commun. 2002, 23, 824-828. 5 M. Herold, G.E.M. Tovar, C. Gruber, M. Dettling, S. Sezgin, H. Brunner, Molecular recognition by imprinted polymer nanospheres – fundamental research and application., Polym. Prepr., 2005, 46, 1125-1126.